Would a flash help at this?

[Village Idiot]

You cannot say it globally like like that. He doesn't have a 1.8, but a 1.4 (which I see you missed reading), which is even faster than your 1.8 and it was still quite dark. Obviously some bars are darker than others.

And not everyone wants to look at pictures of a person's shoulder in focus and everything else not because of alwasy using such a shallow DOF.

Even f/2.8 is pushing it a bit.

 

[JerryPH]

Off camera flash to the rescue!

As far as if F/2.8 is pushing it... its close, but it will depend a lot on his focal distance. An F/5.6 at 200mm will give you as much as or more DOFas an F/2.8 at 35mm.

 

[RyanLilly]

But here's the problem. He was probably shooting at f/1.4 just to get a fast enough shutter speed. The DOF is so shallow that it's going to be nearly impossible to focus on a point manually on a subject that's moving. But if that lens is anything like the f/1.8, then it sucks at focusing in the dark.

Well the 1.4 is actually much better at focusing in low light, but I will agree manual focusing is really not viable in this situation, especially considering the small viewfinder and crappy focusing screen(or lack there of).

I have taken some really nice shots in similar bar situations. The key is to use only the center AF-point and focus on the subjects eyes than recompose. The photos posted looked like just a snapshot, but with such limited DOF, the focus and recompose is really a must on every shot. Just keep in mind that only that persons face, maybe not even their whole face, and anything on that same plane will be the only thing in focus.