Mounting a Pentax 42mm screw mount lens or a Nikon F lens on a Canon T90

Mirrorless cameras have made us familiar with the concept of mounting old manual focus lenses manufactured many decades ago on a modern camera. A little known fact is that Canon’s T90 (their top of the line manual focus SLR in the eighties) can work in a full featured semi-automatic mode with Pentax screw mount AND Nikon F lenses, thanks to adapters which were at some point sold by Canon themselves.

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Canon T90 with Asahi Pentax Super Takumar (35mm f/2)

How is it even possible?

The Canon FD mount has one of the shortest flange to film distances of all 35mm SLRs at 42mm. On the other hand, the Nikon F flange distance is one of the longest, at 46.5mm (source:  Wikipedia – Flange focal distance). The “universal” 42mm screw mount (used by Asahi Pentax and the East German offspring of Zeiss until the mid seventies) is close to the Nikon’s flange distance at 45.6mm. Therefore, if a lens mount adapter can be made less than 4.5 mm thick, it will be possible to mount a Nikon lens on a Canon camera without losing the ability to focus to the infinite (and 3.6mm is the right thickness for a 42mm screw mount adapter).

The difficult part of course is to transmit aperture information to and from the lens – but if the camera is designed to work – at least in one specific mode –  without having to exchange information with the lens (semi-automatic exposure with stopped down metering and no aperture pre-selection, for instance), a very simple lens mount converter will be able to do the job.

Such adapters can be found on eBay for less than $10.00 (recent Chinese manufacturing). More surprisingly, it appears that Canon used to sell Canon branded, made in Japan adapters in the sixties (source: Cameraquest, Pacificrim).

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Canon Lens Mount Converters – from Canon’s 1969 System Equipment catalog (courtesy: Pacificrim.com)

42mm screw mount lenses

I recently found one of those 42mm screw mount to FD adapters, (it does not look like the genuine Canon item shown in the picture below, but it’s made in Japan) and decided to test it with a Pentax Super Takumar 35mm F/2 on a Canon T90.

The T90 is an interesting camera – while it does not offer a true semi-automatic metering mode at full aperture with Canon’s native FD lenses, it simply has to be set to stopped down metering to gain a fully functional semi-automatic exposure mode, non only with Canon FD and FL lenses, but also with “adapted” screw mount lenses.

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Canon Lens Mounter Converter P (Credit: origin of photography unknown)

 

The main mission of a lens mount adapter is to position the guest lens (the Pentax 35 mm f/2 in our case) so that its flange will sit at precisely 45.6mm from the film plane – as if it was mounted on an Asahi Pentax camera.

The converter does not provides any mechanical linkage between the adapted lens and the camera, and it has no mechanism to force the lens to stop down to the pre-selected aperture when the photographer presses the shutter release. Therefore, it can only work with lenses with no automatic aperture pre-selection, or lenses where the aperture pre-selection can be switched off to force the lens to always keep the iris at the value shown on the aperture ring.

Not all 42mm screw mount lenses are created equal

Lenses deprived of such a switch can only be operated at their maximum aperture – which makes them mostly unusable. Lenses (such as the Fujinon screw mount lenses) designed to support full aperture metering add another constraint – they typically use a non-standard derivative of the 42mm lens mount (with a protruding pin in the case of the Fujinon) and can not be physically mounted on this adapter (I tried).

Nikon lenses

Nikon has been using the same F bayonet layout for 60 years, but had to go through many iterations of its lens mount to stay current (support of through the lens metering (TTL), introduction of program modes, of matrix metering, and many variants of autofocus).

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Pixco Nikon AI to FD adapter (bought on eBay)

Genuine and Canon-branded Nikon AI to FD adapters are rare and very expensive (I saw one selling for $150.00 on eBay under the name “MC-N Lens Mount Converter”). I bought  a Chinese one, for a fraction of the cost.

Being devoid of any aperture transmission mechanism, the converter is compatible with any Nikon lens AI, AIS, AF, AF-D lens, and I don’t see why it could not also accept pre-AI lenses.

Does it work? 

Yes. With the right adapter, a 42mm Screw Mount lens set in “manual” (no aperture pre-selection) will work on the T90 the same way a Canon FL lens (set in “manual”) would.

  • screw the adapter on the lens
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The screw mount to FD adapter.
  • Mount the lens on the Canon T90
  • Set the lens to “M”
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Asahi Pentax Super Takumar lens – it has to be set to “manual”
  • push the stopped down metering lever
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The stopped down metering / depth of field preview lever has to be pushed towards the lens.
  • turn the camera ON
  • set the Exposure Mode to “T” (for shutter priority exposure)
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Canon T90 – the settings for shooting stopped down in semi-auto exposure mode
  • turn the aperture ring or the control wheel (controlling the shutter speed) to adjust the exposure as if it was a Canon FL lens used stopped down (the “OP” message on the viewfinder’s LED panel means “Open the iris”, “CL” stands for “close the iris” and “oo”  for “you nailed it”.
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T90 – semi-auto mode – stopped down. Correct exposure – (cursor and triangle aligned on bar graph, “oo” message)
  • Of course, you operate stopped down – but it’s not so much of an issue:
    • the viewfinder of the T90 is very bright and the matt screen very fine, you can focus accurately up to f/8 if you shoot outside on a sunny day,
    • photographers are unlikely to mount slow lenses on the camera, or to shoot at F/16. They will most probably use the converters to mount old and ultra-luminous lenses on the T90, for the bokeh, and for the way the pictures shot with old lenses look.

With screw mount lenses, the T90 is as easy to use as any other semi auto camera, and exposure seems accurate (I obtained the same recommended aperture with the Pentax lens, the FL and the FD lenses, and on a Nikon camera I used as a benchmark).

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Canon T90 with a Nikon 50mm AF lens. It can be physically mounted but the exposure is off by at least 1 stop (compared to FL or FD lenses)

With Nikon lenses, I observed multiple issues: with some lenses, the aperture ring of the lens does not seem to control the aperture, and with some lenses, the exposure is off (1 to 1 1/2 stop) compared with FD, FL or Pentax screw mount lenses. I suspect it’s because the lever controlling the aperture on a Nikon lens is normally pushed to the preselected aperture by a spring loaded lever on a Nikon camera’s body. With this adapter, the spring loaded lever is missing.

Does it make sense?

Owners of 42 mm screw mount lens with manual preselection don’t have many options if they want to use their lens “natively” on modern cameras: Pentax stopped selling screw mount cameras in 1975, Fujica at the end of the seventies, and Cosina briefly sold a Voigtlander Bessaflex SLR in small volumes at the beginning of this century. Nothing recent or widely available. The best they can do is use adapters, to mount their lens on Pentax K SLRs and dSLRs, or of course on many mirrorless cameras. In that perspective, if you’re a T90 enthusiast and still own a few very good 42mm lenses it could  make sense to look for a 42mm to FD adapter.

I’m less convinced it makes sense for owners of old Nikon lenses to mount them on a T90.  Nikon lenses don’t like to be mounted on an adapter that does not control their aperture lever. And if you have old Nikkor lenses that you love, there is no shortage of good film and digital Nikon cameras which still accept them, and will offer full aperture metering and more auto exposure options than an adapted lens on the T90 .

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Canon FT with Nikkor AI lens – it’s not because it’s possible that you should do it.

Other Canon bodies

Any Canon body which can operate stopped down with Canon FL lenses can in theory work with the 42mm screw mount or the Nikon F adapter.

