Wide Angle Sigmas: 12-24 vs 10-20 angle of view?

[ewhip17]

With the "angle of view" on the 12-24 being 122 degrees at the wide end(Sigma stats) compared to 106 degrees (if I remember correctly) on the 10-20, wouldn't that make the 12-24 a "wider" wide angle lens even though it gives up 2mm? Or am I thinking about this incorrectly? Which one actually takes in more territory? Would the 12-24 also be inherently sharper and have less distortion? Ignore price for a moment on these - I realize the 12-24 is more expensive.

Thanks in advance for your thoughts and expertise!

 

[Big Mike]

I believe the 12-24mm is designed for 35mm film or full frame digital cameras, so it needs a wider 'Field of View' to cover the larger surface of the film/sensor.

The 10-20mm, I believe, is only for 'crop' bodies, and therefore doesn't need such a wide FOV.

If you put both lenses on a crop body, the FOV would be pretty close. Well, reasonably close anyway. 12mm is, after all, 20% more than 10mm.

So to sum up, yes...the 12-24 does technically take in more territory but that only does you any good if you are using a 35mm film or full frame digital SLR. That's also why it's more expensive.

 

[ewhip17]

interesting - makes sense I guess when you look at the fact that one is part of the "DG" line and one is part of the "DC" line