Biorad MRC500/600/1024

This is part of the Backprojected Pinhole Calculator.

Details (read carefully!!!)

The diameter of the circular pinhole is reported by the microscope in millimiters. Use this reported value as an input in the form below.

The fixed system magnification is reported to be 53.2 (this is a value received from Zeiss CS Customer support, <a href=%22#Pawley_95%22>Pawley 95</a> reported 53), but see Check Biorad Magnification.

Pawley 95 also reports the following:

  • Extra 1.25× magnification is introduced by the fluorescence attachment.
  • Extra 1.25× magnification is introduced by the differential interference contrast (DIC) attachment.

The Zeiss customer support said:

The additional magnification values are taken from the "known (printed on the side!!!)" magnification of the additional components in the microscope; for example, in the case of the older Nikon Optiphot 2 upright microscope the epi-fluorescence module has a fixed 1.25x mag lens in it. This lens compensates for the change in the tube length of the microscope (160mm non-infinity optics). The DIC attachment for this microscope had a similar compensating optic which also fitted between the objective revolver and the trinocular head, which may have been 1.25x, hence Jim Pawley mentions it.

Additionally, some "up-to-date" microscopes have a magnification lens that can be switched "in" at the users discretion. E.g. I think the Olympus IX-70/71 has a 1.5x and 2x magnifier that can be switched in and out. Other microscopes may also have this type of switchable component.

Typically, none of these components are recommend to be used when imaging in confocal mode, but are unavoidable in the case of the older microscope which have the optics built in.

This should be confirmed experimentally, like in Check Biorad Magnification. If no extra magnification is seen, uncheck both checkmarks on the form below. Each checkmark introduces a extra 1.25× magnification. Alternatively you can forget the checkmarks and introduce the total internal magnification (not including the objective's) in the correspondent entry field, replacing the default 53.2.

Pawley 95: Pawley, J. B. Handbook of biological confocal microscopy, 2nd ed. 1995. Plenum Press, New York and London. ISBN 0-306-448262. Page 30.


Pinhole diameter (mm)
Objective magnification
Internal system magnification
Fluorescence attachment
DIC attachment