  • Canon AV-1: being an “aperture priority auto exposure camera,  it works stopped down with Canon FL lenses and adapted screw mount lenses.
  • Canon FT: a semi-automatic camera operating natively with FL lenses, it also works with adapted screw mount lenses.

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Plancy l’Abbaye – France – Canon T90 – Canon FD 24mm lens – Kodak Ektar 100. I was surprised by the way the Ektar film rendered the colors – pretty different from the reality.

 

 

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Canon T90 – After a few rolls of film…

High level, the T90 is a top of the line manual focus and motorized SLR, with a long eye point viewfinder, multiple auto-exposure and metering modes, on the film flash metering, and a very fast (1/4000 sec) shutter. Besides auto-focus, the only major feature missing is matrix metering.

Canon T90 – the ergonomics of an EOS camera with an FD lens mount

Launched in 1986 (one year after the Minolta 7000), the T90 did not stay under the spotlights for a long time. A very innovative camera, it was probably expected to stay at the top of Canon’s line of FD mount SLRs for a decade, but the success of the Minolta 7000 (and the failure of their first auto-focus SLR, the T80) forced Canon to change their plans in a hurry. They decided to abandon the FD mount, and somehow derived their first two successful auto-focus SLRs (the EOS 650 and 620) from the T90. Less than 12 months after its introduction, the T90 had been relegated to a niche – a camera for well heeled enthusiasts and conservative pros refusing to throw away their FD lenses  to upgrade to the new auto-focus product line.

Designed for demanding photographers, the T90 had an impressive specifications sheet, and  very few real competitors in its heyday:

  • Nikon had nothing approaching its capabilities until the Nikon F4 and N8008/F801 were launched in 1988. But both were autofocus cameras with matrix metering, and sold for much more than the T90.
  • the Olympus OM-4Ti had similar capabilities for metering and its flash system was even more elaborate than the T90’s flash, but it was miles behind when it came to shutter performance and its short eye-point viewfinder was rather small for photographers wearing glasses.

Contax and Leica R cameras of the early to mid nineties also had approaching characteristics,  but when they came to the market, most of the photographers already had adopted auto-focus cameras, and the T90 had been retired for some time.

The T90 was also extremely expensive:

At approximately $500.00 body only in 1986, it was priced in the same ballpark as the Olympus OM-4T, which means it was:

  • more expensive than any other 35mm manual focus camera, except for modular professional bodies (Canon’s F-1, Nikon’s F-3 or Pentax’s LX), and of course the Leicas.
  • more expensive than any autofocus SLR camera, including Canon’s own EOS 650 and 620 – until the launch of the Nikon F4 and the EOS-1 at the end of the eighties.

Buying and using a T90 now

You may prefer a smaller, simpler, lighter and quieter manual focus camera, but if you want a long eye point viewfinder, multiple automatic modes, multiple metering options and support of Canon FD lenses, there is not much choice.

  • Probably because of the bad reputation of old electronics cameras, and specifically of potential reliability and maintenance issues (risk of sticky shutter failure, lithium battery soldered on the circuit board), it can be had for relatively little money (less than $100.00 for a very nice one on auction sites)
Canon T90 – the commands used less frequently are at the bottom of the camera’s back, and behind a door at the right of the body.

The user manual is fairly large for a camera of that era (126 pages) but apart from all the metering and exposure compensation options which can be fairly complex, the T90 is very simple to use, and benefits from very good ergonomics:

  • All the major settings are visualized on a single top plate LCD – very clear and very informative
  • The essential settings (exposure, metering) are accessed through two big buttons  and the control wheel.
  • Great viewfinder – very clear and fine focusing screen, just enough information, and for a photographer wearing glasses – like me –  it’s the perfect compromise between a reasonably long eye point and a reasonable enlargement level.

I did not like a few details  – the control wheel is vertical – I’m used to horizontal on Nikon or Fuji bodies –  in some modes, the viewfinder display is only active if the shutter release button is half pressed, and when you lift your finger from the shutter release to turn the control wheel with your index, the viewfinder display turns dark.

Canon T90 – Vivitar 135mm f/2.8 – Jules

Metering

  • Generally speaking, the camera is easy to use, but understanding the finesse of the metering options requires to go back to the user manual – and experiment.
  • The camera offers 3 metering modes, but on the T90 the center weighted average mode I’ve been using on manual focus SLRs since my formative years is not usable except in the most straightforward lighting situations: the “average” metering mode does not support exposure memorization, and the second best option to control exposure in complex situations on other cameras – switching to semi-automatic exposure  – only works with stopped down metering on the T90.

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    T90 – Very informative viewfinder. It combines a LCD bar graph display on the right with a LED display at the bottom. Here the camera is set to semi-auto mode – stopped down. Correct exposure – (cursor and triangle aligned on bar graph, “oo” message)
  •  As a result I kept the camera set to Partial metering  most of the time. Think of Partial as a form of spot, with a very large metering area at the center of the frame.  Partial metering has been available in Canon  SLRs since the early seventies (on the the FTb, for instance) and is still an option on current EOS digital SLRs. On the T90, this mode supports exposure memorization. By the looks of my pictures, it seems to treat equally the lower and the upper portions of the scene, often resulting in a slight under-exposure of the picture if a portion of the sky is included in the metering area.

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    T90 – Viewfinder when the camera is powered off. The “partial” metering zone corresponds to the largest of the circles at the center of the viewfinder.
  • I wanted to test the Spot, Multi-spot, and High Key /Low Key modes.
    The scenes I exposed in Spot ended up being exposed correctly.
    I played with Multi-spot and the Hi key/Lo key corrections, but shot very few pictures in those modes: those options leave the photographer totally in charge, but require time, as well as a serious knowledge of the theory of exposure (the 18% gray charts and all those sorts of things). To make the matter worse, the implementation of High Key/Low Key is not novice friendly: even the OM-4t is simpler: on the Olympus, the Hi and Lo buttons provide a constant level of correction +2 EV and -2 2/3 EV respectively. On the T90, it’s up to the photographer to adjust the correction, by steps of 1/2 EV. It’s more flexible than the Olympus, but the photographer will have to remember to push the HI button 4 times when shooting a white dog sitting on white sofa.
  • The main constraint, of course, is that film offers no immediate feedback. In order to learn how to take advantage of the advanced exposure modes, you  have to perform systematic tests, take notes, and when you finally receive the processed negatives, go through your notes and try understand what you did right and where you went wrong.  Who has the patience for that?
Canon T90 – Canon FD 24mm f/2.8. Kodak Ektar. The beach in the morning – Peñíscola, Spain.

