Sigma 30mm f1.4 vs. Canon 28mm f2.8

[Henrik Ploug]

Here are some test shots from the Sigma 30mm f1,4 and the Canon 28mm f2,8. None of the shots have been sharpened in camera or in Photoshop.


The Sigma is sharper in the center and the Canon is sharper in the corner, when compared at equal apartures.
The center sharpness of the Sigma at f1,4 can be compared with the center sharpness of the Canon at f4. The corner sharpness of the Canon at f4 can be compared to the Sigma at 5,6.

[Henrik Ploug]

Here are some test shots from the Sigma 30mm f1,4 and the Canon 28mm f2,8. None of the shots have been sharpened in camera or in Photoshop.


The Sigma is sharper in the center and the Canon is sharper in the corner, when compared at equal apartures.

The center sharpness of the Sigma at f1,4 can be compared with the center sharpness of the Canon at f4. The corner sharpness of the Canon at f4 can be compared to the Sigma at 5,6.

[Lenny_D]

Really interesting.... What do you think, is the large change in sharpness across the diameter of the Sigma lens disturbing in real life photography? Is the 1.5 stop worth the unbalance in sharpness?
Obviously the Canon gives a more balanced picture (regarding sharpness).
Any other differences, e.g. contrast, clarity?
I'm still looking for the best "standard"' prime on a 20D.

Lenny

[Henrik Ploug]

I have just done the test today, and I haven't noticed the soft edges before now. After I noticed, I have now expanded the test, so that it also includes edge crops:

[Henrik Ploug]

At the edge both lenses seem quite sharp, and I think I will keep the Sigma and sell the Canon. Just have to avoid getting the motif stuck in the corner.

[Hellashot]

The Sigma 30mm f1.4 DC is known to be a very sharp lens at f1.4, a lot sharper than Canon's f1.4 50mm.

[grego]

That's the 28 f/2.8, not 50.

[Hellashot]

Originally Posted by grego

That's the 28 f/2.8, not 50.

Yes, what I stated is what I wanted to say.

[grego]

Originally Posted by Hellashot

Yes, what I stated is what I wanted to say.

I gotcha. I do have to say the 50 1.4 is one of the sharpest lens out there. And it not being an L, makes it even better of a deal. Although I haven't seen a side by side comparision of the 50 vrs 30 1.4's.

[Henrik Ploug]

Just added some extra shots from the edges and the top left corner. My conclusion:

The Sigma 30mm f1,4 is sharpest in the center.
The Canon 28mm f2,8 is sharpest in the corner.
The two lenses are just about equal at the edges.

[pfogle]

Nice example - the Sigma looks good compared to the 28/2.8 - though to be honest, I'm selling the EF28/2.8 because it's just not a great lens.

Has anyone compared the Sigma to the EF 28/1.8 - also not known as a great lens, but much more interesting to me than the f2.8 version.

thanks
Phil

[drisley]

If you get a good copy of the 28/1.8, it's an amazing lens.
The build and autofocus (speed and silence) are both fantastic.
I had a great copy that I sold to RichardTheSane, and he will vouch for it's optical quality.

[Andy_T]

That might have something to do with the Sigma being a DG lens (for reduced image circle) versus the Canon being a lens for full frame ... so you don't really see the edges of the Canon lens on an image from a 1.6 crop camera.

f/1.4 vs. f/4.0 is a difference of 3 full stops, btw. (that means 8 times the light gets in at the same time)
Full stops are 1.0 - 1.4 - 2.0 - 2.8 - 4.0 - 5.6 - 8.0 ...
Maybe not so important for landscapes, where you'd stop down anyway, but quite important if you want to isolate your subject.

Best regards,
Andy

[pfogle]

thanks, dr - by the way, do you know what the odds are on a 'good copy'? I'd put Sigma's at about 1 in 4 being good for the wides, but Canon I have no idea about. I haven't had a 'bad' Canon yet, but you do hear about them, especially with the 28/1.8 and the 20/2.8 for some reason.

Phil

[Wavy C]

Tnx for posting these test results Henrik. Very well laid out and makes it easy to compare.