This page contains an interactive calculator for depth of field, effective aperture and suggested slice depth when stacking images.
The calculator is biased towards my equipment- if you have specific lenses, CoC values, apertures, etc you want adding just let me know.
You can get bogged down in theory - s the way I work is to use these values as a starting point and then check what happens in practise.
Simple symmetric lens
First for a typical use of a reversed enlarger lens on a bellows, modelled as a symmetric lens, to give around 1 to 5x optical magnification we have:
The next case is for using microscope objectives. The ones I have available are for finite tube length Nikon ELWD and SLWD PLAN versions. the Depth of field formula is a bit different this time and takes into account the refractive index of the medium in which the sample is immersed and the wavelength we are using. I only use air (you can increase DoF by using oil or high refractive index liquids) and usually consider 550nm (or 0.55 microns) as an appropriate wavelength.
El_Nikkor 50mm f2.8N Enlarger lens reversed on bellows - terminology