Lenses

Build quality
Optical quality
Value for money
Overall

Cons: Its a slow lens; to get the best out of it, a tripod is needed unless in very good outdoor light. The design of the lens shade and sleeved cap means that after a few weeks use, the paint on the outside of the lens shade is getting marked.

Pros: Spectacularly wide angle of view Very sharp stopped down. Relatively low distortion for a lens of this type

Summary: I've been using my 12 -24 for 4 months with a Canon 5D mk 2; a camera which will show up the weakness in any lens. It’s a specialist optic, not a general propose lens; so not only is it unique, it needs skill to get the best out of it. The extreme perspective at 12mm is what drew me to this lens and its giving spectacular results. Like the previous 12-24 mk1 (which I still own), it needs to be stopped down to get the best results. At F8 to F11 its sharp; even at the edges at 12mm. At f 5.6 at 12mm it’s a soft at the edges but sharp at the centre. At F10 or F16 it performs much better at the edges than I would have expected. If I want to pixel peep at 200% then I can see a hint of colour fringing at 12mm; I’n practice its never likely to be noticeable. As I don’t shoot grey cards I can only say that vignetting is not a significant problem (as it is on my L series 24-105). Again Lens flare has not been a major problem; however there have been a few occasions where I have had to shield the lens with a book or my hand. Anyone experienced with an ultra wide should not expect anything else if shooting towards the sun. Distortion at 12mm can be a distraction; but at 15mm, barrel distortion is negligible and this is still ultra wide for FF. I compared the results at 24mm with my Canon 24-105 and I would say without doubt that the Sigma is just as sharp in practice and is more usable as there is virtually no linear distortion at all. Autofocus is fine and silent; however with a lens of this type it will invariably focus at the long end of a room so if you have anything close at wide aperture you may lose focus. I focus manually for critical work. Conclusion It’s the only wide-angle lens that I have owned (with the exception of Sigma’s DX 8-16) that is not used at the extremities very often. From 15mm to 24mm it’s a great lens for architectural photography. From 12 -15 it’s a wide-angle monster which could easily get out of control in the wrong or experienced hands.

Build quality
Optical quality
Value for money
Overall

Cons: Not excellent sharpness in the corners, He suffers a lot flare in backlight

Pros: Angle of awesome on FF, Building Strength, distortion, overall optical yield, reduced vignetting

Summary: AWESOME WIDE ANGLE LENS ... must buy !!!

Build quality
Optical quality
Value for money
Overall

Cons: Above reviewer does not have this lens.

Pros: It should be better than this.

Summary: This is a new lens, not out yet.

Build quality
Optical quality
Value for money
Overall

Cons: Flare Soft in viewfinder, hard to focus.

Pros: 12mm fullframe Special lens Video usage

Summary: It 's not an easy lens. Good results when you know how to work with it.