Pen F Bellows Exposure Compensation?

[flip]

The rails are marked in cm. I wonder how to compensate for exposure with my fv....

Thanks!
Phil

 

[Landshark]

I don't even try to remember the math. It's more accurate but........I'm lazy.
With any camera/lens with magnification @ 1.5X increase 1 stop, @ 2X increase 2 stops. 2X is twice the focal length of the lens you're using.
With a 38mm, 2X will be 76mm extension from the film.

 

[flip]

haha. OK. Thanks.