kermaier
Well-known
Anyone know whether an external viewfinder intended for a 50mm lens on a 35mm RF camera would be suitable for use on a 6x9 folder with a 105mm lens?
Thanks,
Ari
Thanks,
Ari
50mm for 35mm external finder on 6x9
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jingles_97
Established
105mm on 6x9 wide is roughly 42mm on 35mm.
xwhatsit
Well-known
It'd be close, but the trouble is that whilst 105mm is very close to the theoretical `normal' lens of 90mm x 60mm, 50mm is in fact slightly longer than normal on 36mm x 24mm.
The diagonal of 6x9 is 108mm or thereabouts. The diagonal of 35mm is actually roughly 43mm instead of 50mm as you'd expect. The reason for this... well according to Wikipedia, Barnack chose it `as a compromise between the theoretical value and good sharpness, as lens technology at the time was such that slightly longer focal lengths were able to achieve optimum sharpness.'
If you divide the diagonals together, you work out the multiplier to get equivalent focal lengths; 108mm / 43mm = 2.5 or so. 2.5 * 50 = 125. So your 50mm finder would be showing approximately the view you'd get with a 125mm lens on a 6x9 camera.
However, given the horrible viewfinders on most 6x9 folders (my Agfa Record III is appalling!), the 50mm finder would probably still give better framing accuracy anyway! You'd get a touch extra on your negative than you might expect but with 6x9, resolution isn't exactly an issue, and if it's a nice bright-line finder then you could look outside the framelines a fraction anyway.
You can check viewfinder accuracy with some frosted tape or ground glass across the film gate. Point camera at a wall, use bits of black tape on the wall to mark out the corners of the viewfinder and check results on the ground glass.
The diagonal of 6x9 is 108mm or thereabouts. The diagonal of 35mm is actually roughly 43mm instead of 50mm as you'd expect. The reason for this... well according to Wikipedia, Barnack chose it `as a compromise between the theoretical value and good sharpness, as lens technology at the time was such that slightly longer focal lengths were able to achieve optimum sharpness.'
If you divide the diagonals together, you work out the multiplier to get equivalent focal lengths; 108mm / 43mm = 2.5 or so. 2.5 * 50 = 125. So your 50mm finder would be showing approximately the view you'd get with a 125mm lens on a 6x9 camera.
However, given the horrible viewfinders on most 6x9 folders (my Agfa Record III is appalling!), the 50mm finder would probably still give better framing accuracy anyway! You'd get a touch extra on your negative than you might expect but with 6x9, resolution isn't exactly an issue, and if it's a nice bright-line finder then you could look outside the framelines a fraction anyway.
You can check viewfinder accuracy with some frosted tape or ground glass across the film gate. Point camera at a wall, use bits of black tape on the wall to mark out the corners of the viewfinder and check results on the ground glass.
ZeissFan
Veteran
I tend to frame a bit loose with 6x9, having been burned in the past because of parallax.
kermaier
Well-known
OK, thanks for the info! Sounds like a 50mm external VF would be much better than the built in VF on a Bessa II.
Ari
Ari
Ezzie
E. D. Russell Roberts
Find one with parallax correction. Personally I´d get a varifocal finder, you´ll be able to adjust it to your needs, discretely adjustable as they are.
kermaier
Well-known
Are there any bright-line veridical finders? (Being able to see around the frame is one of the things I like best about RFs.)
Roger Hicks
Veteran
Sort of. There's a Wray copy of a VIOOH (or possibly VIDOM -- it's years since I had one) with transparent yellow masks instead of opaque. As soon as you try it you realize how much better an idea it is than the Leica design.
The other trick is to learn to keep both eyes open. Or of course to buy one of the Voigtländer or Kirn finders where you HAVE to use both eyes.
Cheers,
R.
Ernst Dinkla
Well-known
Right, I use an external 35mm focal length viewer for 35mm on a Kodak Monitor (56x82mm frame) and on the Bessa I (56x88mm frame). It suits the last best.
Acall 35mm viewer with a -4 dioptrie lens added in a custom eyecup.
Ernst Dinkla
New: Spectral plots of +180 inkjet papers:
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
As a couple other options, there's a Voigtlander branded 40mm finder, not too common but it was offered. And Pentax supplied a 43mm finder with its RF lens of that focal length. Something to search out, perhaps.
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