Lens compatability with close-up filters

Aaaaron wrote:

Not sure of the etiquette here, I posted in the question section but I would benefit from a little discussion on a couple of points made in the very useful responses I have received. I really appreciate that people taking the time to lend a hand.

AeroPhotographer wrote:

I always just use a crop out of the center and discard the edges.

Very pragmatic!

You can ignore the edges too, just shoot from farther away. Furthermore depth of field increases with distance squared. So an increase in distance is very beneficial.

"Increase in distance" Assuming that you mean the distance between the lens and the objective, I don't observe much if any change in depth of field. The available change in distance is narrowly confined by the close-up lens.

Does distance mean zooming in and out? If so, should I choose a higher diopter and work at a shorter focal length? As you say, an increase in depth of field would be very useful. I feel it is essential that I understand this relationship before I find myself lying in the mud trying to compose a shot of the first fill-in-the-blank of spring.

Alan

Increasing distance only increases depth of field by distance squared when you do not change focal length. To be exact depth of field is proportional to (distance/focal length) squared

distance / focal length = 1 / magnification.

see https://www.dpreview.com/forums/thread/4624325

The autofocus with added lenses tends to be best with minimum lens diopter. Focal length of added lenses = 1000 / diopter. A diopter = 2 lens has a focal length =500mm. If the camera will autofocus, it's best chance will be when the lens is approximately 500mm from the subject.

I experiment with added lenses on print to determine their autofocus performance.

Alan