Lenses

  • I tend to shoot a lot with wide angle lenses (24mm, 28mm), but I need longer focal lenses from time to time, and don’t like carrying too many lenses at the same time.
  • Trans-standard zooms are supremely convenient. But in the mid-eighties, very good trans-standard zooms – lenses that could be at the same time sharp, distortion free, compact and reasonably fast (f2.8-4 for instance), simply did not exist. Nikon introduced their first 35-70 f/2.8 AF zoom with the F4 camera, Canon only launched a 28-70mm F/2.8-4L auto-focus zoom in 1988, and neither of them are light or compact.
  • Therefore, the options in the FD mount are limited: no “L” zoom, a few sliding aperture entry level zooms, a huge 35-70 f/2.8-3.5 from the early seventies, and two large and heavy constant aperture zooms, the 35-105 f/3.5 and the 28-85 f/4. I bought the 35-105 f/3.5 a while ago and did not like the pictures it delivered at all (maybe it was a bad copy – on the forums the lens has the reputation of being the best of its class when it’s in top condition).  I’m not inclined to buy the 28-85 f/4, which looks very similar to the 35-105 and is not as highly rated.
  • I will have to explore the world of independent lens makers, or bite the bullet and buy a sliding aperture Canon zoom – the 35-105 f/3.5-4.5 may be better than its reputation.
  • As mentioned above, the T90 does not offer full aperture metering in semi-auto exposure mode. But its semi-auto mode is very well implemented if you accept to work with the lens stopped down. Interestingly, the T90 not only supports older Canon FL lenses, but, with adapters sold by Canon in the sixties and seventies, it also accepts 42mm screw mount lenses,  Exacta, Leica Visoflex and even Nikon F lenses. I could find one of those screw mount adapters recently, and there are a few very luminous Pentax screw mount lenses that I’d like to try on the T90.
Canon T90 – Canon FD 24mm f/2.8 – Ilford FP4 film. Peñíscola, Spain

My conclusions:

I’ve never really been into Canon cameras – and I only started using Canon SLRs recently because I was given a few bodies and lenses. Logically, I should have felt little affinity with the T90: it is pure Canon DNA, combining some characteristics originating in the FTb and AE-1 generations with the ergonomics of modern EOS cameras. But the truth is that I love this camera. It’s one of the most satisfying film cameras to use, with no real equivalent:

  • The Canon A-1:
    • the A-1 is a good camera, but I like the T90 much better (better viewfinder, better shutter, better ergonomics, better build quality, more metering options for the day I want to think hard about the exposure).
  • The Nikon SLRs of the mid eighties
    • Nikon has no equivalent to the T90. The F3 is a heavy, conventional, aperture preferred auto camera, with a viewfinder even larger than the T90, but far less informative; it’s rock solid and will quietly get the job done, but it feels much older than the T90. Another generation.
    • Compared to the T90, the FE2 is a simple, light and compact camera  with a very fast shutter. Like the F3, it only offers aperture priority auto-exposure in conjunction with center weighted average metering, and in most situations, it’s going to be good enough. Its viewfinder is very bright, it offers one of the best implementations of semi-auto exposure I know of, but with its very short eye point, it will force photographers wearing glasses to look left and right to see the entirety of the focusing screen.
  • The Olympus SLRs:
    • Even if it has some characteristics in common with the OM-4 (the multi-spot and hi-key/lo key metering modes or the flash control options), the T90 looks like the polar opposite of the OM-4. The design and the ergonomics of the OM-4 are deeply rooted in the early seventies. On the other hand, the T90 introduced a way of interacting with a camera still followed today by Canon, Nikon or Sony for their top of the line dSLRs.
      I’ve not been convinced of the usefulness of the multi-spot and hi-key/lo-key modes of the T90 – too slow, too complex, not better than operating with spot metering on a good semi-auto camera – and I suspect that my opinion would not be very different if I tested those features on the OM-4. But if you don’t use those metering modes, why bother with an OM-4? An OM-2 or an OM-2 Spot Program will do a similar job, and are simpler and cheaper cameras.

If you consider the camera’s characteristics – its specs sheet – it is very telling that the closest Minolta or Nikon cameras – motorized, with a  long eye point viewfinder, multiple auto-exposure options, multiple metering options including Spot –  came a few years after the T90 (with the Maxxum 8000i or the N8008/F801). But with auto-focus and matrix metering, they clearly belonged to another generation and offered a different user experience.

Despite the apparent similarity of their ergonomics, shooting with the T90 is to a large extent the opposite of shooting with a modern auto-focus/matrix metering  SLR or dSLR. The T90 leaves you in charge of the focus and the exposure. Focusing is not very difficult (the viewfinder is large and bright), but getting the exposure right requires some effort – in particular because Canon decided to limit what the photographer could do with Average metering. The T90 is a camera for perfectionists, who believe that with the right set of tools and some effort, they can get better images than what a modern auto-everything camera would give them.


More about the T90:

Cameraquest: https://cameraquest.com/t90.htm


Canon T90 – Canon FD 24mm f/2.8 – Fujicolor 400. “La Maison aux Bambous”, Vinay, France

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The Canon T90 – first impressions

The Postal Service just delivered a Canon T90 at my door step. I opened the box, inserted batteries, mounted a lens, and swiched it on. The T90 is a disconcerting camera, and I was in for a few surprises.

Why a T90? 

Recently I’ve been looking for a manual focus camera with a larger viewfinder than my Nikon FE2, and a bit more feature rich than the austere Nikon F3. I wanted to play with more metering options (spot, multi-spot, highlight, shadows) than what the FE2 and the F3 have to offer. And at the same time, I did not want to spend money on a new family of lenses, which excluded Contax, Leica, Minolta and Pentax, and limited my choice to Canon, Nikon and Olympus. I could have splurged on an Olympus OM-4T, but $200.00 is a minimum for a working copy in so-so condition sourced in Japan, and the beautiful ones are many times more expensive. Nikon had no manual focus SLR that interested me (I have used the FA and the FG in the past and did not like them, and the N2000 and N6000 are just mid level autofocus cameras deprived of autofocus).  That left us with Canon, and the T90.

The T90 is a very interesting piece of hardware. It’s at the same time a formidable precursor of all the Canon high-end EOS film and digital cameras to come, a shameless copy of the Olympus OM-4 (metering system, OTF flash), the most elaborate of the Canon manual focus reflex cameras, and an evolutionary dead end. It was launched in February 1986, one year after the Minolta Maxxum 7000, and was only manufactured for a few months, leaving the spotlights in favor of the new EOS autofocus product line, presented in March 1987. It is often seen as a test bed for the ideas successfully implemented in the EOS cameras. It’s a way for Canon to finish a long chapter of its history on a bright note, and for its faithful customers, one last opportunity to spend a lot of money on a high-end camera supporting the FL and FD lenses.

A lot has been written about the T90, its genesis and its legacy. There are countless descriptions and reviews of the T90  on the Internets. I listed a few links at the end of this post. I won’t write the nth review here. Today, I’ll share my first impressions, trying to understand how the camera can fit with the way I take pictures. And later, after my  summer vacation, I’ll come back with more definitive conclusions.

LCD display on the right side of top plate, control wheel, shutter release and spot metering buttons at the top of the grip. The ergonomics of a modern camera.

The first impression: it looks and feels like an EOS camera…

The T90 is a camera full of paradoxes. It looks and feels like a modern EOS camera (polycarbonate body and rubber covered grip, LCD display on the right of the top plate, control wheel), and when you bring the camera to your eye, you see the same very bright and smooth focusing screen that you would see through the same long eye-point viewfinder in a more recent autofocus SLR. But press the shutter release lightly, and …

  1. The image in the viewfinder stays blurry. Of course, it’s a manual focus camera…But intuitively, for a fraction of a second, because the camera looks and feels like an EOS, I had expected it would find the focus for me (*)
  2. You press the shutter. It’s LOUD. Really LOUD. More than a non-motorized film SLR of the previous generation, more than a modern dSLR, and of course, much much more than a mirrorless camera. In all fairness, it should be compared to the few motorized SLRs of the same period capable of shooting  4 frames/ second. I remember the racket when I was shooting with a motorized Nikon FA. It was screaming much louder than the T90.(**)
  3. And it’s heavy. Almost 900g with the batteries. You don’t expect that much weight from a camera with a plastic body.

It’s also very large (in the modern dSLR world only the EOS-1d and the Nikon D5 are larger), but because the FD lenses are much smaller than the huge f/2.8 autofocus zooms that the pros mount in their EOS-1d and D5 today, it does not look as big and intimidating.

…but it’s not an EOS-like camera

It’s a manual focus camera. With no matrix metering. In that sense, it’s a camera of the past, already outdated when it was launched. Like the Olympus OM-4, it’s an attempt to put the photographer at the center of the exposure determination process, when the market was rapidly going in the opposite direction and adopting “evaluative multizone” and “matrix” metering.

The default metering mode – center-weighted average – does not permit you to lock the exposure, and unless you’re willing to operate in full manual exposure mode, you need to switch to the  “partial” (large spot) or “spot” (the really tiny spot at the center of the viewfinder) modes as soon as you want to gain a modicum of control over the exposure of your image.

The “partial” setting lets you lock the exposure values as long as the shutter release button is half pressed, and the elaborate multi-spot, highlight/shadow and exposure memorization functions are only paired with “spot” metering. It should give you enough control over the exposure without ever having to switch to the manual exposure mode.

The manual and semi auto modes are weird, but stopped down aperture is surprisingly useful

The other reason to use the T90 in auto exposure mode is that the manual mode is weird. It’s really a manual mode (not semi-automatic), unless you operate with stopped down metering.

  • If you operate the camera at  full aperture (with a Canon FD lens unlocked from the “A” position), the LED display in the viewfinder only shows the recommended aperture value. But it does not give you any indication about the current aperture value, and there is no + or – sign in the viewfinder to tell you whether your image is currently over exposed, under exposed, or just right. The meter of the camera operates as a hand held light meter would, and it looks as if the meter is not coupled to the shutter and aperture commands of the camera. It may work in a studio, but it’s far too slow in the street.
  • However, if you press the “stopped down” lever at the left of the T90, a full featured semi-automatic mode becomes available. Which is fine if you shoot with FL or FD lenses at a wide aperture, but unusable at F/11 and beyond – the viewfinder becomes too dark. It’s frustrating to have to operate FD lenses stopped down, but using FL lenses is surprisingly pleasant. One last gift of Canon to its faithful customers.

Not everything is perfect though: the manual and stopped down modes come with all sorts of limitations, and the camera displays weird error messages if the aperture ring and the depth of field lever are not set as the camera would expect. I don’t know if the limitations are related to programming of the CPU of the camera, or whether they are flaws inherent to the FD mount, or a combination of both. Obviously the all-electric EF mount of the EOS series is a more flexible design.(***)

Canon T90 with a Canon FD 50mm f/3.5 macro lens. Thirty years later an EOS 1d does not look that different.

The Canon FL and FD lenses: they used to be cheap…

When Canon launched the EOS system in 1987, the FL and FD lenses – which are absolutely non-compatible with the EOS cameras, immediately lost most of their resale value. After the T90, Canon only launched one camera using FD lenses: the T60, in 1990. But it’s a rebadged Cosina semi-auto camera (a precursor of the Olympus OM-2000), not a true Canon. So for a very long time, FL and FD lenses – that could only be used on cameras last manufactured in the mid eighties – remained in the “orphan equipment” category, and were cheap, much cheaper than manual focus Nikon lenses, that could (and still can) be used on many current Nikon dSLRs.

The rise of mirrorless system cameras (Olympus, Panasonic, Sony and Fuji), and in particular of the full frame A7 series from Sony has given a new lease of life to manual focus lenses, and to Canon FL and FD lenses in particular. As a result, fast (wide aperture) Canon FL and FD pro and high end lenses have become seriously expensive (as usual, sliding aperture trans-standard zooms remain on the cheap side).

Canon used to propose a very large selection of FD lenses, with different maximal aperture and different qualities of glass in each category (from the ultra-wide angle to the super-tele), but they seem to have neglected the trans-standard zoom segment:  they never offered a constant wide aperture or pro-quality “L” lenses in that focal range, and  the T90 was never bundled with a zoom, but simply with the conventional 50mm f/1.4 prime lens.

Interestingly, the T90 is a good bearer of FL lenses (the semi-automatic exposure mode only works with the lens stopped down, there is no benefit  using FD lenses if you only want to shoot in this mode), and thanks to an adapter (and to the short flange distance of the FL/FD family), it also supports 42mm screw mount lenses.

More to come in a few weeks…


(*): and it happened repeatedly this week. I never had experienced such a thing before (my Nikon FE2 also has a very bright focusing screen, and I often use it with Nikon autofocus lenses, but I never found myself waiting for the camera to focus on its own).

(**): it’s not as loud when operated in stopped down mode. The iris command mechanism is probably the loudest sub system in the camera.

(***): there has been a lot of speculation on why Canon decided to ditch the FD lens mount in favor of a totally new EF mount in 1987. Some  say that the FD mount was too expensive to manufacture, that it was too small and could not be made solidly enough out of plastic, some say it was too small (diameter) and did not leave enough room for the electrical contacts needed for future evolutions, some say it was too small and made the design of ultra-luminous (or ultra-wide angle) lenses too difficult. Some say that the aperture control mechanism of the FD mount was too kludgy and made basic features offered by competitors, such as depth of field preview and semi-automatic exposure too difficult to implement on multi-automatic cameras such as the A-1 or the T90.


Links:

User reviews of Canon bodies and lenses: Canon Classics http://www.canonclassics.com

An interesting take on the design of the T90: http://www.massmadesoul.com/canont90 (and good links too)

The Canon T90 Performance Book. It was sold for $9.99 by Canon dealers: http://satnam.ca/cameras/Canon%20t90_performance_book.pdf

Easy to read reviews of the T-90 and other T-series cameras by Lewis Collard: http://lewiscollard.com/cameras/canon-t90/

In depth description of Canon’s R, FL and FD lens mounts: http://tinkeringwithcameras.blogspot.com/2008/03/canon-lens-mounts-from-r-to-fdn.html

And as usual, MIR’s exhaustive analysis: http://www.mir.com.my/rb/photography/hardwares/classics/canont90/index.htm


Canon T90 on a tripod and black dog.

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Scanning 35mm film – is high-res scanning worth its cost?

Most photo labs propose scans in 3 resolutions: 1000×1500, 2000×3000, 4500×6700. The scans  are saved as jPEGs, with some labs also offering to save 4500 x6700 scans as TIFF files.

In theory, those resolutions correspond to an image of 1.5 Million points (1.5 MP), 6 MP, and 30  MP respectively. In general,

  • 1000x 1500 scans – when available – are virtually free (they’re included in the processing costs by some labs such as thedarkroom.com )
  • 2000 x 3000 scans cost roughly $5 for a full roll (in addition to the processing costs), or .50 per individual image scanned
  • 4400 x 6700 scans cost roughly $11 to $12 per full roll (in addition to the processing costs), or 3.00 per individual scan
  • 4400 x 6700 (TIFF) are the most expensive at $21 per full roll (oldschoolphotolab.com)

Storage constitutes an indirect cost – which doesn’t hurt until you run out of disk space, and have to upgrade your PC, your home NAS  or you online backup plan. But if storing 36 images at 1.5 Mbytes will not break your storage budget, 36 high res TIFF images represent almost 3 Gbytes. The exact size of a JPEG file is difficult to predict (JPEG is a lossy compression format), but in general, the file size of each type of scan falls within those brackets:

  • 1000x 1500 – JPEG -1.5 to 2 Mbytes
  • 2000 x 3000 – JPEG – 3 to 4 Mbytes
  • 4492 x 6776 -JPEG – 12 to 16 Mbytes
  • 4492 x 6776 (TIFF) – 80 MBytes / image

Scan_2000x3000_Piedmont
Atlanta Piedmont Park – Shot with Canon A-1 – Canon FD 35-105 f/3.5 – Fujicolor 400. Scanned at a resolution of  2000 x 3000 – the pictures of this roll are not really better than when scanned at 1000 x 1500 – probably a limitation of the lens (a 35-105 zoom of the seventies)
The tests

I wanted to have a few pictures I had taken a long time ago scanned, and I asked the lab to scan some images in 2000 x 3000, and some in 4400 x 6700. The pictures had been taken with a Minolta 7xi and the famous Angenieux 28-70 f/2.6-2.8 zoom, on Fuji Reala film (the 100 ISO “professional” color film Fujifilm were selling at that time). The pictures had originally been enlarged on photographic paper, and I expected the scans to be good.

