Maximum sharpness

[Jim Jones]

As EVH says, although I didn't state it I made the assumption that the shooter 'would' use the same equivalent focal length on the smaller format. Lets say he was using a 150mm lens on a 4x5, I wouldn't expect him to use a 150mm on a 35mm but if he used a 50mm lens stopped down to 16 you'd have a sharper print than a 150mm lens on a 4x5 stopped down to the same F stop.


I believe it has something to do with the circle of confusion, although I understand the principal I get confused when I try to explain it :-).

Diffraction can limit the sharpness of a good 50mm lens stopped down to f/16 on a 35mm camera. One can see the effect of stopping down too much by observing the image formed from 35mm film in an enlarger. Fine grain starts to get slightly fuzzy at about f/8. A big enlargement printed at f/16 will likely appear less sharp than at f/8. Normal focal lengths on 8x10 were often stopped down to f/64 with little sharpness loss due to diffraction. The choice of optimum aperture depends on format size, subject matter and distance, required DOF, viewer's preference, subject movement, print size, and too many other factors to discuss at length here.

[CP Goerz]

'Diffraction can limit the sharpness of a good 50mm lens stopped down to f/16 on a 35mm camera. '


F16 was a bad choice on my part to use but I wanted a 'realistic' choice of aperture that can be considered 'equivalent/possible on both 35mm and 4x5.


If we take the same shot at F5.6 with a 4x5 and at F5.6 on a 35mm the 35mm will appear sharper, it will also be sharper at F8 and 11. Chances are that even at F32/45/64 the very center of the image shot on 4x5 in this particular instance won't match the 35mm at F8/11.

[Lenny Eiger]

I have been following this conversation and I find I must protest. (Or respectfully disagree.) There are many reasons why a shot inside a garage like that, with awful, low lighting would be slightly unsharp. Diffraction doesn't come to mind.

I can appreciate that diffraction exists, but its effect is minimal, even less if scanning and digital printing is involved. There have been many threads to this effect, don't take my work for it, most of the experienced folks have agreed that diffraction is a very small factor, especially when shooting outside vs doing tabletop in the studio.

I have a Mamiya 7 II and the lenses are amazing. They are much sharper than my Rodenstocks' I have for 4x5 and 8x10. However, their depth of field is limited, to the point where I don't feel I can use it. The garage shot in question needs depth of field, and quiet. It is a long exposure, if a truck goes by, even upstairs, the building could have enough vibration to make a mess.

A light bit of swing could help the focus given the viewer will likely be looking at the wall, and whether or not it holds its sharpness along the horizontal. But there is nothing one can do to do that and help the floor to ceiling all hold, especially in combination, except close down the aperture.

Now maybe others have a different experience, but I have tested my lenses at f16 thru to f45 and I see no real difference in overall quality. I did notice a slight falloff of sharpness going to f64, but the difference in the other stops was so minimal, that I am sure does not survive the printing process. As a result I shoot mostly at f45.

There are many adages in photography. "Expose for the shadows, develop for the highlights" is a favorite of mine. However, when it comes to this "word on the street" that one can "only go two stops down from wide open", I think its all wet.

Don't trust me. Grab an extra holder or two, and maybe a watch with a second hand, spend the extra $5 or whatever it is, and do the test for yourself. Expose at a few different apertures and see what your own lens can (or can't) do. My guess is that you won't worry too much about diffraction when you are done.

Lenny

[Paul Fitzgerald]

"My question is: could I have done anything else to maximize sharpness?"

The only other option is to move farther back and use a longer lens to reframe the photo.
Moving farther back would change the 'focus spread' in the scene making it easier to get the DOF needed.
(150mm 15' near + 75' far = 5X)(210mm 20' near + 80' far = 4X) (300mm 30' near + 90' far = 3X)

If you look at most 'everything in focus' photos, NOTHING is closer than 20' to the camera for a reason.

Have fun with it.

[Doremus Scudder]

I'm with Lenny on this one. I'd much rather have the slight overall degradation due to diffraction than out-of-focus areas in scenes like this. Shooting at f 45 (on 4x5) yields almost no discernible diffraction degradation until print size reaches 16x20 or so. f 64 gives really nice 8x10s and I use that aperture a lot for still-lifes and close-ups that I don't want to print any larger anyway.

And, why not bracket DoF in a case like this? I do that all the time; take a shot that's maybe on the edge of having out-of-focus areas and then another stopped down another stop. I usually end up printing the latter one.

Best,

Doremus

[CP Goerz]

miesnert ...What did you actually shoot this image at F stop-wise?

[Andrew O'Neill]

miesnert, the example you provided looks pretty sharp overall on my monitor, to my eyes.

[C. D. Keth]

The only other option is to move farther back and use a longer lens to reframe the photo.
Moving farther back would change the 'focus spread' in the scene making it easier to get the DOF needed.
(150mm 15' near + 75' far = 5X)(210mm 20' near + 80' far = 4X) (300mm 30' near + 90' far = 3X)

In all cases that you present, the total depth of field is 60 feet. That doesn't seem like a very effective way of increasing total depth of field.

[Paul Fitzgerald]

"In all cases that you present, the total depth of field is 60 feet. That doesn't seem like a very effective way of increasing total depth of field. "

Actually it's decreasing the need for DOF, taken to extremes it's called 'telephoto compression'.
The 150mm needs f/24 for 15 - 75', f/16 for 20 - 80', or f/8 for 30 - 90'
OR
150mm at 15-75' = f/24
210mm at 20-80' = f/22
300mm at 30-90' = f/16

Moving back and/or changing the FL will change to perspective.
It's all an optical illusion.

[Brian Ellis]

. . . The rule of thumb is that all other things being equal, DOF depends on reproduction ratio.

I have to respectfully disagree. I was taught and I believe that DOF depends on three things and three things only - aperture, focal length, and distance from subject. Apparent sharpness of the print depends on reproduction ratio, depth of field, viewing distance, lighting, the viewer's visual acuity, etc..

At least that's my understanding. To me, equating depth of field with apparent sharpness of the print leads to confusion (and not the circular kind).