I am not an expert by any means. But I think the right combination of magnification and mega pixels is important. The nice thing about Amazon is that you can return. Save the box and packaging.
If you don't have enough pixels, and you enlarge it from the base level ( lowest magnification) the software adds extra pixels so there is no hole in the image, but since it isn't really there, it has to fake it by comparing to surrounding real pixels and adds one hoping no one notices. as the human brain can move the eye a small vibration so it can scan the lens image over the rods and cones ( like pixels in the camera) and the brain then can "stitch" the image together and convert it to memory form. If the averaged non-diseased human eye was measured it would have over 550 MP, so a good glass lens with the human eye are the very best way to see actual real detail that is present. A digital camera even on cell phones or ipad devices have 8+ MP ,so I would think a minimum level for enlargement would be that range if you are intending to enlarge every tiny structure into a blurry blob which is common here from some. Some digital cameras claim they magnify 50, 100, 500, even a 1,000 times, but they are talking about the max of the SOFTWARE produced image, not the actual data of true sharp image. If you have a 100X USB camera here is what 100X looks like with a lab microscope. These are the fields of a UNC Morgan dollar on the left and unc Peace dollar on the right in a post regarding more colorful natural toning on Morgan, more ridges, more refraction, than the peace. jim This is a photo of the Morgan surface at 400X with a lab, you can see the ridges. There is a little of 'out of focus' areas as the higher the magnification , the less the depth of field of any lens. The camera shooting through the microscope lens was a canon point and shoot of 5mp and this was almost a decade ago. Jim
There's one member here whose name I've forgotten that is an expert on photographing coins. His first name might be Ron? I wish he lived near me so I could learn something. Anyway, I have a very old Kodak Easy-Share Z700 That does not have what it takes for good photos. I tried a few years ago, bought myself a tripod even, but was not able to position the camera lens directly perpendicular to the coin. I hope you all can arrive at something satisfactory.