I also had a series of images taken recently with a zoom from the early seventies, that had been scanned by the lab at 1000 x1500, that I asked the lab to rescan at 2000 x 3000.

Once the jPEGs were ready, I downloaded them in iPhone and iPad photo galleries, in Photoshop and Lightroom on a laptop, and on WordPress, in order to compare the perceived quality. A reminder of the resolution of a few devices compared to print.

  • iPhone 5 S Retina photo gallery : 1136x 640 (720,000 points) at 326ppi
  • 9.7 in iPad Retina Photo gallery:  2048 x 1536 (3,000,000 points)  at 266 ppi
  • Print 8 x 10: 2400 x 3000 points or 7.2 million points at 300ppi
  • the pictures of this blog are generally saved for the “Large” format proposed by WordPress, at 1024 x 680, corresponding to 600,000 points.

Paris – The Seine – scanned at 2000 x 3000. Minolta 7xi – Angenieux Zoom 28-70 – Fuji Reala film (1992). No visible difference in quality with the 4492 x 6700 scan (look at the details of the Eiffel tower compared to the glass house of the Grand Palais in the image below)
Conclusion

  • Scan at 1000×1500 or 2000×3000 ?
    • on an iPhone, on a 4×6 print, or in a blog supporting 1024 x 680 images (such as this one), there is no visible difference between 1500 x 1000 and 3000 x 2000 scans.
    • For all larger screen or print formats (9.7′ iPad Retina, laptop, 8×11 print, blogs offering to view images at native resolution)  the difference between a scan at 1.5 Million points and a scan at 7 Million points is very visible, unless the original is very poor (low lens resolution, very grainy film, subject slightly out of focus, operator shake at slow shutter speeds). It’s even more visible if you crop the image, even slightly.
  • Scan at 2000×3000 or 4400×6700 ?
    • on an iPhone, iPad 9.7′ Retina or on a 8×11 print – the difference is not really visible.
    • Above that (13 x 20 prints, for instance), the theoretical difference in resolution does not  necessarily translate into a difference in print quality: a 13 x 20 print  represents 24 million points at 300 ppi and the 6 million of points of a 2000×3000 scan should theoretically be overwhelmed, but practically the resolution of the film and of the lens play their part, as the technical limitations of the photographer (focus, shake) do. Large prints are often framed and hung on a wall, and you don’t look at a picture on a wall the same way you look at a 8 x 10 print you hold in your hand. And all technical considerations taken apart, with some subjects, images scanned at 2000×3000 may look as good as images taken at 4492×6770 – it depends on the contrast and quantity of fine details in the subject.

Scanning at 2000×3000 is a good compromise for 35mm film, and my choice when I have film processed. It works fine with any support I use day to day (iDevice, laptop, 8 x 11 prints), is not too expensive and generally produces a visible difference with the 1000×1500 scans.

If I wanted to print a really great picture, an image compelling from an artistic point of view and almost perfect technically (fine grain film, sharp lens, subject in focus, no shake), I would have it scanned at the 4492 x6776 resolution, and saved as TIFF. It would give me no guarantee that the print would be great (there are so many variables), but it would give me the best chances of success.


Scan_4492x6770_Paris-22
Paris – Scan 4492 x 6770 – Shot from the Pont Neuf -Minolta 7xi – Angenieux zoom 28-70 F/2.6 – Fuji Reala (July 1992)

Canon A-1 or Fujica AX-5?

cameras-2-19

Launched in 1978, the  A-1 – the top of Canon’s  A line of cameras, (also composed of the AE-1, AE-1 Program, AV-1, AT-1 and AL-1), was the first single lens reflex camera to offer  three auto exposure modes (Shutter Priority, Aperture Priority and Program) in addition to the Manual mode. The A-1 accepts all Canon FD lenses and (stopped down) can also work with older FL  lenses. A feature loaded and intimidating camera with a very “muscular” design,  it was in fact well thought and easy to use. It sold in the millions.

The AX-5 was the top of Fujica’s new line of bayonet mount 35mm film cameras, launched in 1979 to replace the ST605, ST705 and AZ-1 screw mount cameras. Coming one year after the Canon A-1, the AX-5 offers almost the same feature set, but in a smaller and much more restrained package.

cameragx--5898
Fujica AX-5 (with Tamron 28mm f/2.5 lens).

The AX-5 accepted all Fujica’s newly launched “X-Fujinon” bayonet lenses but could only access the Shutter Priority and Program auto exposure modes when paired with  X-Fujinon “DM” lenses (which have the “A” position on the aperture ring). Lesser camera models (the AX-3 and the STX-1) were usually bundled with “FM” lenses, deprived of the “A” setting.

Back then: how did the two cameras compare?

