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  1. #21

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    Quote Originally Posted by mtbbrian View Post
    This whole issue is so confusing to me!
    I guess with RF's you can't have it both ways with one body.
    Right?
    How many bodies does your "average RF shooter" have?
    As I have stated, I'd like to have lenes from 25 to 75 or 90.
    Brian

    Yes it is confusing . . . at least when it's new to you.

    You can have it both ways with one body. A split image rangefinder is is an instrument that determines the distance of an object from the camera by taking two different images of the object at separated points equidistant from the object & by then merging those images through an optical system in the camera. When they merge into one image, the distance & therefore accurate focus has been determined. Accuracy of rangefinder focusing depends on two factors: how widely spaced the two images are & how highly magnified the image in the viewfinder is. The wider spaced the two images are, the easier it is to make fine adjustments & therefore to be more precise in determining the exact right point for focus. The higher the magnification, the easier it is to see the image & therefore to edetermine when the two images are exactly merged in the viewfinder.

    Telephoto lenses have shallow depth of field & therefore require greater precision to focus. Wide angle lenses have much more depth of field & with so much of the subject in focus, less precision is requirted.Wide apertures have less depth of field, so greater precision is also required to focus at very wide apertures (greater than f/2) than at smaller apertures. A more precise rangefinder is always an asset because it is easier to focus at any focal length.

    Versatile rangefinder cameras that can work well with both wide angle & telephoto lenses usually use a magnification of about 0.7 magnification, i.e. the image that you see in the viewfinder will be reduced to .7 times the size that you would see with the naked eye. magnifications greater than .7 will make it easier to focus but the size will be too great to view the entire field of view that the camera sees with a wide angle lens. Magnifications less than .7 will accomodate an increased field of view but will be harder to focus because you will be viewing a smaller image. Using .7 as a compromise allows for the use of a wide range of focal lengths, such as the range in which you are interested.

    Leica has long been the standard in rangefinder photography & uses a magnification of .72 & a rangefinder with a base line 49 mm long on its basic model. Its viewfinder includes frame lines for focal lengths from 28 mm to 135 mm. The Zeiss Ikon, which was introduced a year ago, tweaked this formula by lengthening the base line to 75 mm & increasing the magnification to .74 to obtain greater focusing precision. By using an oversized eyepiece, they were still able to include frame lines for the 28 mm focal length.

    The Voigtlander Bessa cameras which have been discussed in this thread start with a limitation in that the base line of their rangefinder is only 37 mm long, or half the length of the one on the Zeiss Ikon. This saves on cost, but limits the accuracy of focus - especially under certain conditions (telephoto lenses & wide apertures) when using their basic R2 camera with .68 magnification. To offer an alternative to their customers, two years ago they introduced the R3 with 1.0, or life size, magnification to improve focusing precision. However, the widest frame lines they could fit in their viewfinder was for the 40 mm focal length & most have found even those to be very difficult to see. In April, they will offer the R4 with magnification reduced to .52 to accomodate lenses as wide as 21 mm.

    Leica does offer an option of .58 magnification to make the 28 mm frame lines easier to see, which is especially useful for those with glasses. However, they have not attempted to introduce 24 or 21 mm frame lines into such a viewfinder. So, what Cosina is attempting will be an innovation. When the camera is available, photographers will be able to report how difficult or easy it is to work with these wider frame lines. What is currently availbale on rangefinder cameras for focal lengths wider than 28 mm is the use of an auxiliary viewfinder that is added to the camera by mounting it on the hotshoe. This requires that the lens be focused through the camera's built in viewfinder & that the photographer then switch to the auxiliary finder to compose the picture. This two-step process is obviously not as efficient as doing both through the same viewfinder, so photographers often estimate focus & set the focus by the distance scale on the lens - often in advance of actually taking the picture. Because there is great depth of field at these focal lengths, such estimates can achieve accurate focus & leave the photographer free to compose through the auxiliary finder & with focus pre-set, ignore the camera's viewfinder. Photographers have been using this method for 50 years & auxiliary viewfinders are so basic on lenses wider than 28 mm that they are often included with the lens for the purchase price.

