f64

[onnect17]

Peter, I think it makes perfect sense. The higher the sampling frequency (in this case scanning resolution) the more accurate you will be able to capture the shape and size of the grain. In fact, with regular developers (no stain) the image structure should be almost monotone, pretty much the gelatin plus the grain. At 6000 dpi a gray surface in grainy negative should show an histogram with a couple of bars instead of one in the middle.

The worst scan resolution should be the closest to the grain size and once you are over twice the grain size the sampling error becomes smaller and smaller (check Nyquist frequency in wikipedia). It also explains why so many love TMY more than TMX.

[onnect17]

I remember reading about optimal focus and f-stop in VC magazine a couple of years back. Here's the link to the two parts article.
http://www-unix.oit.umass.edu/~rbhome/technical.htm

[Sal Santamaura]

This thread and its controversies has been dormant for quite a while. Lenny (the OP) doesn't even post here any more. But, I've some information to add, so here goes for the archive.

Back in post #1, Lenny described how he tested by "pointing his camera out his front door and closing down to f/64." He wrote that he was perfectly satisfied with the resulting sharpness. Lenny first used a 300mm f/5.6 Nikkor W for the experiment. Later, seeking more coverage and possibly better performance, he obtained a 300mm f/5.6 Apo Sironar S. Comparing the two lenses, Lenny found them to be almost identical. Not wanting or needing them both, he offered the Nikkor for sale. I bought it.

Fast forward to last week. Lots of life got in the way since my Nikkor W purchase occurred. However, now having the time (and three 3004 Expert drums), I finally got around to comparing eight of my lenses, including that 300mm Nikkor W, using the "standard scene" in our back yard. That scene includes an Edmunds chart, Macbeth Color Checker, Kodak gray card and lots of natural elements like trees and shrubs, all about 50 feet distant from the camera.

Tested lenses were:

• 450mm f/8 CM Fujinon W
• 450mm f/12.5 Fujinon C
• 420mm f/8 Fujinon L
• 300mm f/9 Fujinon A (EBC multi-coated version)
• 300mm f/5.6 Fujinon W (single-coated version)
• 300mm f/5.6 Nikkor W
• 270mm f/9 G-Claron
• 250mm f/6.7 Fujinon W

Two exposures, incorporating significant rise and shift, thereby using much of the available image circles, were made with each lens; one at f/45 and another at f/64. These were the results at f/45.

Long lenses: the 450CM-W and 420 L were fairly sharp. The 450 C was slightly less sharp.

"Normal" lenses: the 300 A was moderately sharp (less so than the 450 CM-W/C). The Fuji 300 W was significantly sharper than the 300 A. The Nikkor 300 W was extraordinarily sharp.

"Wide" lenses: the 270 G-Claron was very sharp (performance between the 300 A and Fuji 300 W). The 250 W was moderately sharp (about like the 300 A).

At f/64, seven of these lenses suffered substantial sharpness deterioration compared to their performance at f/45, so much that I can see it looking at the negatives on a light box without magnification. One, however, became only slightly less sharp -- the 300mm f/5.6 Nikkor W. With that lens, the difference was so small it can't be seen without magnification. While the loupe reveals minimal blurring, I wouldn't hesitate to say that a 2X optical enlargement might be indistinguishable (in terms of sharpness) from a contact print of the others at f/64.

What I take away from this, beyond the usual sample variation caveats, is that one ought not question another photographer's results without seeing them in person. The difference at f/64 between a vaunted ("clinically sharp") 300mm Fujinon A and Lenny's 300mm Nikkor W is astounding.

[Peter De Smidt]

Good stuff, Sal. Thanks for posting!

[Drew Wiley]

I miss Lenny. But I never did agree with his opinions about lens sharpness. For one thing, he scans; for another, tends to print small. Then third, his method of
evaluation is hardly scientific; and fourth, having owned, used, and done big critical enlargements from many of these lenses myself, I know the relevant variables, and can only continue to disagree with much of the above. There must be some inherent flaw in his technique that he has overlooked. Otherwise, diffraction gets pretty apparent with ANY 8x10 lens compared to f/64. Contact printers don't tend to notice this, nor do those whose main problem is an unflat film plane. But it is there. Those of us who routinely carry Fuji A and C lenses know what utterly superb performers they are, even in smaller 4x5 applications demanding still greater enlargement. But diffraction is the great equalizer.

[Drew Wiley]

... and yes, I did notice that this is a digital thread. So more layers of potential variables that have nothing to do with lens performance itself. The bottleneck is more likely in the workflow.

[Sal Santamaura]

I miss Lenny. But I never did agree with his opinions about lens sharpness. For one thing, he scans; for another, tends to print small. Then third, his method of evaluation is hardly scientific; and fourth, having owned, used, and done big critical enlargements from many of these lenses myself, I know the relevant variables, and can only continue to disagree with much of the above...

Drew, did you actually read what I posted today? What might be "unscientific" about how I went about this comparison (Looking at the negatives on a light box, both with and without the aid of a loupe)? What variables might have inlfuenced the outcome? All my holders were purchased brand new after being selected from store stock by depth checking a much larger number than ultimately purchased; they're the pick of the litter. There were no substantive changes in temperature or humidity between when the film was loaded and exposures were made. The camera back was vertical -- no film sag.

...There must be some inherent flaw in his technique that he has overlooked. Otherwise, diffraction gets pretty apparent with ANY 8x10 lens compared to f/64...

Forget Lenny's "technique." There's no flaw in how I went about this experiment. As stated, with seven of the eight lenses, sharpness degradation at f/64 WAS readily apparent (compared to f/45) looking at negatives on a light box with the unaided eye. For the 300mm f/5.6 Nikkor W, it was not; a loupe was necessary to see the surprisingly small effect of diffraction with that exceptional lens.

...Those of us who routinely carry Fuji A and C lenses know what utterly superb performers they are, even in smaller 4x5 applications demanding still greater enlargement. But diffraction is the great equalizer.

I own EBC multicoated Fujinon A lenses in 180mm, 240mm, 300mm and 360mm focal lengths. In addition to the 8x10 test described in this thread, I also recently compared the 240mm A to a 240mm Germinar W, both at f/32 for 5x7 use. The Germinar was far, far sharper. At the same time, I compared the 300mm A to a 300mm f/9 Nikkor M, again at f/32. The Nikkor was far, far sharper. Again, all holders' depth confirmed as spot on, etc. Several months ago, I also compared the 360A on 4x5 to a Schneider 350mm f/11 Apo Tele Xenar Compact and 355mm Kern Dagor, all at f/22. In that case the Fujinon was sharpest, but I wonder whether it would have been had the competition included a 240mm Nikkor W. I don't own the latter lens, so can't say for sure. As for Fujinon C lenses, my post today indicates the 450mm version isn't bad, but doesn't match the sharpness of the other two 400mm+ optics I tested it against. I once had a 300C, but sold it, since it exhibited extremely low contrast. Finally, I have and use a 600C, but there's no modern optic to measure it against in that focal length.

Bottom line: diffraction is the great equalizer, except when it isn't. And one ought not question another photographer's results without seeing them in person.

[Jody_S]

What variables might have inlfuenced the outcome?

The most obvious variable is that the lenses are used and might be out of tolerance from factory specs, have cleaning marks, etc. And there is obviously some variation in lens performance even when purchased new. Shooting at f64 does tend to amplify surface defects on lenses, no? So the difference between the Fuji 300C and the Nikkor 300 might be attributable to cleaning marks on Fuji's somewhat soft older coatings.

[Sal Santamaura]

The most obvious variable is that the lenses are used and might be out of tolerance from factory specs, have cleaning marks, etc...

All lenses I own were either purchased new or, if discontinued models, bought after extensive searches for pristine examples. There are no cleaning marks on any of them. I did end my first post in this thread today with the phrase "usual sample variation caveats."

...So the difference between the Fuji 300C and the Nikkor 300 might be attributable to cleaning marks on Fuji's somewhat soft older coatings.

I mentioned having owned a 300mm f/8.5 Fujinon C and selling it due to low contrast, the only such experience I've ever had with a brand new lens. The recent comparison test between my pristine 300mm f/9 Fujinon A and my 300mm f/9 Nikkor M at f/32 could not have been influenced by cleaning marks on the Fujinon -- there are none, period.

[Drew Wiley]

Here is the kind of thing I have every reason to quibble with. Let's take that 450C for example. People stick that on a 4x5 with insufficient support, obviously a long
bellows extension, maybe a stupid ballhead, then lo and behold, get less than ideal results. Or they forget what a huge image circle of light it collects, so don't
shade it sufficiently. On the other hand, I wouldn't hesitate to use it even with a roll film back because it's so damn sharp. All these optics degrade a bit below
f/32, then dramatically more between f/45 and f/64. Just depends on your degree of enlargement whether this is a practical issue or not. Then, let's take my Fuji
360A. The Kern dagor might be a legendary cult lens, but is nowhere in the same league. Nor is any general purpose plastmat I've ever used. But again, it has a
big image circle and one has to be conscious of flare, though the multicoating does handle this a bit better than the equivalent G-Claron. I base this on big Cibachromes directly enlarged. Once somebody starts talking DPI the whole question is skewed by digital complications of distinctly lower expectations. Holder
depth means nothing if this pertinent variable isn't in relation to a vacuum system of perhaps adhesive holder. Anytime I enlarge bigger than 20x24 I use a precision back, otherwise nitpicking alleged lens variables is MEANINGLESS. Every single lens you've mentioned so far is capable of superb results. Very few
filmholders are adequate for the task. And don't forget the variable of shutter vibration, which of course its directly related to the mass, extension, and support of any given camera itself. For example, my Fuji 600C gives me quite sharp results with my 8x10 folder directly atop a Ries tripod (assuming no wind), but my
4x5 Norma has a problem with that big shutter; yet no problem at all with a 450C in no.1 shutter. So apples to apples, even very similar optical designs like
355 G Claron vs 360 Fuji A : the Fuji will give sharper results due to the lower vibration small shutter, yet impose a bit of mechanical vignetting due to that same
shutter in ULF situations (no problem at all with 8x10). All kinds of variables come into play. ... So now lets throw in the Nikkor M remark. It's a way smaller
image circle than a Fuji A; so yes, maybe center of image performance will differ; but the A is going to have distinctly better edge and closeup performance, esp
on 8x10 film. But I'd defy anyone to distinguish which of these two lenses made an immaculate 30x40 high gloss (polyester) print from 4x5 film itself. Even a low power loupe wouldn't do it, nose up to the print. At a certain point it's all overkill. If I'm on a long backpack trip, I'll pack the M for its light weight. If I'm
shooting closeups or 8x10, the Fuji A is the superior optic. I don't even use the Kern 14" much anymore. But then again, in most cases you probably couldn't even distinguish in print when I have. I just don't like that bigger shutter on 4x5 - want more mass behind it.