Depth of field. Large format compared to 35mm.

John Cook,

 

I'm not sure where you got your inforamtion....but LF lenses are NOT as sharp as there 35mm counterparts. This is well known.

Dave Luttmann wrote "I'm not sure where you got your inforamtion....but LF lenses are NOT as sharp as there 35mm counterparts. This is well known."

 

Dave, it is indeed the case that SOME lenses made for 35 mm are sharper than SOME lenses made for large format. But this is not true of all.

 

For example, I have a 210/9 Konica Hexanon GRII. This is a lens made for a vertical copy camera. Some users claim it covers 8x10. I wouldn't know about that, since I usually shoot mine on a 2x3 Graphic.

 

I also have a 200/4 MicroNikkor AI that I shoot on my Nikons. It is an ok lens but not, in my opinion, outstanding. My shorter MicroNikkors are better. NB, this is the old manual focus 200/4 MicroNikkor, not the current AF one; by all accounts the current one is outstanding.

 

I've shot the two lenses against each other at 1:2, the MicroNikkor's highest magnification on its own mount, and at about 30 feet. I shot them with the same Nikon, the same rolls of film, and at f/11, f/16, and f/22. On copy stand with flash illumination close-up, on tripod with cable release and self-timer at 30'. The GRII shot better than the MicroNikkor magnification for magnification, aperture for aperture. My 200 MicroNikkor is the second one I've had, shoots as well as the first, so I don't think I have a bad 'un.

 

End of discussion. Some LF lenses ARE better than the comparable lens for 35 mm, now please shut up.

Dan; our big process process camera has a 890mm F14 Ronar; used to cover a 24x36" negative. I really want to get another 308mm ish F2.5 aero Ektar again; I had one in the 1970's and sold it. <BR><BR>Gerald; the shallower DOF is often used with LF work to purposely isolate an object. Also LF has a smoother tonal appearance; since it is enlarged less when making large prints.<BR><BR>

Kelly, now that you mention it, I've long been fascinated by the 12"/2.5 AeroEktar. Too huge for my tiny little cameras of nothing at all, though, so I make do with a 12"/4 Taylor Hobson Telephoto. What did you hang yours on, and how well did it shoot?

 

Interesting factoid about Apo Ronars, as long as we're drifing off topic. Somewhere in Rodenstock's propaganda about Apo Ronars is an assertion to the effect that for use at long distances an AR is better than any telephoto.

 

Cheers,

 

Dan

Dan,

 

Your mouth is big, but your knowledge isn't. On average, resolving power on an absolute basis is greater for the 35mm format than for LF. Yes some lenses are better than others. An extensive writeup was done by Ctein on this very topic. I consider him a fairly reliable source. The same was brought up by Norman Mcgrath in a recent VC article on the differences between film and digital for architectural photography.

 

So you see, your uninformed comment is NOT the "end of discussion". And as you don't seem to have any power over replies here, kindly keep your "shut up" comments to yourself and go do some background work before you spout off the mouth about something you seem to have an opinion about, but little fact to back it up.

 

Good Day!

Dave; Barry Stein is a physics chap; not an Engineer. He got involved in Photography and optics long after many of us have used the same lens on many formats. In real optical engineering one deals with resolution on film; a sensor with a some design margin; not a best case number. Lenses dont know what piece of film is behind them. Most optical chaps think is resolution in arc angle; and less so lines/mm. A sweeping statement that 35mm is better than LF or vice versa is narrow minded. A 100mm lens could be used on a 8mm movie camera; a 16mm movie camera; a 35mm movie camera; a 35mm still camera; a 6x9cm Kodak folder; a Medalist; a 4x5 view camera. The sharpeness critera are different for each; the ease of focusing accuracy is different for each. <BR><BR>It is real easy for a 50mm lens to resolve 50 line pairs/mm; than a 100mm lens; than a 200mm lens; than a 400mm lens. It has nothing to do with format; but arc angle; and chromatic abberation too. A 50mm lens ONLY HAS TO RESOLVE ON HALF THE ARC ANGLE OF THE 100MM LENS; to hit 50 line pairs/mm on film. This is pure 10th grade geometry. Shorter lenses are generally easier to correct for chromatic errors; with "regular optical glass". The easy of making a hitting a home run 70 line pairs/mm with a 40mm lens are RADICALLY easier that hitting 70 line pairs/mm with a 400mm lens. A junk Canonet rangefinder for 20 bucks will do this; a many thousand dollar 400mm probably will not. It doesnt matter whether it is a 400mm lens for 35mm; MF; LF; or a spy camera; you are against the design wall with 400mm; in the done 1/2 century ago with the 40mm design. <BR><BR> it is less of a format issue; than a focal length issue. Many times beyond 100 to 200mm; practical "lines per mm" values due tank. In this region more expensive glass can help<BR><BR>

