sar-photo
Simon Robinson
What's the widest lens you can use on 6x12 that doesn't need a centre filter?
6x12cm is equivalent to 2.2x4.7 inches.
I'm hoping to get a 6x12 with a Rodenstock 65mm lens which has an image circle of 170mm @ f22. I have done a drawing and I can see from it that you would definitely need to use a center filter with that focal length on 4x5, but it looks as though it should be ok with 6x12 - does anybody have any experience with this format/lens combination?
Is it correct that as you open up the aperture that the image circle gets smaller?
Cheers
Simon
6x12cm is equivalent to 2.2x4.7 inches.
I'm hoping to get a 6x12 with a Rodenstock 65mm lens which has an image circle of 170mm @ f22. I have done a drawing and I can see from it that you would definitely need to use a center filter with that focal length on 4x5, but it looks as though it should be ok with 6x12 - does anybody have any experience with this format/lens combination?
Is it correct that as you open up the aperture that the image circle gets smaller?
Cheers
Simon
Roger Hicks
Veteran
Dear Simon,
Yes: as you stop down, the image circle gets bigger. Most image circles are given at f/16 but some are more conservative than others.
How does a drawing tell you you'll need a centre filter? So much depends on lens design, subject, personal preference. I've used 90mm on 6x17cm without a centre filter and 35mm on 6x9 without a centre filter (though I have the filter in question) but I have to admit I've never used anything wider than 90mm on 6x12.
Cheers,
R.
Yes: as you stop down, the image circle gets bigger. Most image circles are given at f/16 but some are more conservative than others.
How does a drawing tell you you'll need a centre filter? So much depends on lens design, subject, personal preference. I've used 90mm on 6x17cm without a centre filter and 35mm on 6x9 without a centre filter (though I have the filter in question) but I have to admit I've never used anything wider than 90mm on 6x12.
Cheers,
R.
venchka
Veteran
The final answer will probably come from the folks at the Large Format Photography Forum. Those people own and use just about everything you could imagine and a few things you can't imagine.
6x12 is awfully close to 4x5. I didn't realize that. The film used also has a bearing on center filter use. Slide film may need a filter while B&W may not.
Most large format lens image circles are quoted at f/22. The circle may be larger but the makers state full image quality at f/22.
If the 65mm lens doesn't work for you, there are several good 75mm lenses on the market. A 90mm lens will work without a center filter.
Good luck!
6x12 is awfully close to 4x5. I didn't realize that. The film used also has a bearing on center filter use. Slide film may need a filter while B&W may not.
Most large format lens image circles are quoted at f/22. The circle may be larger but the makers state full image quality at f/22.
If the 65mm lens doesn't work for you, there are several good 75mm lenses on the market. A 90mm lens will work without a center filter.
Good luck!
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HenningW
Well-known
I use a 6x12 back on Cambo Wides with 35 and 65 Grandagons and 47 SA-XL, all with centre filters most of the time. You might get away without one on the 65 if you're shooting a wide latitude film and don't mind noticeable vignetting, but mostly you're going to want one.
Henning
Matus
Well-known
The light fall-off somewhat depends on the lens too. Physics say that it goes with the cos(a)^4 where 'a' is the angle of the light entering the lens (or hitting the film plne). I have heard that Rodenstock Grandagon Apo/N (and maybe also the Nikkor SW) lenses use some different design what decreases the light fall-off to cos(a)^3.
I use Grandagon N 75/4.5 with my 4x5 and while I do notice the light fall-off with slide film, it is on the level of acceptable for me. Still - have have to use this lens more to get the conclusion.
I use Grandagon N 75/4.5 with my 4x5 and while I do notice the light fall-off with slide film, it is on the level of acceptable for me. Still - have have to use this lens more to get the conclusion.