There are folks out there, that instead of using an infinity corrected objective on a microscope, use a 200 mm focal length lens, which is optically similar to what happens inside an infinity corrected microscope (it is called a tube lens), on their regular camera. Finite objectives don't use another lens, but do need a way to get the finite conjugate right (like 210 mm, or 160 mm), blocking out stray light - typically this is done with a focusing bellows arrangement.
You can read more about this technique on the photomacrography.net site, here. One of the masters of the craft is Johan, in the UK, who's excellent site is extreme-macro.co.uk.
My first real attempt with my Nikon D3300 DSLR, with a 2x Mitutoyo M Plan Apo (clone, by Edmund Optics) objective on a 55-200 mm zoom lens, at 200 mm, was of a Japanese Brown Beetle's head.
You can go much higher than 2x, but it takes some effort to keep things stable and do proper focus stacking, most likely.
The same subject was photographed with what is called a "combo lens", where multiple lenses are used together, but not an actual objective. Here I use the Nikon lens with a 39 mm threaded old Soviet fixed focus lens (58 mm f/2 - the original Helios 44) attached to the front.
Since I hadn't been working on the interference 'scope yet, I decided to use the granite base, vertical stage and 5-axis stage for extreme macro photography. I used the arm sticking out to mount the camera via an interface plate on top of the arm with a 3 inch hole in it and a tilted box beam, which cancels out the 10° tilt of the top of the arm. It simply holds the camera by the 1/4-20 mount on the bottom of the camera. There are slots for vertical adjustment and slots in the box beam for front/back adjustment. Left/right pointing can be modified slightly with the positioning with the 1/4-20 tensioning it.
The vertical stage has a coarse thread giving only 20 turns per inch, which is 0.05" per turn (1.27 mm/rev). A direct drive stepper motor with 200 steps/rev yeilds 6.35 microns per step, if I were to hook one up.
The photos below are with a Nikon D3300 with Nikkor 55-200 mm zoom lens and an Edmund Optics 2x Plan Apo Long Working-Distance microscope objective. I have also used it with a 20x Mitutoyo LWD objective and the Helios 44 combo lens.
On to some examples! Using the vertical macro rig described above, the following images were made as described below. These are all reduced in size from the original 24 MP images (or larger in the case of stitching). I can put up higher-resolution images if people are interested.
Here is a 21 image stack, using Zerene Stacker of moss with the Edmund 2x.
Also stacked with Zerene (12 through focus) is an M2 x 4 mm bolt with the Edmund 2x.
Stacked with ImageStacker (7 through focus) is your standard table salt and pepper with the Edmund 2x.
A Zerene stack (11 through focus) is of the pattern in a silk shirt, but this time with the 20x Mitutoyo Plan Apo LWD objective.
Here I did no focus stacking, but it is stitched in Microsoft ICE, combining 9 images.'
With the Helios 44 combo lens, I looked at the salt and pepper again, here stacking (3 through focus) with Image Stacker. The magnification depends on the focal length of the lenses, so the zoom lens functions as normal, providing variable magnification.
Also with the Helios 44 combo lens, I both did focus stacking with Zerene, and stitched the three sets of output stacks in Microsoft ICE, creating a 53 megapixel composite image from ~80 source images. (In stereo.)
Using a reversed 105 mm focal length medium format lens for the Pentax 67, I obtained the following stack of 37 images of a fly. (In stereo.)
And using a reversed 165 mm focal length medium format lens for the Pentax 67, I obtained the following stack of 97 images of a palo verde blossom. (In stereo.)