I am using a microscope with an LED derived light through the epi-fluorescent port of a microscope. I know that the "field of view" for a given objective is equal to the field number/magnification but I don't know that this is the actual area of illumination on the sample. In my case, I am using a 40x objective with field number 26.5.
Secondly, if I were to use a pinhole filter between the light source and the back of the objective would this limit the area of illumination so long as the pinhole was smaller than the f.o.v. dimension?
I would be grateful for any answers, most of the information I can find on beam size at sample is related to spot size calculations of resolution.