Wrong aperture scale on Copal 0?

[afxstudio]

Hello everyone,
this is probably going to be a rookie question, but I just started with large format and I can't find all the answers to my doubts. I hope your understand.
I have a Fujinon SW 125mm f/8 mounted on a 4x5. Now the thing is that I'm not sure the aperture scale engraved on its shutter copal 0 is correct.
Having a max aperture of f/8 I'd expect the lens to be fully open at such aperture, but when set to f/8 the blades are slightly closed (i.e. I can see them) and I have to move the aperture lever all the way back to have them disappear. On the other side of the scale, things get even more weird. The aperture lever goes way beyond the minimum aperture of f/45, so when I move the lever past f/45 I can see the blades closing more and more until they leave a certain opening, which is significantly smaller than the one at f/45.
How can I be sure that, for instance, setting the lever to f/32 corresponds to f/32?

I actually found this https://www.photo.net/discuss/thread...-wrong.459661/ which seems to cover my question, but still I'd like to have your opinion on this.
I exposed some Fomapan100 so far, and even though I didn't take its reciprocity failure in consideration the results came out quite ok with my surprise. But I can't take such risks with more expensive and less forgiving positive slides such as Provia and Velvia.

Thanks for your help.
Max

[Hal Incandenza]

This is totally normal. On every Copal shutter I've used it's possible to stop-down beyond the smallest setting, usually at least another stop. The movement you describe while wide open is normal too. The settings are accurate, especially if you have a factory installed shutter, which I would think you have with an SW.

[afxstudio]

This is totally normal. On every Copal shutter I've used it's possible to stop-down beyond the smallest setting, usually at least another stop. The movement you describe while wide open is normal too. The settings are accurate, especially if you have a factory installed shutter, which I would think you have with an SW.

Thank you, Hal. So in other words, I can assume I'd be able to stop down past f/45 and reduce the amount of light reaching my film, but would that be calculable and, most importantly, viable and safe to do?

[Bob Salomon]

Thank you, Hal. So in other words, I can assume I'd be able to stop down past f/45 and reduce the amount of light reaching my film, but would that be calculable and, most importantly, viable and safe to do?

It would put you deep into diffraction so there is no reason to go beyond f22.

[Hal Incandenza]

Thank you, Hal. So in other words, I can assume I'd be able to stop down past f/45 and reduce the amount of light reaching my film, but would that be calculable and, most importantly, viable and safe to do?

You can extrapolate somewhat the additional f-stops. Just slide the aperture beyond the end of the scale and note the distance on the scale past f/45. That distance will roughly correspond to the number of stops spanned by that distance prior to f/45.

And as Bob noted, diffraction will be an issue.

[Corran]

It would put you deep into diffraction so there is no reason to go beyond f22.

How about, getting enough DOF?!

Not all subjects will fit inside f/22, even with movements.

Stop down as much as you need. f/45 is probably enough for most things. The stops on the Copal shutters are linear, not progressive, so you should be able to eyeball f/64 if you really need it and it goes that far. My Nikkor 120mm f/8 is marked all the way to f/64. Diffraction is a non-issue for most users who don't print to the massive sizes that would be required before seeing it.

[Bob Salomon]

How about, getting enough DOF?!

Not all subjects will fit inside f/22, even with movements.

Stop down as much as you need. f/45 is probably enough for most things. The stops on the Copal shutters are linear, not progressive, so you should be able to eyeball f/64 if you really need it and it goes that far. My Nikkor 120mm f/8 is marked all the way to f/64. Diffraction is a non-issue for most users who don't print to the massive sizes that would be required before seeing it.

First, focus,on the correct spot, 1/3rd into the scene so you take full advantage of the depth of field required.
Then use tilts and/or swings to control the plane of sharp focus.
Then stop down to optimal aperture to widen the spread of sharp focus.

[Corran]

I am well aware of how to focus my camera. Nevertheless, f/22 is not enough for DOF in many situations.

[Leigh]

Diffraction is a non-issue for most users who don't print to the massive sizes that would be required before seeing it.

Absolutely true.

- Leigh