On Mar 15, 2016, at 11:04 AM, Roger Breton <graxx@videotron.ca> wrote:

I have an old visible range Bauch&Lomb monochromator with a 1mm exist slit. If I was to take a picture of the slit with my camera, at some reasonable interval, could that be a crude way to get to my camera's response?

As Iliah notes, you'd need an independent measurement of the brightness of the sample. And monochromators can be pretty dim, too, which can cause other problems. However...you can also use the monochromator to determine the transmission efficiency of the cheap diffraction grating film that's easiest to work with to make your own large spectroscope. You'd set things up such that a camera had a view of both the output of the monochromator and said output diffracted, and compare the two values. That's an one-time measurement (well...lots of measurements across the spectrum) which should be valid at least for that batch of diffraction grating if not all such manufactured with the same specifications. The spectroscope, of course, also requires an independent measurement. But that you can get from an ambient measurement of the illuminant (using an i1 Pro or the like) at the entrance to the spectroscope. And you get all your data from two exposures: one with something spiky (like a cheap compact fluorescent bulb) for spectral calibration, and the other from something smooth (incandescent) for your data. b&