The principle advantage of using an infinity focus with a telephoto is that you can use them for range of magnifications by varying the FL of the telephoto without introducing abberations that can result from the wrong tube length of a finite focus. This is not such a big issue with an NA of only 0.1, though. The focal length of the tube lens (essential a simplified telephoto) designed for the Nikon CFI60 series is 200mm. That results in the nominal magnification. For the subject image, I use a 300 mm telephoto, which results in a proportionately higher magnification (6 = 4 X 300/200). The other views linked required a larger field of view, so I used a 200 mm. I went to 6X for the anterior view to get a higher resolution (which is transitional between NA and pixel limited).

I have used this objective with a 135 mm telephoto for a magnification of 2.7X. You have to be careful doing this, though, because you are now exceeding the specified field of view of the CFI60 when used with a DX camera sensor (about 23 mm wide). Fortunately, for a CFI60 Plan Achromat 10X NA0.25 and (as I have determined) the subject CFI60 4X NA 0.1, there is there is little degradation out to the corners even with a 135mm. In the image I've reference below the corner degradation is significant compared to the center, but the corner quality is comparable to what I can achieve with my reversed Focotar-2 (a superb enlarging lens) at this magnification. I now only use the reversed lens for 1X to 2.7X, exclusive, where it does fine.

An another advantage of using the CFI60's specifically is that it is simply larger than the old RMS mounts (the 60 refers to its 60 mm parafocal distance). This means the WD is large for a given NA. The WD of the subject objective is 30 mm.

The DOF for this lens is indeed small (about 50 microns), but my stage can do increments down to 1 micron. I've posted stacked images on BG up to an NA of 0.55, and will soon try it with my recently acquired Nikon BD Plan 40X 0.65NA on some interesting mite tummies.

I do own a Lomo 9x 0.20 with a variable iris aperture, but have not used it since I discovered stacked imaging. It does not have the lateral chromatic aberration correction (without occular) of the Nikon's, but I'd only use at this point fully stopped down on live specimens (that cannot be stacked) where this should not matter too much. I've have good luck using HMDS to stabilized tiny soft bodied specimens, though, so haven't had the need yet. They would have to be doing something very interesting.

References:

Tube-Length tolerance vs NA

CFI60 tube lens

Subject CFI60 Plan achromat 4X 0.1 NA

DOF vs NA

Lomo 9x 0.20 with aperture

CFI60 Plan Achromat 10X NA0.25 Infinity objective on telephoto

My image with Nikon CFI60 4X 0.1NA Plan Achromat microscope objective + Nikon 135mm F4 telephoto lens

HMDS treatment

thanks for taking the time