Best Aperture

[pico]

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From a relaxed Sunday reviewing negatives from full-frame 35mm, as well as 6x9cm and 4x5" I have concluded that the best aperture for the focused image regardless of format is 6mm diameter (my favorite) to 12mm in diameter. It is all about  diffraction. For FF 35mm, that comes to about F/5.6, regardless of focal length.

 

Rebuttals?

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[michaelwj]

I don't think you made an argument, so there is really nothing to rebut.

You like a 6mm aperture. I too like a 35mm FF lens at 5.6. It has a nice balance of sharp and unsharp while still being recognisable.

Something about it all because of diffraction? I'm not sure where this came from? Are you implying that once we get less than 6mm we are succumbing to diffraction effects? How about the roll of magnification?

I don't follow. Maybe I missed something? I usually do.

 

By the way, I do not mean to offend, rather prod for more information on your logic.

 

Michael

[pico]

I don't think you made an argument, so there is really nothing to rebut.

You like a 6mm aperture. I too like a 35mm FF lens at 5.6. It has a nice balance of sharp and unsharp while still being recognisable.

Something about it all because of diffraction? I'm not sure where this came from? Are you implying that once we get less than 6mm we are succumbing to diffraction effects? How about the roll of magnification?

I don't follow. Maybe I missed something? I usually do.

 

By the way, I do not mean to offend, rather prod for more information on your logic.

 

Michael

 

I am saying that the physical size of the aperture, not the f-stop given on the lens, is the thing to consider when minimizing unsharpness due to diffraction. The best aperture falls between 6 and 12mm: the difference of 6 to 12 depends upon the design of the lens. Degree of enlargement at a nominal-normal viewing distance makes up for the format size: a larger sensor/film format requires less enlargement so that diffraction is minimized if not eliminated.

[pippy]

You could well be correct, pico.

Certainly I've read in quite a few places that the optimum shooting aperture for most lenses on a FF digi-cam is around f5.6 to f8 so your observations would pretty much concur with these reports.

 

For me (and the sort of snaps I take) the primary consideration for shooting is almost always 'what is the required D-o-F?'.

 

As it happens (as a very broad generalisation having reviewed a few dozen pics I've posted hereabouts) I usually seem to end up shooting in the f8 to f11 range.

I can't say that I've noticed any lack of IQ in these 'real world' images but at the same time I know through my studio work with DSLRs to avoid going beyond f11 if at all possible. Sometimes I need f22 and there is a distinct balancing-act between trying to obtain "required" image-sharpness through D-o-F and "possible" image-sharpness through small aperture.

 

Pip.

[Paul J]

I don't stress too much about these things. I shoot what works for the image and use what aperture is needed.

[ramarren]

I don't stress too much about these things. I shoot what works for the image and use what aperture is needed.

 

 

+1 

 

The old adage "f/8 and Be There" seemed to be about a 50mm lens and gives you ~6mm lens opening. So f/5.6 with a 35mm ... sure. 

 

The other old adage is "two stops down from wide open for best quality" is another useful rule of thumb for getting good lens performance, this one not tied to specific lens opening diameter. 

 

Whatever works for you is best. 

[pico]

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The other old adage is "two stops down from wide open for best quality" is another useful rule of thumb for getting good lens performance, this one not tied to specific lens opening diameter. 

 

For most of their lenses, large format photographers would disagree. Exceptions being reproduction lenses.

[spydrxx]

Most of the 35mm lenses I've tested over the years tended to show best (most overall pleasing to me) resolution, centrally and across the field, in the f/5.6-8 area, although several Leica and Canon (LTM) came in about f/2.8-4. I generally shoot at f/5.6 most of the time anyway, but do keep a laundry list for each lens currently owned in my bag showing points of optimal resolution - useful if I'm using a lens I haven't used in a couple of years.

[jaapv]

I find that one of the special things about Leica is that one gets great results at any aperture, leaving the photographer free to use the amount of DOF creatively. Shooting for maximum resolution is, imo, rather self-defeating, except in some applications like landscape from a tripod.

[ramarren]

For most of their lenses, large format photographers would disagree. Exceptions being reproduction lenses.

 

This may well be, but I thought we were discussing small-format, hand held cameras, specifically Leicas, on this forum?