  • cost and availability
    • the  “A” line of SLRs from Canon was a best seller (probably more than 10 million units were sold), the A-1 representing approximately 1/4th of the total volume. The cameras were widely distributed and competition between retailers played its role: the prices were very similar from one store to the other one, and moderate when compared to the AX-5.
    • Fuji’s retailer network was narrower than  Canon’s, and the AX-5 was the least successful model of Fujica’s “X” line. Retailers did not seem particularly interested in stocking or promoting it, and as a result it was significantly more expensive than the Canon A-1.
Canon A-1 vs Fujica AX-5 – the Canon is bulky and looks “professional”. The Fujica’s design is a bit toned down.
  •  size, weight, features and ergonomics
    • The AX-5 was available with a black or a silver finish, and is smaller and lighter than the A-1. It looks almost “feminine” next to the black-only and larger A-1, with its removable hand grip and its multitude of switches and levers.
    • The feature set of the two cameras is largely identical, with the Fujica only missing access to low shutter speeds (slowest is 2 sec, as opposed to 30 sec for A-1)
    • But the Fujica has far fewer switches and buttons and seems simpler to use. The implementation of the Fujica’s shutter speed and auto mode selection is inspired by the Canon’s, but marginally different:
      • in both cameras, the shutter speed knob has been replaced with a control wheel and the selected shutter speed is shown on a disk, visible through a small window on the top plate.
      • With the A-1, the aperture ring of the lens has to be set on the “A” position to operate in any of the automatic exposure modes (Shutter Priority, Aperture Priority and Program). There is a toggle switch on the front plate of the camera to chose between the Aperture Priority or the Shutter Priority and Program modes. When the photographer switches to Aperture Priority, the desired aperture is selected by rotating the control wheel, and displayed through the same small window on the top plate.
      • To operate in Aperture Priority mode with the AX-5, one has to set the aperture ring of the lens on the desired value, and select the Auto Exposure position with the control wheel. To operate with Shutter Priority or Program modes, one has to set the lens on the  “A” position, select the shutter speed (Shutter Priority) or a full Auto Exposure mode (understand Program) with the control wheel. .
    • On the AX-5, there are two positions on the control wheel for the Auto Exposure command: AE – the camera adjusts the exposure until to the last second, and AEL (auto-exposure lock): the camera will keep the exposure setting determined by the photographer as long as the shutter release button stays half pressed. Very convenient. The Canon A-1 has an exposure lock button on the left of the lens mount to the same effect.
    • The commands of the AX-5 don’t feel as solid as the Canon’s (and the Fujica’s control wheel is too small and protected by a tiny push button lock – not  pleasant to use).
a battle scared Canon A-1 in program mode (lens aperture ring on “A”, mode selector on “Tv”, control wheel on “P”
  • Viewfinder
    • Canon: numeric LEDs – easy to read even in the dark
    • Fujica – strange barrel distortion when wearing glasses – noticeable but not really penalizing when shooting pictures. speed and aperture scales and LEDs intertwined on the left of viewfinder – legible but a bit confusing at the beginning.
viewfinder
Canon A-1 – viewfinder (source MIR)
Fujica viewfinder (source: the Fujica brochure – 1979)
  • Shutter and metering system
    • horizontal cloth – comparable – 1/1000 sec synchro at 1/60e. A-1 goes to 30sec, Fujica up to 2sec only.
  • Lens selection:
    • Canon – uses Canon FD lenses (or FL stopped down). Canon’s catalog of FD lenses was very wide and had something for all types of photographers – from amateurs looking for zooms, up to pros looking for the lens that will make “the” picture that will differentiate them from their competitors. Naturally, compatible lenses of all levels of quality were also available.
    • Fujica X – Fuji’s catalog of lenses included 20 different models, primarily primes lenses from 17mm to 400 mm, and three zooms. The AX-5 could also use screw mount “universal” lenses with an adapter; most of the big vendors of third party lenses (Tamron, Makinon, Soligor, TOU, Komine…) manufactured lenses for the “X” mount, but if the scarcity of lenses today is any indication, anything other than the standard 50mm and the 135mm tele-objective sold in extremely low volumes.
cameragx--5900
Fujica AX-5 – here in Program mode (AE set on the aperture ring of the lens, AE set on the shutter speed control wheel). Note the little shiny button on the left of the control wheel. It has to be pressed to leave the automatic modes.)

Now

  • reliability
    • Canon: built more solidly than the rest of the “A” series, – not only on the outside, but also inside (people who have opened both can testify that the A-1 contains more metallic components than its lesser brothers). The textile shutter may require some TLC (the cameras are almost 40 years old now)
    • Fujica : reliability was questionable back then, with an electro-mecanic shutter release that did not age well at all  (capacitor issues after a few years). Today, unless you’re only looking for a paper weight, only buy a camera tested by the seller, with fresh batteries. The batteries are of a very common type, and “not having a battery to test” is not a valid excuse.
  •  scarcity
    • Canon A-1 – relatively easy to find – they were produced in huge numbers and have been reliable – there are still plenty of them waiting for you.
    • Fujica AX-5 – difficult to find in good condition, in particular in the US. More abundant in Germany and central Europe, sometimes under a retailer’s label such as Porst (the AX-5 is the same camera as Porst’s CR-7). Because the market is so small,  prices for models tested and in working order can go up to  $150.
  • battery
    • Both cameras use the same 6v battery- still widely available today in alkaline, silver oxide and lithium variants. Silver Oxide is probably the best compromise.
    • None of the cameras works without a battery – no shutter release, no film advance – lots of people must have believed that their camera was broken when it was just asking for a new battery.
  • Lens selection
    • Canon: Abundant offer of great lenses at reasonable prices (Canon FD). Equally abundant offer of third party lenses, including in very exclusive brands like Angenieux.
    • Fujica: The AX-5 was launched in parallel to a new line of lenses, and none were really successful on the marketplace. Today, it is difficult to find anything which is not a 50mm or a 135mm lens. When you can find them, original Fujica X-Fujinon lenses with the renown EBC coating are expensive. Wide angle lenses or fast zooms are even more scarce and reach Leica R or Contax price levels.

Conclusion:

  • For an active film  photographer, it’s a no brainer – Canon A-1 cameras are abundant, lenses are easy to find and relatively cheap, and the A-1 is not inferior to the AX-5 in any significant way. The A-1 is the most satisfying pick in Canon’s “A” line, and the best choice in today’s comparison.
  • Fuji is a respected brand in the photography business (their medium format cameras and their current digital offerings have a cult like following). But Fuji’s aura does not extend to the Fujica AX cameras, who have lived an obscure life. For the collector of anything Fuji, the AX-5 is an interesting challenge: finding one that works is not super easy, and buying lenses is outright difficult. For an active photographer, the Fujica AX-5 has good sides: the camera is perfectly usable, it is light and compact, and presents simple and logical commands – but it does not feel as solid as the A-1, and looks more like a souped-up mid level SLR than a true enthusiast or pro camera. And in any case, because of the scarcity of X-Fujinon lenses,  – the real good ones have even become an object of speculation – none of the Fujica “X” cameras can be considered a reasonable choice for an active film photographer.

The Canon A-1 has a serious fan club, photographers who consider it the best film camera ever built. A few examples:

http://lewiscollard.com/cameras/canon-a-1/

https://www.casualphotophile.com/2015/04/20/canon-a-1-camera-review/


Rooftop terrace – Atlanta skyline – Fujica AX-5 – Tamron 28mm f/2.5 – Kodak Ektar

The most expensive manual focus SLRs of the 1980 generation

Film cameras are interesting objects. They appeal to collectors who will desire them for their historical importance, their pleasant esthetics, and for their scarcity, and to active photographers, who make their purchase decisions based on the feature set, the availability of good lenses, and the quality of the user experience.

The least desirable cameras (and therefore the cheapest) are characterized  by an abundant supply of working but unremarkable bodies with a meager selection of lenses, the most desirable by a limited availability of cameras in working order, combined with an interested set of features,  a pleasant user experience, and a broad selection of good lenses: in other words, cameras of great systems (Canon, Contax, Nikon, Leica, Olympus, for instance) that are scarce because they sold in small numbers, and/or because they did not age gracefully, with few of them surviving in working condition.

Let’s focus on the 4 Japanese brands I know best.

Canon

Manual focus Canon cameras were mass produced (Canon was the constant best seller except for a few years when Minolta took the lead), and generally reliable. Because the autofocus EOS product line is totally incompatible with the older manual focus cameras, users of autofocus Canon film cameras (and of modern digital EOS models) were not tempted to carry an old manual focus SLR in addition to their modern autofocus camera, and the offer of second hand manual focus cameras from Canon has always seemed to exceed demand. As a result, prices have tended to be low.

