This popped up in the horsehead thread, but I thought I'd make a separate thread here.
The discussion was around how people's eyes have different sensitivities at different frequencies. Some people are more sensitive in the area where red starts heading towards the infra-red which is where a lot of emission nebula emit their light. TBH, I'm still a little foggy on what causes this variability in terms of physiology but it got me thinking - would it be possible to create an experiment to measure such frequency dependent sensitivity?
Presumably, all one would need is a standardised broadband light source and a range of filters, perhaps red, Ha, S2, maybe Hb too.
If the light source were baffled such that the only light emitted was through the filter, one could set it a standard distance away from a (standardised) white card in a dark room and by turning the light on and off one could determine detection at those frequencies.
The biggest issue I see is the procurement of a standardised broadband light source as a light source will have its own emission curve.
An alternative would be to buy some near infra-red LEDs such as
these ones, available in wavelengths from 670 to 1650nm. That may be simpler to control. What are your thoughts?
Markus