CamerAgX

February 9, 2017

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


January 22, 2017

How much did SLR cameras cost in 1985?

1985 is an interesting year, a turning point for the market of single lens reflex cameras: Minolta launched the first technically and commercially  successful auto-focus SLR, the Maxxum 7000. In a few years, manual focus SLRs would be relegated to the status of entry level models manufactured by subcontractors such as Cosina. Brands like Olympus or Contax would fail to impose their autofocus cameras on the marketplace and would become largely irrelevant, while vendors like Fuji would not even try to launch an autofocus line of bodies and lenses, and would leave the market altogether.

Old issues of Popular Photography have been scanned and indexed by Google, editorial content and ads. I compiled the table below from Adorama’s and Cambridge Photo’s ads.

Price of Cameras - 1985

Price of Cameras – 1985

A few interesting points….

Minolta Maxxum 7000 - source Wikipedia

Minolta Maxxum 7000 – source Wikipedia

  • the models most popular with enthusiasts  (Canon AE-1P and Minolta X-700) were in the $150 price range (body only).
  • Beginners could buy “a learner’s cameras” – with semi-auto-exposure – or a spec’d down aperture priority automatic cameras for less than $100.00.
  • Very few models were competing in the $300 price bracket: serious or wealthy enthusiasts and pros could buy the Nikon FA, splurge on an OM-4, or spend even more on modular cameras with interchangeable viewfinders  (like the Nikon F3, the Canon F1 or the Pentax LX).

The Minolta Maxxum 7000, priced at $300 (when you could find it), completely changed the equilibrium of the market. Targeted at the enthusiast photographer crowd (there was a more expensive Maxxum 9000 for the aspiring pros), it moved the average price of a camera a few notches upwards.

In a few years, the major vendors had converted their product line to autofocus, and relegated what was left of their manual focus SLR lines to the status of  low margin items targeted at impecunious customers. Minolta and Pentax moved the production line of their  manual focus SLRs to China, while Canon, Nikon and Olympus  commissioned companies  like Cosina to design and manufacture entry level manual focus cameras for them (Canon T60, Nikon FM10 and Olympus OM-2000 respectively).

On a side note, the Maxxum product line was so successful that Minolta leapfrogged Canon to become the #1 vendor on the market. It took Canon a few years (and the EOS series) to take their crown back.


Charleston, SC - Shot in 2009 - Nikon FM - Kodak CN400

Charleston, SC – Shot in 2009 – Nikon FM – Kodak CN400

March 13, 2010

A new 90mm lens from Voigtlander. Nikon and Pentax compatible

Filed under: Gear — Tags: , , , , , — xtalfu @ 12:00 am
voigtlander 90mm f:3.5 SL II announced

The Voigtlander 90mm f:3.5 SL II, as presented on CameraQuest's Web site.


Voigtlander is an old brand of German origin, now belonging to Cosina.


Cosina is a Japanese contract manufacturer – their 35mm cameras were adopted and sold successively by Canon, Olympus, Nikon, Contax and Zeiss, and they are one of the few companies still producing 35mm film cameras today. A few years ago, they started manufacturing manual focus prime lenses, available in the Canon EF, Pentax K and Nikon F (AI-S) mounts under the Voigtlander brand.


The lenses made for Nikon cameras had one limitation, though. While perfectly compatible with manual focus SLRs, they did not have the electronic chip and the electrical contacts needed to communicate with recent autofocus bodies. Like Nikon’s own AI-S lenses, they could be mounted on mid-level dSLRs like the Nikon D80 or D90, but they were not recognized by the camera, which disabled its exposure metering circuit and forced the photographer to use a hand-held exposure meter, or to rely on the analysis of the histogram, after the picture was taken. The lens mount of higher end Nikon models such as the D300 or the D700 still has the pins, levers and springs needed to be fully AI-S compatible.


The new generation of Voigtlander SL II lenses has the right chip and the right electrical contacts, and is now compatible with any Nikon autofocus SLR or dSLR (the photographer still has to focus manually, of course).


A few days before the PMA, Cosina presented the APO-Lanthar 90mm f:3.5 SL II Close Focus lens (yes, that’s its name), a compact close focus lens. It targets a small niche of photographers who still want to buy new manual focus equipment. With a maximum aperture of F:3.5, it’s pretty slow compared to Nikon’s 85mm f:1.4 prime, and will not compete in the “portrait lens” category. With a magnification ratio of 1/3.5, it’s not a macro lens either. It’s available in Nikon and Pentax mounts, but non in Canon’s EF.


A product for a niche within a niche, obviously.


