Hi, I've bought an used set of Hasselblad extension tubes: 21, 32 and 55 mm. I'll use them on a 500 C/M body with 80 mm lens. What is the light compensation I have to apply? Is there a tabel on internet riassuming these data?
and use As.Focal length instead of the true focal length in the above mentioned formulae.
The clearsight tables do not do this, though the difference between these 'plain' and 'asymmetry corrected' values can be surprisingly large.
Remember that the focussing helicoid is providing extension too.
The clearsight tables give one compensation value for each lens-tube combo, but since you can use the focussing helicoid too, they should show the upper and lower limit of a range.
You can deduce the amount of built-in extension using the above formulae and the minimum focussing distance.
But you can also measure the differences in physical length of the lens set to infinity focus and minimum focussing distance.