I shot some images for use in a blog post. With the closeups, I ran into the problem of too low depth of field. Because I only need them for the web, I think that the easiest way to solve it would be to take them from farther apart and then crop them instead of downscaling. Now I need some guideline about how far away I should stand.
Let's say that I took a picture at X cm distance between subject and sensor, and the subject fills the 4000 px wide picture. If I want the same object to be at least 640 px wide, what is the farthest distance I can have between subject and sensor?