First Look: Sigma 20mm f/1.4 DG Art from LensRentals.com

[TWI by Dustin Abbott]

Sigma is an interesting company. If they could just make the autofocus more reliable, I would be more interested. Price is not a big deal when the lens has focus that I can not trust. YMMV

Yet various tamron and manual focuses lenses have found their way into your bag.

No they have not. I own only Canon lenses because third party lenses do not perform well enough. Which was my point.

I think that may have been directed at me. I had quoted you and +1'd your post and they saw my signature.

On that note, two things. Yes, I own three (soon to be four) Tamron lenses. My three that I've regularly used (24-70, 70-200, and 15-30) have been deadly accurate for me. I can trust them, so they've gotten heavy usage in my bag.

The second thing is a bit ironic and addresses the MF glass in my kit. Wide aperture AF lenses are sometimes a challenge for people. Outer points aren't as reliable, and focus/recompose in some cases can subtly alter focus. The irony is that the wider the aperture the easier it is to visually confirm focus when using an EG-S focus screen or something similar. You don't worry about AF points - just compose how you want and fire away when you nail focus. I actually have a really high keeper rate with MF wide aperture glass WITH an EG-S, but on my bodies without it my keeper rate drops a lot.

 

[Ladislav]

Sigma is an interesting company. If they could just make the autofocus more reliable, I would be more interested. Price is not a big deal when the lens has focus that I can not trust. YMMV

Yet various tamron and manual focuses lenses have found their way into your bag.

No they have not. I own only Canon lenses because third party lenses do not perform well enough. Which was my point.

I think that may have been directed at me. I had quoted you and +1'd your post and they saw my signature.

On that note, two things. Yes, I own three (soon to be four) Tamron lenses. My three that I've regularly used (24-70, 70-200, and 15-30) have been deadly accurate for me. I can trust them, so they've gotten heavy usage in my bag.

The second thing is a bit ironic and addresses the MF glass in my kit. Wide aperture AF lenses are sometimes a challenge for people. Outer points aren't as reliable, and focus/recompose in some cases can subtly alter focus. The irony is that the wider the aperture the easier it is to visually confirm focus when using an EG-S focus screen or something similar. You don't worry about AF points - just compose how you want and fire away when you nail focus. I actually have a really high keeper rate with MF wide aperture glass WITH an EG-S, but on my bodies without it my keeper rate drops a lot.

I actually own Tamron 24-70 VC. I bought it after reading your spectacular review. It is good value for money - especially now after price drop BUT - I have a second copy and I definitely don't have the same experience with AF and VC as described in all your Tamron reviews. AF is reliable only for stills and VC is 2 stops max for me (my first copy was mostly 1+ stop). So its either because of my inferior technique or because of significant variance among different copies of Tamron lenses. Since this lens, I'm going Canon only and I wasn't disappointed again.

 

[Pitbullo]

Sigma is an interesting company. If they could just make the autofocus more reliable, I would be more interested. Price is not a big deal when the lens has focus that I can not trust. YMMV

I don't think its possible. Canon has a big advantage, and cameras include data about each Canon lens that makes AF more reliable. Canon may have some data about third party lenses in the cameras, but it obviously is not helping third party autofocus.

...

I know my Canon lenses are way more accurate than my Sigmas, thoug a little work with the Dock worked wonders for my 35mm ART. Since I use an old Canon camera body (550D), would that make new Canon lenses less accurate for focusing, since my camera does not get firmware updates (and info about new lenses)? I just wonder how that works, as I do suspect that those lens data included in camera is primarely for corrections, not for focusing.