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Canon pixel size for 5D is 5616 pixels across 36mm so 6.4 microns per pixel, 5616 x 3744 format.
Powershot G6 is 2.3 microns per pixel, format is 3072x2304. 35-140 equivalent focal length. Threads are 58mm. Should be able to adjust zoom to get what we want. Lens is f/2-ish. But one quarter the number of pixels compared to 5D mark II.
Did a 5D test with 135mm lens and 100 l/mm grating, and it seems to work really well! Using 820 nm IR long pass gives a NIR spectrum that spans a few hundred pixels. Dispersion is about 1nm/pixel so that ought to work quite well for water vapor. The wider-field alternative, that might have comparable flux due to blaze on the grating, would be 300 l/mm in tandem with 85 mm lens.
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