Aperture re-scaling

[iangreenhalgh1]

Hi folks

I just put a Schneider G-Claron 9/150 in a Compur 0 shutter than formerly held a 4.5/105 Kodak Anastigmat.



Obviously, I need to work out the aperture values for this lens. What I'm wondering though, if the maximum opening is labelled 4.5, can't I just double the values and that will be close enough? Or do I need to do some calculation and create a whole new scale?

[Attila]

Most accurate thing what you can do if use two digital camera one with normal lens , second with one of these and look each aperture on same light source and mark it with removable ink first and you able to decide what is next.

[luisalegria]

You have to do a new scale AFAIK, if you are going to be accurate about it.
There is the question of where wide-open begins, among other things.
Do you have the old aperture mechanism ? It looks like an old barrel lens you have there, if it had an aperture mechanism you're golden.
Thats a place to start. You can crib your scale from that.
Match the hole size that corresponded to f/9, f/11, etc. on the old scale on the new shutter aperture.
I.e., if f/9 on the old aperture gives a 16.5mm diameter hole, then you move the aperture on the shutter to give a 16.5mm diameter hole, and mark that as f/9
And so down the scale.

[iangreenhalgh1]

Sure, I still have the barrel, that sounds pretty easy, cheers.