How big of an upgrade would these be?

I have a 7d and the Canon f/1.8 versions of the 50mm and 85mm. I like to shoot with as wide an aperture as possible when outside. Would the Sigma 50 and 85 f/1.4 be considered a significant upgrade in quality over the Canons?

I will use a variable neutral density filter when possible outdoors on those lens as well.

Or should I keep the primes I already have and go with the Sigma 30mm f/1.4 and Canon 135 f/2?

I would say it wouldn't be much of an upgrade. Spend the money on trading up to full frame, and the lenses you already have will be used to their full potential.

If you desire is extreme shallow DoF I agree, you probably ought to go FF. The FoV and DoF of your 85 F/1.8 on FF will be like a 50 F/1.1 on your 7D. Or another way of looking at it, an F/2.8 zoom on FF will give the same DoF as an F/1.8 prime on your 7D (assuming same FoV).

I would like to keep the 7D because I don't just use it for portraits but College wrestling as well. Otherwise I wouldn't mind buying a 5D MII or 1DS MII. There are other options of course but I would like some opinions so if anyone else has anything to add that's owned any of these lens I would like to hear it.

I don't think you would gain a great deal, I own the Sigma 85/1.4 and it is my favourite lens on a crop by a mile (mainly because it's the equivelant of 135mm f/2 on a FF).

Sticking to the crop for the moment you would lose around 20% DOF moving from f/1.8 to f/1.4 on the 85mm, that may sound a lot but it isn't. With a subject distance of approx 15ft (4.5m) at f/1.8 your DOF is approx 7.5 inches (19cm). If you open up to f/1.4 your DOF would be approx 6 inches (15cm). To be honest I often have to step down to f/1.6-1.8 to get enough DOF, also f/1.4 on the 85 is a bit soft.

On the 50mm you would lose the same 20% DOF, in the above example the DOF would go from 22 inches (56cm) to 17.5 inches (44.5).

Obviously the closer you get to your subject the shorter your DOF will be and vice versa.

At the same focal lenght on a FF you won't gain anything if you want the same focal distance. Sigma 85 f/1.4 is almost identical in focal distance and DOF to a Canon 135L f/2 on a FF and I'm not aware of any faster 135mm lenses. Sticking to the above example you could put a Sigma 85/1.4 on a FF, to the same magnification you would have to move closer to your subject from 15ft (4.5m) to 9ft (2.7m), compared to it on the crop your Field of View would increase from 14.5 degrees to 23.5 degrees but your DOF would decrease from 6 inches (15cm) on the crop at 15ft, to 2 inches (5cm) on the FF at 9ft.

That was a bit complicated for 5:30am, I'm waiting to go out shooting and I'd better start packing my bags.

full frame vs new lens,

I pick full frame, if i was in your situation.

They will only be an upgrade if they decided to focus well out of the box....which sadly is a hard thing for them to do.

thestone11 wrote in post #13923020
They will only be an upgrade if they decided to focus well out of the box....which sadly is a hard thing for them to do.

Well it is not a hard thing for them to do. You are implying majority of what Sigma corporation is selling/producing is defected. If that is the case, I doubt the corporation would have existed this long.
Most of them focus well out of box, it is indeed unfortunate that it didn't happen to you when you made your purchase.

that little extra speed isnt worth the lose in quality.. If you really want the 1.4's get the canons.

I've heard of the Sigma focusing issues, but haven't experienced them myself. The Sigma 50mm f/1.4 has a much smoother out-of-focus area but it is pricier than the Canon. If you're using your f/1.8's outside, though, are you finding it difficult to no over-expose? I've thrown an ND filter on before to shoot at f/1.4 while outside otherwise, it was way too bright, even at ISO60.

Thanks for the responses everyone and I have decided to pick up the 135L to complement the 50 and 85 I already have. Rather than go with the Sigma 30mm I think I may buy the Sigma 17-50 f/2.8 for a little more versatility in the large family shots.