    • There is one glaring exception, the F-1, with nice copies proposed above $400.00 (Canon also produced limited editions to commemorate events like its  50th anniversary that command prices above $1,000). Another interesting Canon camera is the T90.
Canon T90 – LCD and control wheel – Source: Wikipedia
  • T90: the poster child of a second hand camera which checks all the marks, but is penalized by its lack of reliability:
    • On the plus side, it’s  very interesting from a historical point of view : it was designed with the input of Luigi Colani’ studio, and its ergonomics study is a precursor of the Canon EOS cameras and of almost all camera currently sold
    • Its sales volume was relatively limited  (for a Canon camera): it was an expensive high end camera, only sold for 2 years, when Canon had no autofocus camera to propose and was getting a beating from Minolta and Nikon on the marketplace.
    • The T90 was part of a very broad camera system, very popular with professional photographers. There is large supply of very good lenses, for cheap. Historical interest, relatively low sales volume, broad system – it should command high prices.
    • But on the other hand, the T90 did not age well: some of the components deteriorate if the camera is not used frequently, others have a limited lifespan, and Canon stopped servicing those cameras a long time ago – in fact, a lot of them display an “EEE” error and simply don’t work.
    • Therefore, there is not a strong demand for the T90. It commands prices starting in the $150.00 range for a tested model, which is less than what is asked for an  A-1 or even a AE-1 Program.

Fujica (the AX bayonet mount line) 

Fuji’s screw mount cameras sold in respectable numbers in the 1970s, and aged relatively well.  They were replaced in 1979 by a new generation of bayonet mount cameras  that did not sell very well and had reliability issues. A Fujica SLR such as the STX or the AX-3  in working condition is not as easy to find as a Canon AE-1 or a Nikon FE, for instance, but at the same time it does not qualify as exceptionally difficult to locate. The truth is that those cameras don’t seem to be interesting collectors (lack of aura) or active photographers (lack of lenses). Except maybe for the AX-5.

  • AX-5 – it was the full featured top of line, and was proposed at prices higher than the Canon A-1 it was supposed to compete with.
    • On the Plus side, it’s really a scarce camera. At any given time, no more than two or three are offered for sale on eBay, worldwide
    • On the Minus side, it’s not a very “interesting” camera: it’s a me-too product largely inspired by Canon’s A-1, with a toned down and more “feminine” design
    • the whole Fujica “X” product line has a reputation for being fragile (electronics)
    • there is very limited supply of lenses (good or bad), and the ones you can find are seriously expensive.
    • the market of second hand AX-5 cameras is too small – and there is not enough sales volume to establish a price of reference: I’ve seen working copies proposed above $150.00 but actual sale prices seem much lower.

Nikon

Nikon FA detail of the shutter speed knob and PSAM selector
Multi-Mode Automatic models tend to scare the active film photographers – they tend to prefer simpler models (here, the Nikon FA – which does not sell for more than the simpler FM2).

Very few Nikon cameras qualify as “scarce”. Nikon cameras generally sold in high volumes (within their class of products)  and are extremely reliable – a lot of them survived. Some of the cameras designed for professional photographers (the F3, the FM2) had production runs of almost 20 years. You will have to look for specific variants of a mainstream model such as the F3p or the F3AF to reach the level of scarcity that commands high prices (above the $1,000 bar). That being said, Nikon cameras of that vintage are very pleasant to use (they ooze build quality), they benefit from a huge supply of lenses and accessories (Nikon have been using the same bayonet mount since 1959, and the current flash system is downwards compatible down to the FE2 of 1983), and they take great pictures. They have a great usage value, but a limited collector’s appeal. A few exceptions:

  • F3: a regular F3 camera is becoming expensive – $200.00 to $400.00 for a nice one. The  F3P (a derivative for Press Photographers) sells in the $400.00 to $500.00 range, and the AF models of 1983 (with their dedicated viewfinder and lenses) can easily reach $1,200.00.
  • FM2 – the workhorse (or the perfect backup camera) of generations of Nikon photographers. Usable models are available below $200.00, while models popular with collectors (the FM2/T with a titanium body) start at approximately $500.00 to reach up to $1,500.
  • The FM3A was only produced for a few years, in small quantities. It’s a recent product with a high usage value (it’s an automatic which can also operate without a battery at any shutter speed) and it commands prices between $300.00 and $600.00.

Olympus

The Olympus OM-4 exposure controls – Source Wikipedia

In the 80s, Olympus had a line of low end “two digit cameras” (OM-10, OM-20, OM-30, OMG..) for amateurs and a line of single digit cameras (OM-2s, OM-4) for the discerning enthusiasts. The two digit cameras are extremely abundant, but unremarkable. The OM-2s and OM-4 are relatively easy to find, but are plagued by lousy battery management issues that limit their attractivity. At the end of their production life, the “single digit” cameras were upgraded to become “T” or Ti” models, which solved the electronics issues of their predecessors, and switched their brass top-plates for Titanium ones. Those T and Ti cameras are highly attractive for the active photographer (small size, unique light metering capabilities, broad system of lenses and accessories) and for the collector – they’re beautiful and are in limited supply. The OM-3Ti – the semi-automatic version- was produced in very limited quantities (6,000 units according to zone-10.com) and was selling at the same price as a Leica M6. The OM-4t and Ti had a long production run, but they were launched in the middle of the autofocus craze, when the large majority of the enthusiasts were busy converting their equipment to Minolta Maxxums, Canon EOS or Nikon N8008.

  • OM-3ti – proposed for any price between $1,200 and $4,000.
  • OM-4ti – proposed for any price between $250.00 and $800.00

Except for commemorative models (they often never leave the box they were shipped in), Leica SLRs models of all generations typically sell in the $200.00 to $800.00 range (the R4 are the cheapest, the R6.2 the most expensive). Contax models benefit from the aura of the Zeiss lenses, and sell in the same range as the Leicas.


Jules – French Bouledogue – Nikon F3 – Nikkor 135mm f/2.8 AI lens – Fujicolor 400

 

 

 

Stopped down or full aperture metering – why it still matters for users of mirrorless cameras today

For a single lens reflex camera or a lens manufactured after 1975, full aperture vs stopped down metering is a non issue. But it was a key differentiator between 1965 and 1975. And if you’re considering mounting an old lens (manufactured before 1975) on a mirrorless camera, it may still impact you.

On a single lens reflex camera (SLR), the photographer composes the picture on a mat focusing screen, where the image formed in the lens is projected. This layout has all sorts of advantages, but the viewfinder tends to get too dark for focusing when the lens aperture exceeds F/8, and at smaller apertures (F/11, F/16), even composition becomes impossible.

Therefore, the best practice in the 50’s was to open the lens at the widest aperture, focus carefully, and then rotate the aperture ring to stop down the lens at the aperture needed to expose the picture optimally. It worked, but it was slow.  The process was easy to automate, and that’s what aperture pre-selection systems do.

Aperture pre-selection mechanism

Their goal : let the photographer compose and focus at full aperture, and then stop down at the last fraction of a second, when he/she presses the shutter release. Practically, the diaphragm stays wide open, until the shutter release mechanism  (through various cogs, springs and levers) activates a rod in the lens which closes the diaphragm to the aperture pre-selected by the user.

Two implementations

  • manual pre-selection : the lens stays stopped down after the picture has been taken. The pre-selection mechanism has to be re-armed by the photographer if he/she wants to return to full aperture; it’s a slow process (shoot, rearm the shutter, rearm the lens).

    This big lever on this Nikkorex lens has to be pushed down to re-arm the pre-selection system after each shot
    This big lever on this Nikkorex lens has to be pushed down to re-arm the pre-selection system after each shot
  • auto pre-selection: the pre-selection mechanism does not need to be re-armed after each shot. The lens returns automatically to full aperture after each shot (that’s why lenses from the 1960-1975 period are often labeled “Auto”). It’s transparent for the user, who can operate faster and with a better chance of catching the decisive moment.

