M27 RMS Thread conversion DIC/darkfield question

I have a M27 thread Epiplan -NEOFLUAR 20x/0.50 HD DIC objective.

However, the threads I have on my microscope turret are for RMS threads.

If I buy a M27 to RMS adapter (roughly 27mm to 20mm constraining), am I losing functionality of either: 1) Reflected DIC ability 2) Reflected Dark Field ability

I am concerned using the adapter wouldn’t allow light in the outer ring of the objective. I believe this outer ring is for dark field functionality but is this necessary for reflected DIC?

Is the proper way to do this to buy a M27 turret and if I need to use an RMS objective I use a RMS to M27 adapter? Is it a possibility that the microscope itself could be incompatible with larger sized objectives (Zeiss Axiophot El-Einsatz 45-18-88)

Appreciate any advice since I am still learning from the firehouse of information from all the types of objectives : )