300mm lens which is sharpest aperture

[robc]

if you have a 300mm lens, which aperture do you consider to be its absolute sharpest ignoring dof.

[John Kasaian]

My 300mm Dagor practically sings at f/64 while my 300mm Nikkor M does amazing stuff at f/16

[Walter Calahan]

What does it matter? Sharpness is only a tool for translating one's vision to paper.

[Brian Ellis]

I have no idea. Do people actually go out and make 7 or 8 identical photographs, process the negatives, and then compare them to see which is "sharpest?" I've never tried that but just from looking at my prints I've never noticed any difference in "sharpness" that I could attribute solely to the aperture used. There are so many variables that enter into the perception of "sharpness" that without an optical bench or something like that I would have thought it would be pretty difficult to tell which aperture was "sharpest," at least not just from examining prints.

I also wouldn't have expected all lenses of the same focal length to be "sharpest" at the same aperture but then I don't know very much about lens design. So I guess I'll learn something from the results of this poll. I do think that if someone says they know their 300mm lens is "sharpest" at a particular aperture it would be nice if they could briefly explain how they made that determination. I don't mean a lengthy scientific paper, just something like whether it was from examining identical negatives with a loupe, looking at prints, whatever.

[Christopher Perez]

As a matter of engineering interest, I have taken various lenses out and shot them side by side at varying apertures. It's very instructional. Once the lessons are learned, the engineering portion of my brain was able to settle down and let the artistic half of my brain take over.

Your conclusions match mine. I tend to think of it this way: It takes a really aweful lens to see any difference in real world resolution.

I know this to be the case when I can take an ancient 183mm Bausch and Lomb f/18 Protar series V (coated) and show that it can make prints as sharp and contrasty as my modern multi-coated super wonder Nikon 200M or Schneider Symmar-S/MC at f/22. Still, I prefer the modern lenses in day to day use.

The sharpest lens I own is a tripod.

...Do people actually go out and make 7 or 8 identical photographs, process the negatives, and then compare them to see which is "sharpest?" I've never tried that but just from looking at my prints I've never noticed any difference in "sharpness" that I could attribute solely to the aperture used...

[Eric Rose]

I'm with Brian on this. I use whatever f stop gives me the dof I want and/or shutter speed. Make art, not tests.

[Capocheny]

Rob,

Can't say that I've ever stopped to "actually" determine which f-stop is the sharpest for my lenses... but then, for the majority of my shots, I usually stop down to at least f16 and smaller anyway.

Cheers

[Dan Fromm]

Brian, thanks to accidents and bad judgement I have too many lenses, so I've been systematically weeding 'em out. Not to rank them, just to decide which ones not to use. And where there are dupes -- two 150/9 Apo Ronars, at one time many 35/4.5 Tominons, for example -- to see whether there's any difference between 'em. I don't shoot formal lens tests, although I've done that with some fine macro lenses, but acceptance tests. Not at all distance/aperture combinations, but more or less as I expect to use them.

As Chris Perez keeps on reporting, there are indeed differences between lenses AND most decent lenses in good order are better than merely fit to use. Its really hard to justify further chasing after mythical wonderglass. What I have and shoot is for the most part better than I am. I'll get more return from sharpening up my technique than from mindlessly buying lenses and so, I fear, will most of us.

So I find discussions of which lens is the absolutely best of all stupid wastes of time.

Similarly for this and parallel threads. We all use our tools as is appropriate, not to maximize an irrelevant figure of merit. What's appropriate depends on the subject and the final print we have in mind when shooting. Yeah, more resolution at a useful contrast is nice to have, but on the whole MTFs are another "so what?"

Cheers,

Dan

[Brian Ellis]

Hi Dan - I'm sorry if my message came across as being critical of lens tests or discussions of lens sharpness. I didn't intend that and I thought my statement about learning something made it clear that the topic interests me. I just haven't done any tests myself but I'm certainly happy to learn from people who have. As you say, there are definitely bigger ways to waste one's time in this forum than talking about lens sharpness (and over the years I think I've participated in most of them).

[sanking]

if you have a 300mm lens, which aperture do you consider to be its absolute sharpest ignoring dof.

This varies greatly according to lens design. However, f you ignore completely DOF the sharpest aperture of most modern 300 mm lenses used for LF photography will be one to two stops from maximum aperture, and the difference between various brands is not likely to be of any practical consequence for most applications. Of course, you can only ignore DOF if your subject is a plane subject at some finite distance from the lens.

As you stop down a lens the negative impact of certain lens aberrations are reduced, but the effects of diffraction increase. With most modern lenses, ignoring DOF, the optimum aperture, as noted above, is one or two stops from maximum aperture.

Sandy King