How the hell do I take high quality thin section photos ?

Photo 1 is a picture of a basalt taken with an iPhone 13 Pro Max through the eye pieces of a microscope.

Photo 2 is a picture of the same basalt, but taken with a Nikon D3500 DSLR Camera in the trinocular port of my microscope

Photo 3 is a professional photo I found on the internet for comparison to mine.

Picture 4 is my microscope

My microscope was made in India by a company called radical scientific equipment and it’s their model RPL – 55. I bought an adapter that attaches to my Nikon that gets it to fit in the trinocular port

I’m not sure if the microscope is not good enough or if it’s just because I’m an amateur at using this new microscope and microphotography.

The images also get out of focus the closer you get to the edge of the photo. Have a couple guesses why that is that probably isn’t my fault but rather the thin sections thickness (could be something else.)

Truly am trying to chase perfection here if at all possible for me