Taken with an unmodified Canon 50D which has a stock internal filter. The cutoff is at 420nm in the blue so that the 405nm mercury line isn't recorded. Self described text. Corrected data. Many more lines & even continua are visible with the eye. The camera can't handle the contrast, or at least the brightest lines are left w/pleasing color & contrast
I deleted & replaced the pic w/corrected data. Sorry but your comment got deleted as well. What you said was that the upper CMH spectrum is different from what you normally know. I agree, perhaps because the 250w M58/H37 ballast did not power the lamp properly as indicated by the sodium self absorption at D-line resonance. If you look at THIS spectrum, the D-line is well self absorbed like HPS lamps. There are also other emission lines that don't match.
If only the title and descreption was needed to be corrected, you could simply edit your picture instead of deleting and reuploading. Only if the text in the picutre itself is wrong, this reuploading is necessary.
Anyway, the upper spectrum looks indeed like an underdriven MH lamp, though in 4000K color CMH lamps, the D line isn't self absorbed like the HPS lamp. This accurs usually on warm white CMH lamps, where there are more sodium.
Indeed, i surprised when i saw the first spectrum of CMH with my simple CD-R, because this was the first MH lamp with a sodium D line in the same length of re-absorption as the HPS.
If you have an account in LG, you can see my spectra gallery that i photographed with my camera and my CD-R.
Login
What was bad with my comment!?
Anyway, the upper spectrum looks indeed like an underdriven MH lamp, though in 4000K color CMH lamps, the D line isn't self absorbed like the HPS lamp. This accurs usually on warm white CMH lamps, where there are more sodium.
Indeed, i surprised when i saw the first spectrum of CMH with my simple CD-R, because this was the first MH lamp with a sodium D line in the same length of re-absorption as the HPS.
If you have an account in LG, you can see my spectra gallery that i photographed with my camera and my CD-R.