[toni-a]

My point was: You ignored the ISO variable, which equalizes it all even with flash photography.

 

BC, I understand your point, that with larger sensor comes lower sensor noise and thus I have the same effect at higher ISO.

 

However sensors are evolving and I don't know for how long full frame will have a large advantage over APS-C, what you are saying is true for 5D vs 30D but there's none of it when I am with my usual combo 5D vs 750D, I known we are comparing sensors that are ages apart, but things are evolving, and they are evolving very fast.

 

So with the very decent high ISO performance of modern sensors even smaller ones large apertures still make sense, on my 300D ISO 400 was quite noisy, on my 750D I can barely see any difference. SO the ISO advantage of full frame is having less and less importance as long as we are in the usual range (below ISO 1600), all modern DSLRs have a decent performance.

So does it still make sense having fast glass on small sensors, I think yes