    M42 Lens mount - this lens is designed for "auto" preselection. It stays at full aperture until the pin is pushed to stop down position.
    M42 Lens mount – this lens is designed for “auto” preselection. It stays at full aperture until the pin is pushed to force the lens to a stop down position.

Through the Lens (TTL) metering

Aperture preselection solved the problem of composing and focusing at slow apertures, but the introduction of CdS cell meters to evaluate the illumination of a scene Through The Lens (TTL) brought a new set of challenges: the camera needed to know how open the diaphragm was going to be when the picture is finally taken. There were two ways to do it:

  • after the photographer had set the aperture, he had to press a dedicated lever to stop down the lens, and only then would the camera evaluate the illumination of the scene. It’s stopped down metering.
    Technically, it’s the quick and dirty answer:  the metering system of the camera does not need to know the value of the aperture pre-selected on the lens. It just measures the light going through the lens when stopped down. The pre-selection lenses don’t need to be modified – they simply work. But it’s cumbersome for the user:

    • it’s a step back – aperture preselection had removed the need for the photographer to stop down the aperture before pressing the shutter release. Now it needs to be done again.
    • the viewfinder is darker during metering (the photographer loses contact with the action, he can’t adjust the focus, and it’s difficult to see needle of the meter) – you cannot compose or focus and adjust the exposure at the same time.
    • it’s a disaster from an ergonomics point of view. Even in the best implementations, the photographer has to maintain the lens stopped down by pressing or lifting a dedicated lever on the camera’s body, while trying to turn the aperture ring or the shutter speed knob to adjust the exposure. You need three hands for this type of gymnastics.

      The Canon FT/QL and the Pentaxx Spotmatic SP both offer Stopped Down Metering. To determine the exposure, the photographer has to push the big switch to the left (Canon) or to lift the switch in the red circle (Pentax) - which is not a very natural movement. You wish you had three hands.
      The Canon FT/QL and the Pentaxx Spotmatic SP both offer Stopped Down Metering. To determine the exposure, the photographer has to push the big switch to the left (Canon) or to lift the switch in the red circle (Pentax) – which is not a very natural movement. You wish you had three hands.
  • full aperture metering is transparent for the user. The diaphragm is stopped down a fraction of a second before the shutter curtains open and the picture is actually taken. The lens stays at full aperture all the time, including during the exposure determination.
    But for full aperture metering to be possible, the lens has to communicate the aperture pre-selected by the user to the metering system in the camera body, so that it can determine the right shutter speed/aperture combination.
    Most vendors chose to add a new dedicated lever inside the lens mount (this solution was chosen by Canon, Minolta, Olympus and Pentax).

    Pentax K mount: Aperture control lever (i); Aperture simulator (ii): Source:pentaxforums.com
    Pentax K mount: Aperture control lever (i);
    Aperture simulator (ii):
    Source:pentaxforums.com

    A few other vendors chose to simply modify the design of the aperture ring of the lens, and use it to transmit the aperture value to the camera’s metering system. At the beginning, Nikon used an external fork (the “rabbit ears”) screwed at the periphery of the aperture ring to communicate the pre-selected aperture to a pin connected to the metering system in the body.

    Before the adoption of Auto-Indexing, Nikon lenses used a metallic fork ("the rabbit ears") to transmit the preselected aperture to the metering system of the camera.
    Before the adoption of Auto-Indexing, Nikon lenses used a metallic fork (“the rabbit ears”) to transmit the preselected aperture to the metering system of the camera.

    Later, Nikon redesigned the aperture ring to add  a small protruding tab at its back, and this tab moved a sensor on the circumference of the body’s lens mount (Nikon Auto Indexing or “AI” lenses). Nikon’s system is similar (in its principle) to Fuji’s implementation of full aperture metering on the m42 universal mount of the ST801 (pictures below).

Fujinon lens - the aperture ring is designed with a small tab which transmits the aperture pre-selected by the photographer to a rotating ring on the camera's body.
Fujinon lens – the aperture ring is designed with a small tab which transmits the aperture pre-selected by the photographer to a rotating ring on the camera’s body.
Fujica ST 801: Fuji's version of the m42 lens mount has a ring at the periphery - the little pin in the red circle is pushed by the tab protruding from the aperture ring of the lens. That's how the preselected aperture is transmitted.
Fujica ST 801: Fuji’s version of the m42 lens mount has a recessed, spring loaded rotating ring at the periphery – the little pin in the red circle is pushed by the tab protruding from the aperture ring of the lens. Any change to the pre-selected aperture on the lens will be transmitted to the camera.

Mounting an old lens on a mirrorless camera

When the photographer is using an old lens through a lens mount adapter, the cameras  needs to work with the lens stopped down (only semi-auto and  aperture priority automatic exposure modes are supported). There are none of the inconveniences associated with stopped down aperture on a reflex camera: on a mirrorless camera, the viewfinder always shows the image as it will be exposed, and if the exposure parameters (aperture, shutter speed and ISO) are correctly set, the image will be perfectly legible in the viewfinder, even if the lens is set a f/11.

But the challenge is to force an old lens to operate stopped down:

  • lenses designed for full aperture operations and stopped down metering (typically the m42 lenses with auto-pre-selection and the Canon FL) have a slider to switch off auto-preselection and operate permanently at stopped down aperture, in a manual mode. When mounted on a mirrorless camera through a lens mount adapter, they need to be switched to “manual”.
     Lenses of the 1965-1975 era often had an auto/manual switch - by default the operated at full aperture but could revert to manual if mounted on an older reflex camera.
    Lenses of the 1965-1975 era often had an auto/manual switch – by default they operated at full aperture but could revert to manual if mounted on an older reflex camera.

    The "manual" mode has to be switched on when used on a mirrorless camera.
    The “manual” mode has to be switched on when used on a mirrorless camera.
  • Nikon lenses  – the diaphragm of the Nikon lenses is opened at full aperture when the camera is mounted on a Nikon camera (the camera side of the mount has a lever which forces the lens open), but is stopped down when the lens is removed from the camera, or  mounted on an adapter deprived of the full aperture lever.  Which is perfect if you’re mounting the lens on a mirrorless camera.
  • Canon FD – when the lens is removed from a Canon camera, the diaphragm command is decoupled (the lens stays at whatever aperture it was pre-set the last time it was on a Canon FD camera). The adapter needs to be designed with a pin that will force the lens to stop down  when mounted on the adaptor.
Lens mount adapter for Canon FL/FD lens - the pin in the red circle pushes a lever on the lens and will force it to stop down.
Lens mount adapter for Canon FL/FD lens – the pin in the red circle pushes a lever on the lens and will force it to stop down.
  • Fuji’s EBC-Fujinon lenses are highly regarded, but the brand’s implementation of full aperture metering on the m42 mount presents two problems for modern mirrorless camera users:
    • most of the lens mount adapters receiving m42 lenses do not leave room for the aperture ring’s protruding tab of Fuji’s lenses. The lenses cannot be fully screwed down on the adapter and as a consequence may not focus to the infinite,
    • Fuji’s lenses don’t have a “manual” position and cannot be forced to operate stopped down on their own (that function was provided by the Fujica camera itself, not by the lens). There are work arounds to both issues, some nice, some ugly, but a lens mount adapter designed specifically for Fujica m42 lenses still has to be developed.

New-York City - Central Park - Fuji XT-1 - Canon 35-105 f/3.5 lens with Fotasy adapter
New-York City – Central Park – Fuji XT-1 – Canon 35-105 f/3.5 lens with Fotasy adapter