This is kind of a far out there question but it is puzzling me. How to find really faint star magnitudes where the magnitude more or less represents mag of our own eyes perception limits (a sort of human luma curve adjusted value).

I am often trying to note in the field the dimmest field star seen when I look for faint targets to be a sort of limiting mag through the eyepiece with my trusty 7mmNag. Often I can only find such star data in Aladin using the 2MASS data. Problem is the Jmag and Hmag numbers seem 4 mag 'brighter' than I suspect these stars are. Example: For Minkowski 2-9 I noted an obvious field star NW of central star by about 1'. MegaStar say Mag 16, simbad in Aladin says B mag is 15.2 and R mag is 14.5. Then the 2MASS mags are even more confusing with Jmag 12.47 and Hmag 11.94.

My dimmest seen star was due east of central stellar point by about 1' and only has 2MASS Jmag 14.53 and Hmag 13.87

So should I say that mag is [MegaStarMag of Brighter Star] + [12.47 - 14.53] or in this case 16 + 2.06 or 18? or maybe stick with Blue mag for 15.2 + 2.06 for 17.26 (more believable). I would be basically lowering mag by the difference in Jmag values.

If there were a direct mag number in some huge catalogs like 2MASS that gave a 'human visually perceptable mag' that would be nice.