Sharpness of Sheet Film vs Roll Film

[Jorge Gasteazoro]

8x10



MF

[J. P. Mose]

"The major, if not singular, quality which sheet film brings to the party is a remarkable ability to capture exquisitely fine detail. One often hears law enforcement people on the news lament the poor quality of digital surveillance pictures (which can’t be clearly enlarged) in bank robberies. "

Maybe why law enforcement still uses film, along with the fact that film can't be altered to change the facts.

[Dan Fromm]

Folks, reciting textbook results is alwaysamusing but in this case reports on shootouts would be more informative. So is posting images of different subjects shot at unspecified apertures with unspecified lenses on unspecified emulsions, but same/same/comparable/same would be more informative.

Since the original poster asked for a comparison of sheet film and roll film, has anyone here shot the same subject with the same lens with nominally the same emulsion at the same aperture on sheet film and on roll film? If so, please tell us how the results differed.

The thread then drifted to a series of rants about whether lenses made to cover LF, whatever that means, are sharper than lenses made to cover just 35 mm still. I reported one carefully done comparison (same subject, same emulsion, same apertures, same magnifications) done with roughly comparable lenses, in which the LF lens won. Can anyone else report similar shootouts?

Let's have more light, less heat, and fewer irrelevancies.

Cheers,

Dan

[Ralph]

Dan, I agree that flatbed scans aren't going to show very much. The only real test would be scanning a 35mm slide in a standard 4000dpi film scanner and cutting out a 24x36 piece from a large format transparency and scanning it in the same scanner. I don't have the capability to do that and even if I did I'm sure someone would take issue with the setup, film, or lens I used.

But your claim is still surprising to me, because while 35mm and MF lenses routinely resolve 90+ lp/mm (Christopher Perez's Mamiya 80mm resolved 120) I've never seen tests showing that LF lenses resolve more than 70 or 80. Christopher tested dozens of LF lenses, IIRC, and maybe he only tested mediocre lenses but few tested above 60 and only one or two resolved above 70).

http://www.hevanet.com/cperez/testing.html

It is so well-known that smaller format lenses almost always outresolve larger format lenses that it usually goes without saying, but if you're right and common wisdom is wrong -- if you can show proof of what you're saying -- I think it would really shake up a lot of DSLR/35 and MF discussion forums! (I'm kind of hoping I'm the one who's wrong, because if I can find a lens that "covers" 8x10 and resolves 80+ lp/mm on film, I'll have to figure out a way to buy it. . . : )

[John_4185]

Thank you for the pics, Jorge. Dan Fromm, I feel your pain and appreciate your skepticism regarding adequate performance over abstract metrics and assumptions regarding the Latest, Greatest (and most expensive).

Scanners are so problematic. I have a cheap Epson 3200 and don't plan to upgrade unless it breaks (and it is behaving badly.) It seems to suffice for web work.

FWIW, another data point (or not) see this: elearning.winona.edu/staff_o/jjs/f/

[Stan. Laurenson-Batten]

John.
I think it relevant to your question and to the KISS principle.

When I took up LF it was suggested that to obtain and maintain the correct overall film plane the surface of the dark slide should be double-sided taped. A method I have used at times, but which I am not fully convinced as to its merits. For me it just gives that little extra confidence in the end product.

[Christopher Perez]

I'm happy that people have pulled reality back into this conversation. So I'll refrain from replying regarding the validity of USAF test charts vs MTF vs aerial USAF chart inspections through the lens through an eyepiece. :-)

There was a question if someone had compared MF/LF film resolutions. I have. I see no difference between the native resolution of the various format's film. I have not checked 35mm film resolution. But I assume (and this might be dangerous, particularly around trollops wielding loupes :-) that 35mm film resolution is no different than MF or LF film.

[Jorge Gasteazoro]

The point I was trying to make was that I dont use a very rigourous technique. I focus on the ground glass, no loupe, and if it looks good in the GG it will be good enough for contact printing, even so the negative is very sharp, I cant see how transparency film would be any different, which leads me to beleive perhaps there was a problem with the transparency.

Having said that, I do have all the information about the lenses, aperture and exposure to take both images, but this is useless information, the end result we are looking for is two sharp images to compare.

[Dan Fromm]

Ralph commented, with sensible skepticism, "But your claim is still surprising to me, because while 35mm and MF lenses routinely resolve 90+ lp/mm (Christopher Perez's Mamiya 80mm resolved 120) I've never seen tests showing that LF lenses resolve more than 70 or 80. "

Ralph, you're right to be skeptical. Also a little wrong, I fear.

I picked the 200/4 MicroNikkor AIS precisely because it is not that great a lens. Modern Photography published a test of the AI version (same optics) in their 5/81 issue. At 1:49, the best resolution measured was at f/11, 49 lpmm center @ 49% contrast, 44 lpmm edge @ 29% contrast. It doesn't really cover 35 mm at infinity that well. Nor, in my experience, close up.

Many, not all, lenses for 35 mm that MP tested around the same time did much better than the 200/4 MicroNikkor. I still use my old 200 MicroNikkor. It is good enough, very useful, and a lot easier to use on a Nikon than the GRII.

Now, I regard the 55/2.8 MicroNikkor AI/AIS as a great lens. But the best MP got for it, test published 11/80, at 1:49 was 78/55 resolution 58/55 contrast at f/5.6; at 1:2, 64/54 resolution, contrast not reported, at f/5.6 and f/8. Not quite the 90+ that you believe in.

Ages ago MP published a piece on whether 100+ lp/mm was attainable with 35 mm still. Their answer was a carefully qualified yes. Getting that much resolution required a very good lens, high resolution film, more steadiness than most of us ever manage, and very careful focusing. As a practical matter, resolution that high is a fantasy, especially with ISO 100 and faster color films.

I picked the 210/9 GRII because it is the best lens I have at that focal length and because it is pretty good too. And since I did the shootout with a Nikon, there were no coverage problems with it.

We should all remember that most blanket statements are false, at least at the edges. There are great LF lenses, mediocre and worse ones for 35 mm still. I don't know how great lenses for LF compare with great lenses for 35 mm still. I've never asked that question m'self. But I know at first hand that pretty damn good lenses for LF can beat middling lenses for smaller formats.

Cheers,

[John_4185]

[b]dan[/b[ We should all remember that most blanket statements are false...

Including that one.

elearning.winona.edu/staff_o/jjs/f/rez1.html