Using Aperture to find flux

Posted by CassCrowe on Nov 15, 2016; 4:36pm
URL: http://astroimagej.170.s1.nabble.com/Using-Aperture-to-find-flux-tp532.html

So I'm trying to get the H-alpha flux of a nebula and when I use the aperture tool a circle with T1=somebignumber next to it. Is this the flux? If so this gives me a magnitude of about -30 which doesn't seem right. Any help?