The famous [Group *f*/64](http://en.wikipedia.org/?title=Group_f/64), to which Ansel Adams and several other prominent photographers of that day belonged, were named that because of the f-stop: > The term *f*/64 refers to a small aperture setting on a large format camera, which secures great depth of field, rendering a photograph evenly sharp from foreground to background. Such a small aperture sometimes implies a long exposure and therefore a selection of relatively slow moving or motionless subject matter, such as landscapes and still life, but in the typically bright California light this is less a factor in the subject matter chosen than the sheer size and clumsiness of the cameras, compared to the smaller cameras increasingly used in action and reportage photography in the 1930s. I presume that was for either a 4×5" or an 8×10" large-format camera. I will presume the latter in my question. When you capture images on a medium- or smaller format, the magnifications needed to make an 8x10" print increase from the 1:1 contact print of an 8x10" capture. Therefore, just saying something is f/5.6 doesn't tell you the depth of field achieved in the final print. From Wikipedia, we see this: ![size relations][1] or going the other way, you have this: ![bigger formats][2] *My question is:* ------ If the Group/64 used f/64 for a certain look in their prints with their equipment, what would be the equivalent f-stop in the other format sizes? * LF 11×14" — ??? * LF 8×10" — f/64 * LF 4×5" — ??? * Better Light LF Digital — ??? * MF: 120 film / 6×4.5 cm — ??? * MF: 120 film / 6×9cm — ??? * SF: 135 film / 24×36mm / 35mm / full-frame — ??? * SF: APS-C / 16×24mm — ??? * Average compact camera — ??? * Average cellphone camera — ??? Actually, if I just knew the formula based on the diagonal, I could fill out the rest myself. If an 8×10" transparency’s diagonal of 12.8" yields a certain effect stopped down to f/64, I figure we should be able to use a formula of some sort to derive all the others based on their diagonal. I just don’t know what that formula is, and would like to know, please. I feel like I’ve seen a list like the one I’d like filled out above from [Roger Clark](http://www.clarkvision.com/), but now I can’t find it. [1]: https://i.sstatic.net/Nt7A3.png [2]: https://i.sstatic.net/IuYIO.png