The f-numbers that are mentioned are always the marked f-numbers. But of course the calculations take the magnification into account, thereby with the same effect as using Neffective as N(1+M/p) where M is magnification and p is pupil size. I strongly encourage you to look att Jeff's paper that I referred to for mathematical details and explanations. I have to apology that my post has three duplicate graphs at the end. I made a mistake, discovered that, then edited the post to delete them, tried to save the edit, whereupon I get the following stupid response from the stupid photo.net system: "Your content can not be submitted. This is likely because your content is spam-like or contains inappropriate elements. Please change your content or try again later. If you still have problems, please contact an administrator." That's absurd! It refused me to save! After 15 minutes it even refused me to go into edit mode! It's embarrassing with several duplicate images in the post! I have messaged both an admin and a moderator for help, but no one has responded. Actually, I think I should not have posted it at all in this thread – rather I should have referred to the article I just published on that subject. Also because I got some small comments from Jeff, which I used to update the article with a couple of language issues and a couple of references plus some small clarifications. The updated article can be read here: What is the optimal aperture for camera scanning?