Which is sharper - 17-55 IS or Sigma 50 1.4?

I'm thinking about getting a Sigma 50 1.4 for taking low light indoor shots. I'm already used to getting super sharp images with my 17-55 2.8 IS. Is the Sigma 50 going to be as sharp at 1.4 as my 17-55 is at 2.8?

I've never shot the 17-55 IS, but I can tell you that a working copy of the Sigma 50mm f/1.4 is plenty sharp at f/1.4. That being said, I believe it is a lot easier to create a lens that is sharp at f/2.8 than it is to build a lens with corresponding FL that is just as sharp at f/1.4...

I didn't do any test. My guess is pretty much the same sharpness when you stop down your sigma 50/1.4 to f/2.8. I can test with my brother's sigma 50/1.4 this weekend. I had done a test with the canon 50/1.4 vs. 17-55 at f/2.8 (FL 50mm). I would call it equally sharp or if I have to pick, the17-55 might be a tiny little bit sharper.

With a good copy - the Sigma is very sharp @2.8 - rivaling the 17-55mm, IMO.

hieu1004 wrote in post #11227354
With a good copy - the Sigma is very sharp wide open - rivaling the 17-55mm, IMO.

I believe so. I meant if they are both set at 2.8

IMO no way is the Sigma (and I've had more than a few) as sharp wide open as the 17-55 is at 2.8... now the Sigma at f2 that's a different story. It get's very sharp from f2 up.

I have no idea about the Siggy 50, but the 17-55IS is a tough act to follow. I shot an indoor event last night with my new 17-55. It is an amazing lens.

nonick wrote in post #11227691
I believe so. I meant if they are both set at 2.8

Oops - yeah, this is what I meant - if they were both at 2.8. Wide open on the Sigma is still acceptably sharp, but it gets much much sharper if stopped down a couple.

i have used/owned both, sigma 50 1.4 is sharper

I've never even seen a Sigma 50 mm, but own the 17-55. I've read the Photozone reveiw of the Sigma, and it's quite impressive - it's results surpass the 17-55 which is quite remarkable. Hat's off to Sigma - it wasn't many years ago that Sigma was another term for paper weight.

Having said that, sharpness is wonderful if it's really needed other than in pixel peeping. In real life where one doesn't zoom in at 4:1, the difference is more of an academic exercise.

The 17-55 has its own advantage - it's not stuck at one focal length.

In any event, comparing these lenses doesn't seem to me to make a lot of sense, as they serve very different purposes.

Glenn

I dont own the signa but I do own both the Canon 50mm 1.4 and 17-55mm 2.8 and from I see that at 2.8 for both, I see about no difference in sharpness. Both razor sharp, and I imagine would be about the same on the Sigma as well.

eaglefan wrote in post #11226693
. Is the Sigma 50 going to be as sharp at 1.4 as my 17-55 is at 2.8?

Note the OP's question - extract above - was not just whether the Sigma was sharper, but whether it was as sharp at 1.4 as the 17-55 is at 2.8.....

The answer to the OP's question is no. And the CA from the Sigma really causes grief as compared to the Canon shot.

Example from a Sigma-calibrated lens, micro-adjusted to the Canon, probably about as good as it would get? Not bad though considering that lens is at f1.4!

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