More about the Voigtlander APO-Lanthar 90mm f:3.5 SL II Close Focus


Cameraquest: the distributor of Voigtlander SLII lenses


March 9, 2010

Viewfinders: coverage, magnification and eye relief

Filed under: Gear — Tags: , , , , , , , , , , — xtalfu @ 11:50 pm
Eye Relief

Eye Relief


A large proportion of photographers wears prescription glasses – I know, I’m one of them – and almost everybody wears sun glasses occasionally. But surprisingly, until high eye point or high eye relief viewfinders appeared – on the Nikon F3 HP in the early eighties, photographers with glasses could not see the integrality of the scene – let alone the aperture or speed information on the LED displays surrounding the view of the scene- without having to move their eye balls up and down and left to right.


As far as viewfinders are concerned, some cameras are better than others, though. The quality of the viewfinder of a manual focus camera is influenced by three factors:

  • Coverage: It’s the percentage of the image captured through the lens which is going to be shown in the viewfinder. 100% coverage is desirable – but expensive to manufacture, and only top of the line cameras (the real “pro” models) show the integrality of the scene in the viewfinder. Most SLRs show between 85% and 95% of the scene. Point and shoot cameras, (more precisely the few P&S which still have an optical viewfinder) are much worse. The best of them, the Canon G11 only shows 77% of the scene that will be captured through the eye piece.

  • Magnification: If the magnification was equal to 1, an object seen through the viewfinder would appear to be the same size as seen with the naked eye (with a 50mm lens on a 35mm camera). The photographer could even shoot with both eyes open. If the magnification ratio is lower than 1, then the object will appear smaller in the viewfinder than seen with the naked eye.


    Magnification has an impact on composition and focusing. If the magnification ratio is very low (below 0.4) the image becomes so small that it’s difficult to compose the picture. Magnification is also a critical factor for picture sharpness on manual focus cameras: the accuracy of the focusing is directly related to what the photographer can see on the matte focusing screen, and the higher the magnification, the easier it’s going to be for him or her to focus accurately.


    On a 35mm single lens reflex camera, the magnification is measured with a 50mm lens, and varies between 75 and 95%. Full frame digital SLRs have viewfinders offering comparable magnification values. dSLRs with so-called APS-C sensors advertise very high magnification ratios, but after the crop factor of the small sensor is taken into consideration, the real magnification value lies between 0.46 and 0.62. Read Neocamera‘s article for more information about the real viewfinder magnification ratio of dSLRs.

  • Eye relief: “The eye relief of a telescope, a microscope, or binoculars is the distance from the last surface of an eyepiece at which the eye can be placed to match the eyepiece exit pupil to the eye’s entrance pupil.” (Wikipedia, eye relief entry).The longer the eye relief, the more comfortable the camera is going to be for a photographer wearing glasses, but the smaller the focusing screen is going to look.


    A photographer wearing glasses will need an eye point of approximately 20mm (depending on the dimensions of the frames and the thickness of the lenses of the glasses) to be able to see entire the viewfinder image, plus the exposure information without having to move his eye balls left to right and up and down. Camera manufacturers describe them as “High eye Point” or HP viewfinders.


  • A comparison between a few 35mm cameras


    As is often the case with engineering, a good design is the result of a successful compromise between conflicting requirements. Most photographers desire a long eye relief, but at the same time want a magnification ratio high enough, so that they can compose their image with precision and focus accurately. With the F3, Nikon offered 2 versions of its standard viewfinder. The DE-2 of the original F3 had an eye relief of approximately 20mm, and a magnification of 80%; the DE-3 viewfinder of the F3 HP had a much longer eye relief (25mm) but a smaller magnification ratio of 75%. The market decided in favor of the longer eye relief and the DE-3 became the standard viewfinder of all subsequent versions of the F3. The advent of autofocus SLRs accelerated the trend towards longer eye relief and lower magnification ratios.

    =

    Model Coverage Magnification Eye Point Comment
    Nikon F3 HP (DE-3 finder) 100 % 75% 25mm The camera that introduced Hight Point viewfinders to the public.
    Nikon F3 with the standard DE-2 viewfinder 100 % 80% Not known. Probably 20mm The original pre-HP viewfinder. Even with glasses one can easily see all of the scene and the little LCD display.
    Olympus OM-1 97% 92% Not known. Probably 15mm Incredible. How can such a small camera deliver such a large image? Short eye point, but since the viewfinder does not provide any exposure information at the periphery of the frame, not much of a problem.
    Nikon FM, FE, FE2, FA 93% 86% Not known. Probably 14mm Short eye point, plenty of information at the periphery of the viewfinder. Not the best recipe for photographers wearing glasses.


