The is my main set-up for studio for full frame and APS-C cameras and is based on M52/SM2 extension tubes and Thorlab slip-ring clamps. This set-up is ultra rigid, uses low cost parts, and easy to configure although the Thorlans ITL200 is my standard tube lens.
For a M42 x 1mm extension tube based studio setup, follow this link: https://www.closeuphotography.com/42mm-setup
52mm Studio Setup for APS-C and full frame sensors
As of early 2018 I am now using the Thorlabs/Nikon ITL200 tube lens setup as my standard studio system. A detailed review of the ITL200 and a tube lens image quality comparison is available here on Closeuphotography.com: https://www.closeuphotography.com/thorlabs-itl200/
The set-up is based on Thorlabs SM2RC slip rings used as clamps for SM2 tubes or Generic 52mm tubes. The Thorlabs rings are bolted to generic no-name $7 QR clamps. The clamps mount to a generic $10 no-name QR plate.
Originally I started working on this set-up for a Scanner Nikkor lens. I used to threaded collars on the front and back of the lens that mount inside the Thorlabs tubes. On the front of the lens I mount about Thorlabs tube to serve as a lens hood and to use a third clamp. With the Scanner-Nikkor the set-up is super solid, and it's quick and easy to dial in any magnification I need.
Infinity corrected microscope objective with the Sigma 200mm tube lens.
The Thorlabs SM2 tubes and a couple of unbranded 52mm extension tubes fit the Thorlabs slip-rings.
For this set-up I went with the lowest cost QR plate that I could find online. I paid $10 for my plate on Amazon, Ebay has lots of low-cost choices also. Look for clamps like the no-name version on the far left, it will give you unrestricted clamp movement.
Some plates tend to restrict the amount of travel for your clamps. Look at the image about, the left blue circle on the left side is over a Wimberly plate. Not only does the plate cost 5x the amazon plate but you lose maybe 3/4 of an inch for this legacy flash bracket that no photographer on earth even uses any longer! I recommend to skip paying the extra $40-80 for the Wimberly or RRS plate and buy a new lens with the money you save.
For QR clamps I used RRS knock offs made in China, and they work perfectly. RRS clamps are $70 each so save your money and buy the clamps I used for $13 for a pair with free shipping!
3 x Thorlabs SM2RC clamp. $29 each.
3 x Generic brand QR clamps, from Amazon. $7 each.
1 x Generic QR plate, from Amazon. $10.
1 x Newport focusing Lens Tube, 2 inch diameter, MODEL: LT20-F, $52.
This newport tube is really useful and does not change the rigidity of the set-up. I use this variable tube to dial in infinity with a tube lens and to set exact magnification when working with bellows lenses or finite objectives.
Notes: I own a couple of 52mm tubes, OD 54mm, that fit the Thorlabs SM2RC clamps but, unfortunately I do not know the manufacturer. I found these on Ebay, so keep a look out, and if you find more, please let me know.
Thorlabs male 2.035-40 threads are compatible with female 52mm x 0.75 threads but male 52mm threads will not thread into the female 2.035-40 Thorlabs threads.
SM2RC clamp at Thorlabs: https://www.thorlabs.com/thorproduct.cfm?partnumber=SM2RC
Newport focusing Lens Tube, LT20-F: https://www.newport.com/p/LT20-F