Fujinon-C 600mm F/11.5 Telephoto vs. Long Lens?

[LFLarry]

Unrelated question.

I read an article by Spencer Cox that his Fujinon C 600 is in a Copal 3 shutter and the aperture markers go to f/64, but he takes advantage of the fact that the shutter can still be stopped down past the f/64 marking on the shutter.

My question: is there a way to confirm the apertures beyond f/64 (i.e., f/90, f1/128, etc) beyond doing it with trail and error?
I assume if I can find a logical way to determine the smaller apertures that I could use a white paint pen and mark the proper location.

Text from the article below for context:

"To be specific, with a 600mm lens, f/90 will give you as much depth of field (and diffraction) as a 45mm lens on full-frame digital at f/6.7, given the same print size. That’s not awful, but it’s not as much as I’d like. Ideally, you’d be able to stop down to at least f/180 with lenses this long, which is closer to f/13.3 equivalent. Copal shutters are usually preferable in this regard. My Fujinon C 600mm stops all the way down to f/256 in a Copal #3 (even though the shutter is only marked to f/64)." Source: https://photographylife.com/best-lenses-14x17-12x20

[Drew Wiley]

The effect of diffraction all depends on the scale of enlargement. I have made big precise 30X40 inch Cibachrome prints from Fuji C 600 shots mostly at infinity, and never beyond f/45. But on a 1:1 8X10 contact print, the effect of diffraction might not even be visible due to a much smaller stop than even f/90. It also depends on your depth of field strategy and esthetic priorities. But for smaller than f/64 stops, one put supplementary marks on the shutter ring corresponding to those, or have a service like SK Grimes to it.

[Vaughan]

My question: is there a way to confirm the apertures beyond f/64 (i.e., f/90, f1/128, etc) beyond doing it with trail and error?

Later model Copal 3 shutters have linear aperture scales: the aperture pointer moves the same amount for each stop, compared to early shutters that have a non-linear scale where the numbers bunch together as they get bigger.

With the later linear-scaled shutters, just measure some more marks.

[Greg]

is there a way to confirm the apertures beyond f/64 (i.e., f/90, f1/128, etc) beyond doing it with trail and error?
I assume if I can find a logical way to determine the smaller apertures that I could use a white paint pen and mark the proper location.https://photographylife.com/best-lenses-14x17-12x20

Works for me... just mark the same distances between the "lower" full f/stops... I have no problem using f/90 with my 11x14. FYI: I am making contact prints.

[LFLarry]

That is really good to know. I didn't realize that. That makes it super easy then!

Later model Copal 3 shutters have linear aperture scales: the aperture pointer moves the x=same amount for each stop, compared to early shutters that have a non-linear scale where the big numbers are bunched together.

With the later linear scaled shutters, just measure some more marks onto the scale.

[LFLarry]

I wanted to confirm the apertures beyond f/64. Is this correct? f/64, f/90, f/128, f/180

Works for me... just mark the same distances between the "lower" full f/stops... I have no problem using f/90 with my 11x14. FYI: I am making contact prints.

[Drew Wiley]

Just for fun, I looked up current asking prices on EBay : they're asking ten times as much for a typical 600C than a Fuji 600 T. Most obscenely overpriced of all were a couple of 360A's, with the one trending almost to 6K being the older single-coated version! Wonder how long they'll just sit there. 450 C's are also up to the stratosphere. Maybe they're thinking that if 8X10 film is four times the price it was a decade ago, why not cult 8X10 lenses too? Lenses are meant to be used, not hoarded. The super rare 600 and 1200 A's are probably behind six inch thick plexiglas beside the Hope Diamond.

[LFLarry]

Indeed Drew. Prices have elevated to crazy land...

Just for fun, I looked up current asking prices on EBay : they're asking ten times as much for a typical 600C than a Fuji 600 T. Most obscenely overpriced of all were a couple of 360A's, with the one trending almost to 6K being the older single-coated version! Wonder how long they'll just sit there. 450 C's are also up to the stratosphere. Maybe they're thinking that if 8X10 film is four times the price it was a decade ago, why not cult 8X10 lenses too? Lenses are meant to be used, not hoarded. The super rare 600 and 1200 A's are probably behind six inch thick plexiglas beside the Hope Diamond.

[Vaughn]

I wanted to confirm the apertures beyond f/64. Is this correct? f/64, f/90, f/128, f/180

Yes, that is correct, with f/256 after that. All my work is contact printed (alt processes), so working with f64 and f90 is just a matter if the light, the wind, and I all have the time to hang out for awhile. A 600mm lens for 11x14 really isn't very 'long'....about half again of normal?

[xkaes]

Fuji didn't use many Copal shutters where the aperture numbers are not evenly spaced. All of the C-lenses have evenly spaced f-stops. This same approach can be used on most Fujinon lenses with Copal shutters -- if you dare.