Shooting wide open on fast lenses??

[cap10kirk]

I'm trying to get a handle on the technical side of shooting. I've ordered my Rebel T2i. Since I'm on a limited budget, I'm planing to get the Canon EF 1.8/50mm (niffty 50, great term), and some old Nikkor AI primes. There are some really fast primes(f1.2 & f1.4) that I'm looking at.

Shooting wide open at f1.2 or f1.4, wouldn't the dof be extremely shallow, where it would be impossible to shoot a moving subject? Also, if you shoot a subject at f5.6 on a Canon EF 1.4 and a Canon EF 1.8, would the image be the same? Everything being equal. Thanks.

[Barry_Green]

1. Yes.
2. As for sharpness, yes (at least in motion). I don't know those lenses to know whether one would deliver a better shot in stills vs. the other, but in video, they'll be equally sharp. Don't know if one delivers better contrast than the other.

[cap10kirk]

1. Yes.

Thanks again. I apologize for being such a noob, but if my focus is on video and not stills, do I need to purchase a lens faster than a f2.8?

[Barry_Green]

If you want the shallow-DOF look that comes from a more-wide-open aperture, or you want the extreme low-light performance that comes from a faster lens, then yes. If you like the look of the DOF at f/2.8, and it gives you adequate performance in low light conditions, then no.