For more (much more) general information, I recommend the Nikon site and the Olympus site.
Shown in the photo above is (almost) the full selection of condensers for Nikon Labophot, Optiphot and Diaphot (at least) microscopes.
Nearly all of them have an iris diaphragm to control the numerical aperture (NA) of the incident light.
Zig-zagging from the top left are:
Abbe 1.25
Achr 1.35
Universal Achr-Apl 1.40
Phase Contrast 1.25
Phase Contrast Long Working Distance 0.52
Hoffman Modulation Contrast (10x, 20x, 40x) from Modulation Optics, Inc.
DIC Long Working Distance 0.52
Achr 0.9 Flip-Top
Phase Contrast-2 1.25
And Phase Contrast-2 Extra Long Working Distance 0.3, which is two parts - the lens and the turret.
Not shown here is the slightly different condenser system for the Eclipse series, which does seem to use the same dovetail, so could be used with these microscopes. It is an Abbe 1.25 with an iris, as well.
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