Viewfinders: coverage, magnification and eye relief

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.

    Single Lens Reflex or Rangefinder Camera? A few days with a Leica CL


    I was back in Paris for a few days at the end of last year, and since there was still room in my equipment bag, I pulled my old and battered Leica CL from a drawer and took it with me. A good opportunity to check whether I could get acceptable results out of it this time.


    I never was a rangefinder guy. When I started being interested in photography, semi-automatic Single Lens Reflex cameras (SLRs) were already the norm, and Leica an expensive brand of obsolete cameras. My formative years were spent with a Pentax MX, and I’ve always found natural to see the world on the matte focusing screen of a reflex camera. But I was intrigued by the Leica legend, and one day, purchased a Leica CL. Over the last 15 years, I used it rarely, but being light and compact, it could find a slot in my equipment bag from time to time.

     

    Leica CL with its two lenses
    Leica CL with its two lenses

    The CL was a sort of entry-level rangefinder camera, designed by Leitz in Germany and built by Minolta in Japan from 1973 to 1976.


    From a technical point of view, it is a miniature M5, and very advanced for a Leica of its time. A semi-auto camera with through the lens metering, it used a mechanism very similar to the system used in the much maligned M5’s.


    After the CL and the M5 were abandoned in the mid seventies, Leitz reverted to fully manual cameras with no metering capabilities, and aficionados had to wait for another 10 years before a semi-auto rangefinder camera was proposed again by the German firm.


    With its M bayonet mount, the CL could use the 50 mm lenses of its bigger brothers, but Leitz had also designed two lenses specifically for the CL, a 40mm Summicron (F:2) and a 90mm Elmar (F:4).

    Using the Leica CL


    A true Leica, it also used a focal plan textile shutter (1/2 sec up to 1/1000 sec). The rangefinder has a short base and is not as accurate as the M6’s, but is good enough for the 90mm Elmar.

    A class at the Louvres Museum- Jan.2010. Paris
    A class at the Louvres Museum- The CL is small and silent, and nobody paid attention to me or to the camera.


    With its mechanical shutter, the CL only needs a battery for metering, and uses it sparingly. Mine still has the mercury battery I bought it with, but I suspect it must be at the end of its life, because the recommendations of the metering system were so bizarre that I decided to forget about it and apply the “sunny 16” rule. With a battery in working order, the determination of the exposure is very simple (a match needle at the right of the viewfinder).


    On the CL, the image in the viewfinder is large and clear. The viewfinder has a greater field of view than the 40mm lens normally mounted on the camera, and projected bright lines show to the photographer what the actual picture will look like. There is little difference between the respective field of views of the viewfinder (similar to a 35mm) and of the 40mm lens, but the bright frame projected of the 90mm lens will seem minuscule at the center of a viewfinder, whose enlargement factor does not change. Disconcerting, but not dramatic.


    What really requires adaptation is focusing. On a manual focus Single Lens Reflex camera, the image of the subject is projected on a matte ground glass, and the photographer can see immediately whether the image is in focus or not. Similarly, with tele-zooms used at large apertures, the effects of the reduced depth of field are easily visible, and the photographer can visualize what will be in focus, and what will be pleasantly blurred.

    The back of the Leica CL
    The back of the Leica CL – Note the viewfinder at the top left corner of the body, leaving ample space for the nose of the photographer


    On a rangefinder camera, the finder does not provide any feed-back when it comes to focusing. Every element of the image seems in focus: it’s very easy too forget to set the focus, and very difficult to predict the depth of field.


    The coupled rangefinder is materialized by a small window at the center of the viewfinder. It’s extremely accurate, but the focusing ring on the small lens is narrow and rather stiff, and you get the impression that you could have reacted much faster with the large focusing ring of the 50mm lens of your SLR.


    I guess it gets better with experience, but it’s very frustrating for a beginner.


    If you can get over the idiosyncrasies of the viewfinder, the Leica experience is very rewarding. The camera is virtually silent, and being small and black, gets totally unnoticed. The pictures are sharp, with a lot of micro-contrast, and give the impression of being of higher quality than the images taken with most of the SLRs (provided you could master the focusing system). Your success rate will be lower than with a manual SLR, and far lower than with a dSLR of the latest generation, but when the images are good, they’ll be very good.


    Buying a rangefinder camera


    Rangefinder cameras are markedly different from SLRs, and will not produce good pictures without some serious practice. The first attempts will be frustrating, and there is no point in spending a lot of money in a Leica M9 if you discover after a few days that you’re totally allergic to this style of cameras.


    The Leica CL is one of the cheapest options for a photographer who would like to try rangefinder cameras. Good Leica CL are rather easy to find in the US or in Europe. Even in a pristine condition, they never cross the $1,000 threshold, and nice items can be found between $300 and $600. In Japan, the CL was sold as a Leitz-Minolta camera, with no other difference with the “Leitz only” CL than the logo.


    A few years after the production of the CL was stopped, Minolta launched the CLE, an automatic exposure version of the CL, and the first camera to propose On the Film (OTF) flash metering. There is no semi-auto or manual mode. The CLE contains much more electronics than the CL, and it can not be repaired if the main circuit decides it had enough. The CLE is much more difficult to find than the CL. Expect to pay $600 for a nice one, and thousands for collector editions.


    Full size M series Leica are either more primitive (no exposure metering) or more recent and significantly more expensive than the CL. Even in poor condition, a Leica M6 can not be found for less than $1,000. Cosina is still producing a line of rangefinder cameras, sold under the Voigtlander brand, and available with Leica M lens mount as well as less common mounts such as the Nikon and Contax rangefinder mounts. Amongst all the the rangefinder cameras from Voigtlander, the Bessa R3M is the closest to the CL (it accepts the same 40 and 90mm lenses), and can be found between $400 (used) and $600 (new).

    Leica CL - The shutter is not armed
    The light chamber of the Leica CL – In this picture, the shutter is not armed. As a consequence, the CdS sensor of the exposure meter is not deployed.
    Leica CL -Armed shutter
    The shutter is armed; the CdS sensor of the exposure meter is deployed. It will retract when the shutter release is pressed, just before the shutter opens.


    References and links


    A specialized source for rangefinder cameras (Leica, Nikon and modern Voigtlander): http://www.cameraquest.com/leicacl.htm


    Canal St Martin - Paris - Located between the Gare de l'Est and the Bastille, the canal was a favorite set of the French film makers in the thirties. Using a Leica with B&W film seemed appropriate.
    Canal St Martin – Paris – Located between the Gare de l’Est and the Bastille, the Canal was a favorite set of the French film makers in the thirties. Using a Leica with B&W film seemed appropriate