tamar

If it were my lab, I would not try to use a still camera at all, but rather put the plate down on a programmable grid and aim a video camera at it. You don't need a microscope and if you are clever enough, you can write pattern recognition software to count for you.
Bill

Thanks Bill,
I really have zero knowledge in photography, but I intend to learn.

I guess using a video camera would require a sliding mechanism for the plates to ensure a fixed rate of movement - or not necessarily?
Can you elaborate on the technical details?
Thanks!

Ideally this sort of experiment should be designed with a simple way of doing such photography in mind before starting - easily said after the event!

true.. It was planned to be done manually, but after a while I decided that in order to keep my sanity safe I must find some automatic solution (also, using photography and analysis software can yield some additional data - size and distances between specimens, etc).
The plates are indeed removable - and counted in lab.

following on from paul's suggestion, could you keep the camera fixed and move the plates beneath it?that way lighting and camera position/ image plane could be fixed.

Yes, I also thought about building a frame with a fixed lighting.

Tamar

Most dSLRs should produce what you need but not necessarily in one photo. You will need a decent dSLR (~10MPixel) with a good macro lens capable of 1:1 photography. You can then try taking say 3x3 shots (= 9 of each plate) which should give a good yield of information. Good 'stitching (panorama) software is available these days and this will allow the images to be stitched together to produce one large file if required so that you don't over-count things. The biggest problem that you face is positioning the camera and if I were doing this, I'd make up a small frame which allowed the camera to be positioned accurately and repeatedly to make taking the photos quick and easy - something like a plate with 9 holes i for the lens to drop into - you'll need to be ingenious to sort it out but it shouldn't be impossible and there are a number of ways to do this. I have a similar job where I need to photograph a very rare plant colony for monitoring purposes. I take multiple shots and these are then stitched together and each individual plan can then counted - it works very effectively indeed.

Thanks Paul!
Can you recommend such a suitable dSLR (minimum price vs best efficiency)?