Dave; one big factor in LF is the focus position tolerance is poor. With a military aerial camera; or a process camera; one often uses a vacuum back. With my 35 MP 4x5 scan back; one can fine adjust the focus; and drop the focus error alot. One is focusing with the sensor.

Kelly,

 

Your response basically says that because of focal length, 35mm lenses are inherently sharper. I didn't give the reason why....but the final result is the same. The fact that they resolve more could be attributed to a million things....however, the end result is the same.....they resolve more.

 

In various tests, peak resolution for MF 6x7 rarely came up to 2/3 that of 35mm optics.....large format didn't even fare that well. I undertsand that it doesn't have to as magnification is much less for the larger formats. But mainly, I don't appreciate being told to "shut up" by someone who clearly lacks a basic understanding of the topic

 

 

By the way, you spell his name "Ctein"

Dave; Barry Stein use to write for the elecronics magazines; I am never one to follow "I'll change my name today" crowd. It is Barry's pseudonym when writting science; far out fantasy; I guess now photo stuff. Barry was been involved in some far out stuff; blue shift. Cal tech Physics guy; he was at the 60th World Science Fiction Conference in 2002 in San Jose. Here I am an engineer. When a person quotes Barry's experiments saying an XYZ enlarging lens is sharpest wide open; I wonder about the microfilm camera I worked on; that used the same lens; where we had to stop it down to live with real world film and check tolerances. This is the concept of engineering; having a design margin; to deal with real life things like film; and not perfect glass plates. It is easy to get higher numbers with a best case test of one. In the real world negatives move abit; this is the typical Engineer versus Physics chap tussle. Who gets to fix the mess in production? Who get flown oversea on a tiger team to change the design? Was a worse case tolerance done?

Dave another analogies:<BR><BR>Do heavier cars get worse gas mileage?<BR><BR>Do heavier people eat more food?<BR><BR>Do Larger format cameras weight more?<BR><BR>Is a taller player a better basketball player?<BR><BR>Do bigger dogs bark louder? :)<BR><BR>With cars; generally heavier cars get less gas mileage. BUT if one says they always do; then folks will pull out many many valid exceptions; and get excited!

Dave, let's see now. You made a flat assertion. I provided a counter example. Your assertion is wrong. Still end of discussion. Yelling at me won't change that.

 

Cheers,

 

Dan

And Dan,

 

Because a smoker lived to be 100, smoking must on average be good for you. That's your logic. The discussion is ended by me because one example does not a rule make. On the whole, on a per mm basis, LF has lower resolving power because of nearly every part of the imaging chain....ie: the lenses, film flatness, focus issues, etc, etc. Now for every example you come up with, I'll find 10 that show the opposite. But feel free to point me to all the multitudea of tests that show me to be mistaken. I won't hold me breath.

 

Oh, and the only reason you "got yelled at" was your extreme rudeness.

Dave: All A are B.

 

Me: Here's an A that isn't a B. Therefore not all A are B.

 

End of discussion, again.

 

The health benefits of smoking tobacco or anything else aren't involved. If you had asserted that no smokers attain the age of 60, then any smoker who survived longer would falsify your assertion. That some smokers survive longer than that, as in your example, has nothing to do with whether smoking reduces life expectancy.

 

What you did assert is "LF lenses are NOT as sharp as there 35mm counterparts. This is well known." And you didn't allow exceptions.

 

I've measured, and I own an exception. That's enough to falsify your assertion. As I keep saying, end of discussion.

 

The only intellectually respectable response from you is to qualify your assertion. Bringing in the entire imaging chain is an evasion. Bringing in averages is an evasion. Misrepresenting what I said is dishonest.

 

Your other out is to demonstrate that I erred and that my 210/9 GRII is not a sharper contrastier lens, under my test conditions, than my 200/4 MicroNikkor AI. I could have erred, I certainly have before, but in this instance I don't think I did.