Lens switch on Copal 3 - aperture correction... have I got this right?

[Daniel Grenier]

I want to mount my 355 F9 G-Claron in my F5.6-64 scaled Copal 3 shutter.

Let's see now. To properly compensate, I'd have to close down the shutter by a factor of 1.6 (f9/f5.6= 1.6). Right? Or have I got this wrong?

[Ole Tjugen]

Wrong.

It depends on what focal length the aperture scale was made for - and what lens type, too.

BUT: If the G-Claron is wide open when the aperture is set at f:5.6, then if the aperture blades become visible immediately as you begin to close the aperture, then you idea would be correct. About 1 1/3 stops, in that case.

[Daniel Grenier]

Thanks Ole.... BTW, the original lens is a 240 Rodenstock Sironar F5.6 - 64