Nikon SMZ-10 microscope camera adapter

I bought an old Nikon SMZ-10 trinocular microscope and wanted to connect a camera to it. But it didn't fit out of the box and I couldn't find any information about connecting a camera to it on the Internet.

The microscope came with a "TV lens" thing inside the camera port. 

When I tried to fit my camera with 1/1.8 sensor size I got only a small part of the frame. I guess it is because the "TV lens" is design to project an image to a quite big sensor.

So, I bought 0.35x camera adapter on Aliexpress. Unfortunately I couldn't make it work with the original "TV lens" thing. To properly focus with 0.35x adapter I needed to position this adapter lower then "TV lens" allowed. And without this "TV lens" thing I couldn't get a focus no matter how I positioned the parts.

I decided to make my own "TV lens" thing that would allow me to position 0.35x adapter lower. It worked. I got a decent image on the camera. It is a bit cropped comparing with what I see in the eyepieces.

 Theoretically a camera adapter with higher image reduction might give more view field but I could not find anything lower then 0.3x on Aliexpress. 

Another thing that I noticed is that the camera image at lower magnification (0x66) is not that sharp. I tried different things and adding an aperture in the optical path helped. The aperture should be placed in the path where light is parallel, i. e. before the first lens in the camera port path. It is a bit tricky but can be done with a pair of tweezers. 

Here is the image comparison with the aperture disk installed:

The aperture also increases the depth of field which might be helpful.

I'm not an expert in optics and microscopes and all this was discovered by trail and error.  If anyone has some information on this matter I would much appreciate the comments. Thanks.

Video demonstration: