First of all, I replaced the tripod tube, there are quite standard 16 mm diameters, I took a piece of aluminum tube from Leroy. Under the microscope, you can now put the device being repaired as a whole. This is about 2 times larger than the standard lens. It also became easier to focus and the depth of field became larger due to the fact that the object of observation moved away.

Replacing the microscope lens for soldering.

It is easy to see that these are almost the same lenses, from which I conclude that the same lenses are put in microscopes as in surveillance cameras. Due to the increased focal length, there is not enough focusing distance in the lens mechanism. I wanted to increase the magnification, but it turned out only to increase the distance. With a standard lens, the maximum distance from the lens to the board is 7 cm, and with a new one, while maintaining the same magnification, it is already 17 centimeters.
After playing with the microscope I realized that I wanted more magnification, scrolling through Ali found the cheapest lens of 30 mm focal length there. What might be interesting for soldering Unable to get maximum magnification. I bought an interchangeable lens for the microscope. The focal length was chosen empirically, at random. I replaced the tube and the lens, but the result was not what I hoped for. Actually, the hero of the review is on the right, next to the standard one. On the other hand, the working area under the microscope has radically increased.