    You can find more information on rangefinder cameras & their viewfinders at the following websites:

    www.photozone.de/3Technology/camtec2.htm

    http://www.photoethnography.com/Clas.../focusing.html

    www.cameraquest.com/leica.htm

  2. #22

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    Quote Originally Posted by Lee L View Post
    You're going to file a full report on the emulsion here first, right?

    Lee
    Well, probably www.rogerandfrances.com with a cross-link here. On VERY limited acquaintance (a couple of square feet or so) it looks like sheer magic. I'm waiting for a lot more line-coated film for a better test.

    Cheers,

    R.

  3. #23

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    Quote Originally Posted by Biogon Bill View Post
    Prototype or pre-production model.
    Not a lot of difference. The only real variation is the vf (the rest of the body is totally known) and there's not a lot to change between the prototype/pre-production camera and the final production version.

    Personally -- and I speak as someone who regards 35mm as a 'standard' lens -- I'd only buy one if I never used 75mm or 90mm, or switched to reflexes for 50mm and above. If that applies to you (or anyone else), it's an easy choice.

    Incidentally, superb analysis of effective base length/frame size. I'm sure many will find it invaluable.

    Cheers,

    R.

  4. #24

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    Quote Originally Posted by Biogon Bill View Post
    How can it be a "known" commodity when no one has had the opportunity to use one yet? We know some stats about it & we know its siblings, but we don't really know this camera yet.
    True -- from prototype to actual camera, things change, although maybe it's very close to being a production model.

    The point is that it probably hasn't been in anyone hands long enough for people to offer significant opinions or at least to offer more than "first impressions."

    I look forward to some in-depth reviews.

  5. #25

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    Quote Originally Posted by mtbbrian View Post
    From the Leica's I have looked at, the M6 and M7, that information is engraved on the viewfinder on the front.
    Brian
    Brian, I've been looking carefully at my M6 and I cannot see any engraving on the viewfinder on the front. I would like to find out what I have.

    All the best,
    Sam H.

  6. #26

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    Quote Originally Posted by elekm View Post
    The point is that it probably hasn't been in anyone hands long enough for people to offer significant opinions or at least to offer more than "first impressions."

    I look forward to some in-depth reviews.
    Thanks, Mike. That was exactly my point.

    A magnification of .52 isn't that far off a Leica M with .58 mag & yet Leica never saw fit to include frame lines for 24 much less 21. I'm waiting to see how workable those frame lines actually are - especially the 21. For me the question is whether the benefits of focusing/composing in a single VF will outweigh the benefits of a custom auxiliary VF at a focal length for which precise focusing isn't a big issue.

  7. #27

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    Quote Originally Posted by Samuel Hotton View Post
    Brian, I've been looking carefully at my M6 and I cannot see any engraving on the viewfinder on the front. I would like to find out what I have.

    All the best,
    Sam H.
    Check the hot shoe. There might be a number engraved on one of the rails.

  8. #28

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    Quote Originally Posted by elekm View Post
    Check the hot shoe. There might be a number engraved on one of the rails.
    Good evening Elekm,
    Had a good look on the hot shoe, the only number is the serial number 1794xxx.

    Have I got a unusual M6 or what? I'm stumped!!!

    Sam H.

  9. #29

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    Not sure about the rarity of your M6. Actually, I forgot that you should be able to tell the viewfinder magnification by the framelines that you can see.

    According to CameraQuest:

    -- The .72x finder displayed 28/35/50/75/90/135

    -- The .58x finder displayed 28/35/50/75/90

    -- The .85x finder displayed 35/50/75/90/135

  10. #30

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    Quote Originally Posted by elekm View Post
    Not sure about the rarity of your M6. Actually, I forgot that you should be able to tell the viewfinder magnification by the framelines that you can see.

    According to CameraQuest:

    -- The .72x finder displayed 28/35/50/75/90/135

    -- The .58x finder displayed 28/35/50/75/90

    -- The .85x finder displayed 35/50/75/90/135
    Good morning elekm,
    Thank you very much for the GREAT information. I have the .72x finder.
    All the best,
    Sam H.

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