[Aavso-photometry] Calculating flux from raw adu's?

[mlfleenor at charter.net]

While this is not directly related to photometry of stars I am hoping someone can point me in the right direction or give helpful insight regarding a terrestrial project.

I have a standard NIr source that I would like to use to determine the flux of an object that emits in the NIr. I have a passband filter for the region of interest. 

Suppose I make a measurement of the standard and the object and use a 250 pixel  area for the selection "aperture" in Maxim DL- can I simply relate the two by measuring the raw adu's of each and relating the two as a ratio? There are no extinction concerns and the source and sample are of the same color. 

I am using an ST10XME with a 4" apochromatic objective. The sample will be ~5 meters away.

Please clue me in if I am making a big conceptual error :)

Thanks,

Mike