The table below describes the relationship between the optical resolution (R) theoretically possible with each objective and the maximum zoom factor which captures that resolution. The optimum zoom factor is based on the Nyquist theorem, that one needs at least 2.3 pixels per object to resolve two closely spaced objects.  This translates into a pixel size of R/2.3.

The starting (1x) pixel size used here is based on an field size of 1024x1024 pixels for each objective.  You can see that as the Numerical Aperture increases, the usefulness of zoom decreases. Any zoom factor larger than optimum enlarges the image without increasing resolution.  Note that essentially any zoom using the 100x objective provides "empty" magnification; magnification without increased resolution.

To calclulate optical resolution for dyes/objectives not listed,
click here:

A discussion of the relationship between Depth of Field (DOF), and z-series step size, as well as a DOF calculator, can be found on the Depth of Field page.