I wondered if anybody had any understanding of how microscopes work better than I do as I know zilch. I usually use my USB microscope which works like a dream for what I want it to do. I have 3 other microscopes, 2 of which are a bit more expensive. My 2 better ones are both Compound microscopes. The one I prefer to use has a much closer zoom than any of my other microscopes and also has a screen on the top so I don’t have to crane my neck 24/7 to look down an eyepiece. The issue I have is that the image is so dark when I zoom in. I know this is generally something that happens with microscopes - the closer you get, the darker the image. However, I can’t figure out how to fix it or even improve it ever so slightly. For example, the closer images look like this:
I’ve tried turning off the underneath light but that doesn’t do anything. I have tried shining flashlights and all sorts onto it from above to try and make the image brighter but it has a very minimal impact.
I wondered if anyone knows how to fix this at all and, if so, could someone explain it to me in layman’s terms? I know so little about these things, I need it explained like I’m 5 years old 
Thanks!!
There are two issues. Firstly, as you bring the microscope guts nearer to the subject the microscope blocks out the ambient light, and secondly as you zoom in you’re spreading the light reflected from smaller and smaller bits of the subject over the same area of image.
One answer is to use a ring light/illuminator, which is a thing that is fitted to the end of the microscope, and shines light on the subject. Ring lights cost from around a tenner, to hundreds of pounds; I can’t tell you whether the more expensive ones are worth the extra money.
I have a similar problem with handlenses and cameras - it’s often difficult to take a close look at something in the field, or take a macro photograph, because the ambient light is being block out by the handlens, the camera, or myself. (I did have a handlens with a builtin LED, but it didn’t work for long, but while it did work I could see the value.) You can also get ring lights for cameras; I have the impression that professionals use them for portrait photographs.
Someone else will have to advise you one which ring lights (if any) are suitable for your particular microscopes.
(How microscopes work is a bit of high school physics that I’ve forgotten, but I don’t think it’s actually relevant to your question - all that you need to understand that they take light emitted from the subject, and spread it over a larger image.)
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Another thing that can happen with zooming is that a bright bit in the subject that falls out of shot during digital zooming is likely to continue to throttle back the gain keeping the image dim.
