Diaphot microscopes are typically used with long working distance (LWD) condensers, but the question came up about compatability with high NA condensers, such as the 1.25 Phase Contrast. This comparison shows different settings of the condenser turret with a variety of objectives. In each case, the view through the Bertrand lens is shown to complete the comparison. Some testing was done with the built-in lens removed, as well.
The specimen is a diatom test slide arranged by Carolina Biological.
A couple of basic observations: the condenser is upside down compared to using in on an upright 'scope, so the labels on the turret positions are not easily visible. Secondly, LWD condensers can be used with open "well slides" effectively, but with the high NA condenser only 1-2 mm away from the slide, an open slide evaporates ... directly on the condenser lens above it, causing water droplets to form on the lens, which is certainly not ideal!
My basic conclusion is that this condenser will generally work on a Diaphot, with a reduced field for very low magnificaions (which you would likely want a LWD condenser for, anyway.)
All photos were taken with a 100 Watt lamphouse installed on a Diaphot TMD with a Nikon D3300 APS-C camera (6000 x 4000 pixels) on the front port. Crops (100%) are therefore about 1 MP out of the 24 MP image.
You can see the effect of the standard condenser field lens is to drastically increase the field with a 2x objective. However, even with the lens installed, this condenser is not ideal for 2x.
Unfortunately, I didn't take a picture through the Bertrand lens for the rest of the 2x tests. This one is with the Ph2 aperture offset from center.
Next, we close down the aperture stop, reducing the NA.
This image is taken with the condenser aperture just at the edge of the objective. Opening it further decreases contrast with no improvement in the resolution. Here (2.0 MB .GIF) is a demonstration of the trade-off between resolution and contrast as the condenser aperture is opened.
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