[earleygallery]

I use the aperture I want or need to use, I don't stress about what are relatively minor differences in quality, but where limited DOF isn't required and the exposure allows for it I'll generally use f5.6 or f8 on any given lens. 

[pico]

This may well be, but I thought we were discussing small-format, hand held cameras, specifically Leicas, on this forum?

 

The statement was inclusive of 35mm format, but stated a universal which includes LF, and that makes it most interesting. But I'll give you an extra point for dodging the subject.

.

[pico]

Most of the 35mm lenses I've tested over the years tended to show best (most overall pleasing to me) resolution, centrally and across the field, in the f/5.6-8 area, although several Leica and Canon (LTM) came in about f/2.8-4. I generally shoot at f/5.6 most of the time anyway,  [...]

 

If you were to measure the diameter of those favorite apertures, they would probably fall into the range I stated.

[Herr Barnack]

Should we revise the old adage mentioned to "6mm and be there?"  I think maybe so.  It will confuse everyone who is not privy to this thread! 

[pico]

Should we revise the old adage mentioned to "6mm and be there?"  I think maybe so.  It will confuse everyone who is not privy to this thread! 

 

To be true to the era of the expression we should include the distance, flashbulb number and diameter of the reflector. I feel almost guilty of still having a lot of flashbulbs and firing hardware.

 

One my favorites, posted earlier, a dedicated battery-less flash for early Leica. The power source is a magneto! I have this unit but not the the that Leica fits it. Can someone tell me what Leica model is shown here? TIA!

 

[lct]

Look likes Brigitte Bardot's Leica IIIf

BB's Leica IIIf.jpg

 

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[michaelwj]

I am saying that the physical size of the aperture, not the f-stop given on the lens, is the thing to consider when minimizing unsharpness due to diffraction. The best aperture falls between 6 and 12mm: the difference of 6 to 12 depends upon the design of the lens. Degree of enlargement at a nominal-normal viewing distance makes up for the format size: a larger sensor/film format requires less enlargement so that diffraction is minimized if not eliminated.

 

I am saying that you are incorrect - but that for your use of your equipment it may very well be correct, but not in general correct.

 

By fixing the physical size of the aperture to 6-12mm you are implying that the optimum aperture for a 600mm lens is between f/100 and f/50; so optimum sharpness is never reached on a modern FF camera with a long lens? Or alternatively that my iPhone never achieves optimal sharpness as the whole camera is less than 6mm diameter?

 

I would also love to hear how the lens design impacts the physical size of the aperture? Which lenses were better at 12mm at which at 6mm? I would hazard a guess that the longer focal lengths were better at 12mm, and the shorter at 6mm - regardless of format. Of course, I'm happy to be proven wrong.

If you have time can you see which lenses were better at which aperture size? I think it might be enlightening in many ways. Over and above focal length I feel like it may be impacted by where the iris is in the lens (front - back) and the angle that the light passes through the iris (which in general will be related to focal length but also lens design).

 

Cheers,

Michael

 

p.s. I only use two lenses on one format, so don't have the variety to do the test myself. I also place 'maximum sharpness' a long way down my list on what I consider when taking a photo, so this is purely academic for me - and very interesting

[ramarren]

The statement was inclusive of 35mm format, but stated a universal which includes LF, and that makes it most interesting. But I'll give you an extra point for dodging the subject.

.

 

 

Then I completely disagree with you. 

But thanks for the point. 

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[jaapv]

Look likes Brigitte Bardot's Leica IIIf

BB's Leica IIIf.jpg

 

350px-IIIf-dwg.jpg

What  IIIf ??? :D

[jmahto]

From a relaxed Sunday reviewing negatives from full-frame 35mm, as well as 6x9cm and 4x5" I have concluded that the best aperture for the focused image regardless of format is 6mm diameter (my favorite) to 12mm in diameter. It is all about  diffraction. For FF 35mm, that comes to about F/5.6, regardless of focal length.

 

Rebuttals?

.

Hmmm.... I think the diameter causing diffraction related softness is a "limit" and not optimal. Wider diameter is always theoretically better. Isn't it?

 

I agree that from a practical point of view, one may choose around f/5.6 for FF since wider aperture will have softer corners. But this is lens design issue and not a theoretical optimum.