Aperture, Iso light deficiency conditions

Hello doctor,

Let me ask are in conditions of lack of light should prioritize increased export or increase the iso?


According to my own wedding photography contract opinion itself will pros doing the following steps. Large open password (how big the opening then depends on the aperture of the lens is the largest open and want to thin DOF more or less)--> giãm speed to the point that safe enough to shoot without shaking hands (ex: 1/60, 1/30)--bright clearing > EV-battery-> register light deficiency increases iso. rong usually increase the ISO is the last dose. Because of increased ISO also means making more Noise with photos.

I take something new is the problem
If the shooting scene

Buy 28 f2 f2 open nuts at infinity
35 1.4 1.4 opening nuts at infinity
50 1.2 1.2 open nuts at infinity

strokes off
iso, depending on the person, there's like 200, there's like 400 ... somebody likes to 3200;))