3 G Clarons, 1 Shutter

[Eric Mac]

Greetings

I have a 240 G Claron in a barrel and a 210 G claron with a Copal 1 shutter. What is the f stop conversion from 210 to 240 to 305 (assuming I get one). Somehow I recall seeing if it is set at 210@f11 the other focal lengths fstop equivalents would be 240@f13.5, 270@f16 and 305@f19, but I can't seem to find it in the various archives.

More likely there would be a formula for this?

Thanking all in advance
Eric

 

[L Gebhardt]

Greetings

I have a 240 G Claron in a barrel and a 210 G claron with a Copal 1 shutter. What is the f stop conversion from 210 to 240 to 305 (assuming I get one). Somehow I recall seeing if it is set at 210@f11 the other focal lengths fstop equivalents would be 240@f13.5, 270@f16 and 305@f19, but I can't seem to find it in the various archives.

More likely there would be a formula for this?

Thanking all in advance
Eric

You should be able to convert to the aperture size and then back to the other f stops. F/11 on a 210 is 210mm/11 which is 19.09mm. 240/19.09 = 12.6. You should be able to do this for all the combos. For each lens you can actually just calculate out a factor (the 210 to 240 factor is 1.14x stops so open up 1/3 of a stop). The 305 should be 1.45x or about one full stop.

 

[jimgalli]

They're 1/3rd stops apart. 210-240-270-305. 305 being a full stop different than your 210.

 

[BradS]

They're 1/3rd stops apart. 210-240-270-305. 305 being a full stop different than you're 210.

Interesting....I wonder if they intended it this way or, if they chose that sequence of focal lengths due to market demands....

Ponder this, I will.