Lots of folks have talked about doing a higher-end spectrometer attachment based on an SLR lens mount. This is a good idea -- we can model it and share the model on Shapeways so people can 3D print it.
To start out with, I did a quick survey of open source Thingiverse models of camera lens mounts and lens caps:
One thing I'm not sure about -- will take some testing -- is whether we want to make an attachment for the front of a lens -- lens-cap style -- or to attach directly to the body of the camera, which would have no lens. I'm not sure the latter would work with our current spectrometer design... the geometry may be pretty different. I also don't have an SLR :-P
@BKF11 - calibration works super well with our current setup; it's sub-nanometer. The big problem with an SLR (besides expense) is that they don't have a USB interface, so it ends up being cumbersome to record and analyze data.
@hank - do you have any 3d models or even just really good measurements for those? The screw threading in particular...
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Not sure what is mounted to what in the 3D image above, but the two camera mounting methods are different: 1) "in convergent beam" - grating parallel to image chip w/o lens and 2) "objective grating" - grating parallel to front of lens. #1 avoids the lens (spectrum limits) but causes blurring as the focus changes across the spectrum (i.e. across the imager chip). #2 has a smaller aperture plus glass in the path but the spectrum is in focus.
However, in either case you have to include the slit in the design. These SLR methods are most often used for astronomy where true collimated light from a star, off-axis to the grating+lens, is the source. With light-bulbs and such, a precision slit at the end of a dark tube (zero reflections) with the lens focused on the slit, would be required. Depending on the lens, this suggests a more elaborate design to house slit, grating and lens adaptor. Finally, note that the grating must be adjustable to keep its orientation aligned with the imager chip. Could be two parts (lens+grating) and (tube+slit) but they need to be light tight and aligned (slit with grating and grating with chip).
Hope this is helpful. Cheers,