    Subjective results


    The experience confirms the figures. The Nikon F3 has by far the best viewfinder, followed by the tiny Olympus OM-1. The Nikon FM-FE-FA are far behind.

  • Nikon launched the F3 with a standard viewfinder (model DE-2) which offered 100% coverage and already had a relatively long eye point. The standard F3 can comfortably be used by photographers wearing glasses. A few years later, Nikon introduced another version of its flagship camera, the F3 HP, which was the first to offer a viewfinder with the very long eye point of 25mm (one inch). The long eye point came at the cost of a lower magnification (down to 75%) and an higher weight. The F3 HP was a sales success, and all subsequent F3 cameras would come from Nikon with the HP viewfinder (the DE-3).
  • The Olympus OM-1 has an incredible viewfinder, with a very high coverage and a very high magnification. The viewfinder does not offer any exposure information besides the match-needle arrangement at the right of the image, and even if the eye point is rather short, the photographer has the impression he’s watching all of the scene. Subsequent OM models offered a little more information at the periphery of the viewfinder and a little less magnification, and in a world where hi-point viewfinders were becoming the norm, they were far less remarkable than the OM-1.
  • The Nikon FM, FE and FA provide more exposure information than the Olympus cameras (the selected aperture, in particular). Compounded with the very short eye relief (14mm), it makes it impossible for a photographer wearing glasses to see the whole scene and the exposure information at the periphery without some eye movements. While similar on paper to the other compact Nikon SLRs, the viewfinder of the Nikon FG fares worse than its stablemates in real life.


    Other cameras


    Rangefinder cameras work by different rules. Their viewfinder covers far more than what will be captured on the film, and very little exposure information is displayed in the viewfinder. Even if the Leica M offers an eye relief of only 15mm, a photographer wearing glasses will not have any problem visualizing the image in the viewfinder.


    With a few exceptions such as the Canon G11, Point and Shoot digital cameras don’t offer optical viewfinders anymore. The G11’s may be used as a last resort in a very bright environment, (when using the LCD is not an option), but it’s very small and very unpleasant to use. Low end digital SLRs with small sensors (Four Thirds or APS-C) are equipped with very low magnification viewfinders, and have a very pronounced tunnel effect. Manual focusing is not an option, and composing an image with precision can be challenging. Mid-level dSLRS (like the Canon 7D or Nikon’s D90 and D300) have much better viewfinders, with relatively long eye relief (22 and 19.5mm respectively) and real magnification ratios of approximately 0.625.



    More about it


    Luminous Landscape – Mike Johnson’s “Understanding SLR viewfinders”


    Neocamera: Viewfinder of digital cameras


    Foca *** with a Foca turret viewfinder / Olympus OM-1n. The Foca is a French rangefinder camera from the late forties, and its viewfinder is unasable if you wear glasses. And hardly usable even without them.

    October 7, 2009

    50 Years of Lens Mount Evolution – Part IV of VI

    Filed under: Gear — Tags: , , , , , , , , — xtalfu @ 10:00 pm


    Programmed exposure


    The automatic bodies of the early seventies still required some input from their users: they could only determine the shutter speed (or the aperture in the case of Canon cameras) after the photographer had set an aperture (or a shutter speed) compatible with the film speed, the intensity of the light and the characteristics of the scene (portrait, action shots, macro, and so on).
    If the aperture set by the user was too low or too high, a matching shutter speed could not be selected by the camera and the picture was hopelessly under or over exposed.
    Similarly, if the photographer let the camera select a very slow shutter speed with a long tele-lens, the picture would be blurry and unusable. Trained photographers knew that. But a better automatic exposure solution had to be found for the photographers who did not want to be bothered with technical details.

    Nikon FA - the commands for the multi-mode exposure automatism (PSAM)

    Nikon FA (1984) – the command for the multi-mode exposure automatism (PSAM) is in front of the shutter speed knob


    Inspired by the program modes already available in point and shoot cameras, Canon launched the A-1, a new SLR with programmed exposure modes in 1978. Practically, it meant that the auto exposure system of the body had to simultaneously command the shutter speed and the aperture of the diaphragm.


    Canon did not have to change anything on the FD mount, which had been created for full aperture shutter priority exposure. 


    Nikon introduced the “AI-S” generation in 1979 when the mount was modified to support a linear command of the diaphragm. The first Nikon cameras to take advantage of the AI-S lenses and to offer a program mode and shutter priority were launched in 1982 and 1984 respectively. Because the camera body was informed of the focal length of the objective, it could choose automatically between two aperture-speed combinations when configured in program mode, one for wide angle and normal lenses, and one for lenses of 135mm and longer .

