[Klaus]

Nice but not without issues:

[url="http://www.opticallimits.com/canon_eos_ff/676-sigma1224f4556iiff"]http://www.opticallimits.com/canon_eos_ff/676-sigma1224f4556iiff[/url]

[boren]

An interesting review of a very attractive lens, one of the few Sigma lenses which may some day make me overlook the company's compatibility issues.



One things that's a bit odd is the increased distortion at 12mm. If I recall, the previous version of this lens had very low distortion, even at this extreme focal length. Are you aware of any changes in the optical formula which may have resulted in this regression?

[Klaus]

[quote name='boren' timestamp='1315080835' post='11279']

An interesting review of a very attractive lens, one of the few Sigma lenses which may some day make me overlook the company's compatibility issues.



One things that's a bit odd is the increased distortion at 12mm. If I recall, the previous version of this lens had very low distortion, even at this extreme focal length. Are you aware of any changes in the optical formula which may have resulted in this regression?

[/quote]



Well, it is a different design. There's one new element and a new group and it's nearly 2cm longer.

[Brightcolours]

Old lens:





New lens:





A totally different design, basically.

[Yakim]

5 stars on Price/Performance? Why? After all, the most coveted aspect of this lens is its 12mm ability and there, the actual border resolution figures as seen in the Field Curvature section is very poor.



The chart below assumes a "flat wall" scenario where the center is set to the optimum focus distance - imaging that you stay in front of a flat building and simply use the camera's AF. May I guess that many users will use it exactly like this?

[Klaus]

[quote name='Yakim' timestamp='1315124630' post='11288']

5 stars on Price/Performance? Why? After all, the most coveted aspect of this lens is its 12mm ability and there, the actual border resolution figures as seen in the Field Curvature section is very poor.



The chart below assumes a "flat wall" scenario where the center is set to the optimum focus distance - imaging that you stay in front of a flat building and simply use the camera's AF. May I guess that many users will use it exactly like this?

[/quote]





If a lens offers something that is not provided by any other one it is almost a 5* lens by definition in my book.



We were criticized for not providing any hard guidance on field curvature - now we do.

[Yakim]

Well, the 8-15 also offers something that is not provided by any other and it still got "only" 4 stars for Price/Performance.

[Klaus]

[quote name='Yakim' timestamp='1315125889' post='11291']

Well, the 8-15 also offers something that is not provided by any other and it still got "only" 4 stars for Price/Performance.

[/quote]





There are circular and full frame fish-eye lenses out there. The Canon is unique because it combines them.

The Sigma is unique because there is no other 12mm rectilinear SLR lens AT ALL.

[Yakim]

I agree with that and understand your PoV but I still don't feel comfortable with the highest rating.

[frank]

Is it significantly better than the previous version?