Pro/Cons for Sigma 12-24 II & Canon 16-35 II

vvv14 wrote:

Robert, thanks for your reply.

I own both the Canon 17-40 and the Sigma 12-24 Mk II.

Am I correct to assume you acquired the Canon prior to Sigma? You plan on keeping both?

I will be keeping both.  Not sure which I had first as I previously owned a Sigma 12-24 Mk I.

When I need a wider lens than the Canon (quite often when photographing covered bridges) I use the Sigma.

Does this mean that you prefer Canon at 17mm and over?

Nor really.  For IQ I do not prefer one over the other.  At f/13-16 I do not see a big difference (I am not a pixel peeper but have sold prints up to 24" X 36" in size).  For me photographing covered bridges the 17-40 covers the range I need 90% of the time.  I very seldon have to change lenses.  If I used the 12-24 I would change lenses to my 24-105 maybe about 40% of the time.  So, it is for convience that I like the 17-40 for covered bridges.  When I go on long hikes and want to minimize weight I take the 12-24.

Now, perspective distortion is an other story on loss of image space but that is what you have to work with all UWA lenses, including primes.

Can you roughly quantify the loss on image space in any way or is it more like a "case by case" scenario (i.e. shoot at 12mm and after distortion correction looks like it was shoot 14mm)?

No, for the sigma 12-24 shooting at 12 mm you loose practically nothing due to optical distortion correction.

You loose image space depending on how far from horizontal you are shooting due to perspective distortion.  Point any 12 mm lens (prime, zoom, any manufacturer) at 10 degrees above horizontal and you will get the same amount of loss due to perspective correction.  This is a matter of physics, not lens quality.  The only way you can get around this is with perspective control lenses which are very expensive.