Is there a quick rule of thumb for working out the depth of field for a given aperture focal length and focus distance? I know some prime lenses have a little scale on them (my Nikon 18-200 zoom doesn't), and whilst there are some on-line calculators, that's not especially helpful in the middle of nowhere!
Just something I've been struggling a little with trying some close up stuff - trying to get the full depth of the subject in focus, then leaving the rest of the image soft. Currently ending up with far too narrow a d.o.f, despite what feels like relatively small apertures.
Thanks!
