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We have a Nikon TS100 Microscope (https://www.nikoninstruments.com/Products/Inverted-Microscopes/Eclipse-TS100) with a camera trinocular - it's designed to be used with a C-mount and a C-mount camera, but it would save everyone a lot of time and money if we could use it with a DSLR we use with the neighboring Zeiss microscope.

Is there a reliable way to attach a DSLR to the fitting for a C-mount? (or to the C-mount aperature?)

Rudimentary web searching shows adapters like these: http://www.edmundoptics.com/microscopy/relay-lenses-couplers/c-mount-camera-lens-adapters/1459/

But it's a little unclear to me that this is what I'm actually looking for, the page says

By popular demand, Edmund Optics carries 35mm SLR (Single Lens Reflex) camera lens c-mount adapters for standard C-mount video cameras. External C-thread at one end of the c-mount adapter fits most standard industrial video cameras. The other end of the c-mount adapter accepts camera lenses.

It sounds like I might not be able to attach this adapter to a C-mount already affixed to the microscope.

Any suggestions?

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2 Answers 2

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The adapter you listed is made for doing the opposite of what you wish to do: It is made for using C-mount cameras with DSLR lenses.

There are a couple of issue with doing what you want that make it problematic:

  • The C-mount registration distance (a/k/a flange focal distance a/k/a distance from the film/sensor to the lens mounting flange) is 17.526mm. The registration distance for most DSLRs is around 42-47mm. That means an adapter would need to have a negative thickness to use a DSLR on a C-mount lens or microscope. Since that is physically impossible, any such adapter would need additional optical elements to correct for the disparity in registration distance and a correction for that large of a difference would be severely detrimental to image quality.
  • The image circle projected by a C-mount lens is anywhere from 5mm to 22mm wide, depending on the particular format for which it is intended. Systems that use C-mount connectors range from 8mm and 16mm movie cameras to 1/3", 1/2", 2/3", 1", and 4/3" video formats. (For more on the ramifications of this, please see this wikipedia article for C mount.) Even at the largest, 22mm is only about half the length of a 35mm film frame diagonal. That means that at best you can only use the center one-fourth or so of your FF DSLR's pixels when connected to a C-mount coupler without introducing additional optical elements to expand the image circle. Just like using a teleconverter with a DSLR, this would introduce additional optical aberrations and spread the light thinner. A 2X teleconverter makes a lens two stops slower, or one-fourth as bright, than the same lens without the TC.
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  • \$\begingroup\$ That's vastly more helpful than the guy at Nikon who just said it "couldn't be done" rather than the reasons why it wasn't done more often. Thank you! \$\endgroup\$
    – Esteve
    May 6, 2016 at 15:19
  • \$\begingroup\$ All this only means that you need an adapter with optics like the one Linda Blair pointed to. \$\endgroup\$
    – Caleb
    May 18, 2016 at 20:50
  • \$\begingroup\$ @Caleb In which case the last sentence of the first bullet point and the last two sentences of the second bullet point are applicable. \$\endgroup\$
    – Michael C
    May 19, 2016 at 0:12
  • \$\begingroup\$ Who's Linda Blair? \$\endgroup\$
    – Esteve
    May 19, 2016 at 20:15
  • \$\begingroup\$ @Esteve That answer was deleted by the moderators. \$\endgroup\$
    – Michael C
    May 20, 2016 at 13:12
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If the camera you have is a Nikon then a search for "c mount to nikon f" would turn up something that ought to let you attach the camera to the microscope. If not Nikon then substitute manufacturer & lens mount type as necessary...

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  • \$\begingroup\$ A search does turn up 3rd party adapters like this one: amscope.com/… However, I'm a little dubious... \$\endgroup\$
    – Esteve
    May 6, 2016 at 17:55
  • \$\begingroup\$ That's the same thing I found and it looks to me like its exactly what you're looking for when comparing the illustrations in the microscope brochure with the image of the adapter. \$\endgroup\$
    – KarlC
    May 6, 2016 at 22:36
  • \$\begingroup\$ Yes, but first, the C-mount has threading and the web pictures of the adapter show no threading, which makes me worry about support. Second, it doesn't address the issues raised by Michael Clark in his answer. \$\endgroup\$
    – Esteve
    May 9, 2016 at 16:57
  • \$\begingroup\$ All the adapter needs to do is fit snugly into the opening provided for it. Measure the diameter of the opening & see how close it comes to the stated diameters of the adapter rings. Gravity will ensure its stability. The adapter does appear to have its own internal optical elements which should project an image circle that fits within the dimensions of the image sensor. For what it costs it doesn't seem like much of a risk to take by getting it & trying it out. If the results aren't to your satisfaction you can always return the thing. \$\endgroup\$
    – KarlC
    May 10, 2016 at 0:58

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