    Nikon F mount - AIS on the Nikon FA

    The AI-S variant of Nikon F mount, shown here on the Nikon FA. Compared to the lens mount of the FE2, the FA’s is using three more sensors: a small pin above the lens lock – which informs the body that the lens is of the AI-S type, a larger sensor inside the reflex chamber (right of the picture, in the middle) which is used to transmit the focal length of the lens to the body, and a slider at the bottom of the reflex chamber, used to transmit the maximum aperture of the lens to the body. The use of mechanical sensor had reached its limits. It was time to adopt electrical contacts instead.

    Nikon F mount - AI on the Nikon FE2

    For reference, the much simpler design of the AI mount (Nikon FE2). The stop down lever controlling the diaphragm is on the left side on the picture. You can still find it on current Nikon digital cameras.


    Still trying to catch up with Nicanolta, Pentax adopted a brand new bayonet mount, the K mount, in 1975. The first K mount, however, did not support shutter priority or program modes. Electric contacts would have to be added with the KA declination of the K mount in 1983 to make it possible. Its close derivatives are still used today on Pentax DSLRs.


    The state of the art between 1971 and 1985


    Pentax: Aperture priority automatic cameras launched in 1971 with modified 42mm screw mount lenses supporting full aperture metering.
    Change from the 42mm screw mount to a new Pentax K bayonet in 1975 (automatic pre-selection, full aperture metering, transmission of the pre-selected aperture value from the lens to the body);
    Shutter priority and program mode introduced in 1983 with the KA version of the K mount.


    Canon: The FD breech mount introduced in 1971 was ready for the Shutter priority cameras launched in 1973 (Canon EF) and for the program mode (Canon A1, 1978).


    Minolta: MD declination of the SR Mount (one pin added for the support of the Shutter priority mode) to support the Shutter priority mode in 1977.


    Nikon: Aperture priority cameras available since 1971 (Nikon EL) with the manual indexing F mount. Launch of the AI version of the F mount in 1977 to improve the ease of use. Progressive adoption of the AI-S declination of the F mount in 1979 to prepare for the arrival of cameras offering a program mode (Nikon FG, 1982) and a shutter priority automatic exposure (Nikon FA, 1984).


    Olympus: the OM mount was introduced in 1971, and was ready to support programmed exposure from the beginning.



    More about the lens mounts


    Photography in Malaysia: information related to the F lens mount


    American Petit LeMans - the Atlanta Pipe Band. Nikon FA - Kodak CN400

    American Petit LeMans – the Atlanta Pipe Band. Nikon FA – Kodak CN400 – Processed by Costo. Cropping and minor adjustments in Lightroom 2

    March 10, 2009

    Viewfinders: coverage, magnification and eye relief (Intro)

    Filed under: Gear, Intro — Tags: , , , , , , , , — xtalfu @ 12:30 am
    Eye Relief

    Eye Relief


    A large proportion of photographers wears prescription glasses – I know, I’m one of them – and almost everybody wears sun glasses occasionally. But surprisingly, until high eye point or high eye relief viewfinders appeared – on the Nikon F3 HP in the early eighties, photographers with glasses could not see the integrality of the scene – let alone the aperture or speed information on the LED displays surrounding the view of the scene- without having to move their eye balls up and down and left to right.


    As far as viewfinders are concerned, some cameras are better than others, though. The quality of the viewfinder of a manual focus camera is influenced by three factors:

  • Coverage: It’s the percentage of the image captured through the lens which is going to be shown in the viewfinder. 100% coverage is desirable – but expensive to manufacture, and only top of the line cameras (the real “pro” models) show the integrality of the scene in the viewfinder. Most SLRs show between 85% and 95% of the scene. Point and shoot cameras, (more precisely the few P&S which still have an optical viewfinder) are much worse. The best of them, the Canon G11 only shows 77% of the scene that will be captured through the eye piece.

  • Magnification: If the magnification was equal to 1, an object seen through the viewfinder would appear to be the same size as seen with the naked eye (with a 50mm lens on a 35mm camera). The photographer could even shoot with both eyes open. If the magnification ratio is lower than 1, then the object will appear smaller in the viewfinder than seen with the naked eye.


    Magnification has an impact on composition and focusing. If the magnification ratio is very low (below 0.4) the image becomes so small that it’s difficult to compose the picture. Magnification is also a critical factor for picture sharpness on manual focus cameras: the accuracy of the focusing is directly related to what the photographer can see on the matte focusing screen, and the higher the magnification, the easier it’s going to be for him or her to focus accurately.


    More after the jump


  • Blog at WordPress.com.