I just mounted an in barrel 300mm f/9 Apo-Ronar for use with my 4x5 camera. My goal was to achieve infinite depth of field at 1:1 or greater. I used this lens because the iris on this lens stopped down to f/260. The result was a completely fuzzy image. Is this normal for these lenses? If so, are there any other lenses anyone knows of I can use to achieve my goal? BTW, the image was great wide open.
At F/260 I'm not surprised things got fuzzy. My math maybe off but you can't get more then 6 or 7 lp/mm at F/260.
Isn't it a simple case of diffraction? f260 on 4x5 is equivalent to f64 on 35mm and f128 on 6x6. It's way small. I think the small aperture was meant for repro work using 16x20 or larger films (or whatever on the other side of the lens).
It's actually even worse than that. f/260 at 1:1 macro magnification becomes an effective f/520. That is essentially pinhole photography and you are definitely diffraction limited. You will have a lot of depth of field but resolution will be pretty poor. So everything will be equally in focus (or out of focus, depending on your point of view). Macro work is hard for exactly that reason. Thinking of compositions that will reduce your DOF demands is the best way to proceed here.
In some ways, LF is particularly hard. Keep in mind that 1:1 in 35 mm is an approximately 1 square inch area (a small flower, for e.g.). The same 1:1 in 4X5 is a 20 square inch area (a small bed of flowers) which most of us do not intuitively think of as macro work - we tend to think of macro work as being very small things. So, if you try to do the usual kind of macro work (a small flower), you are effectively looking at something like 3X or so magnification and your effective aperture is becoming very problematic. When doing macro work in LF, you really need to rethink your ideas of what macro compositions are. But when it works, the smooth tonalities are to die for.
Cheers, DJ
Hi there,
You could try a 75 - 105mm enlarger lens reversed and/or a precision drilled waterhouse stop. Any adjustable iris has a very jagged edge when stopped down making the diffaction problem worse.
You could get in touch with Panaflex for one of their infinite depth of field lenses but they will not sell them (and they are patented)
Good luck with the impossible.
You are deeply into diffraction. That lens was made to be used at f16 to 22 only.
Bob:
I'm glad you checked in. Since this lens should be used at f16 to f22, why have markings all the way to f260? Is there some historical significance? Process Camera application that used such small stops?
Thanks.
Tom,
If you had bought a lens that only had markings for optimal aperture then people would want to know why there was so much movement before and beyond the optimal settings.
I have three process lenses, all F9, different sizes, and like Bob says, I use them all around F22 on average, although my Apo Artar seems to work great at F32. Still, F32 is waaay far off from f260. Try F16 to F32, see how it works
joe
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Not to minimize the importance of Mr. Moore's original question, but ...
I noticed Hiro's comments, for example. Can Hiro or anyone tell me why repro lenses often stop down so far - to f128/f260, for example? Is it simply for the fact that when shooting line-copy onto 16x20 film, normal diffraction at these pinhole apertures doesn't become an issue? I would think that on a litho camera one would shoot at the "best" aperture all the time. With lighting constant and subject (line copy, for example) motionless - what in the world would you need to stop down so far for? I am puzzled!!! Did this allow lithographers to imagine they had more "control" or what?
Thanks!
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