Quote Originally Posted by Bob Salomon View Post
Do you really need it?

Life size open up 2 stops, half life size open 1 stop, twice life size open 4 stops, quarter life size open up ½ stop.

It is a progression, most don’t need an app. Just 2 rulers, one at the scene and one at the gg.
Experience talking here and I absolutely agree. I use the Calumet wafer for the same net effect. Clearly there are a lot of mathematicians, engineers, scientists in LF/ULF photography that feel empowered to develop any number of iterations for bellows correction. But any measurement irrespective of how "careful" it is deployed and the computation that follows plays second fiddle to the image on the ground glass. And that is all that matters.