Super wide on FF: Sigma 12-24mm at 12 or Canon 15mm plus defish

<p>The Sigma angle of view is 122 (diagonally) and the Canon before defish is 180 but I do not know what is the equivalent angle of the view of the 15mm after defishing.<br>

TIA</p>

<p> </p>

<p>That would depend on the amount of de-fishing one does. If I remember correctly (I calculated it once in terms of FOV) it was roughly the equivalent of a 16mm rectilinear...</p>

<p>Here's a pix taken with a 10D and the Canon 15mm Fisheye - and the de-fished version. This was done just to show you: note the black corners in the de-fishe version caused by the field shrinking as the pixels are stretched. This was done using the default setting in PT Lens, a PS plugin. You can do this in different ways of course, some of which will allow you more precise, manual control of the amount of de-fishing, etc... But, this will give you an idea because it's a straight up, default setting. Once you crop the picture to eliminate the black corner you end up with the final image, which is no. 3.</p><div></div>

<p>de-fished...un cropped...</p><div></div>

<p>and the final image cropping the dark corners out...</p><div></div>

<p>Since you are shooting FF you'll be wider than these shots which are cropped by the 1.6 sensor.</p>

<p>But, the question would be if you need a zoom or not. Also, I think the Canon is a MUCH better lens than the ultra-wide zoom you mentioned (if you can even use that on a FF Canon body).</p>

<p>Here's a pic taken with the Canon 15mm on a 5D - it's quite fun on a FF camera actually! I was able to include myself in the shot... ;p</p><div></div>

<p>Sigma 12-24 on a 5D, at 12mm. Awesome view.</p>

<p><img src="http://img.photobucket.com/albums/v490/alanpix/IMG_1526M2.jpg" alt="" /></p>

<p>No, it is not the sharpest lens. It's ok stopped down, it peaks around f/11 to f/16. I love it though, the wide view is quite amazing. How it compares to a defished fisheye in sharpness and/or width, I don't know.</p>

<p>Different lenses. Sigma dosn't have the funky look of fisheye - which is great for some purposes, but - optically it's very good. Extremely well controlled barrel distorsion, uniform sharpness (16-35L is better in the center). Very good resistance against flare when source in the frame. Stray light sources is a problem.</p>

<p>Built quality is - sorry to say (for Canon) - well ahead of Canon "L" series lenses. Silky smooth focus and zoom, it survived tip-over attached on 5D from ~120cm tripod on !concrete! with bent aluminium sun shade only. I have destroyed one 16-35 already and - it took not more than little bump to an edge by the lens when haging on my neck attached to the camera. The 16-35 lens mount is attached to the body of the lens by - plastic... Fragile one...</p><div></div>

<p>I'll second Peter's observations on the build quality (which is excellent) and low distortion (which is quite incredible for a zoom so wide).</p>

<p>However I have to say, I've found mine to be quite flare-prone for just about any bright light, in frame or out.</p>

<p>There are other quibbles, but ultimately if you want a full-frame zoom that spans this range, this is the best one because it is the only one.</p>

<p>Escalators at DFW.<br>

<img src="http://img.photobucket.com/albums/v490/alanpix/IMG_8014M.jpg" alt="" /></p>

<p>I am also yearning for the Sigma 12-24mm. The edge sharpness looks horrendous to me but you can't have everything on a zoom lens with such an insane focal length. I intend to use mine for candid street shots. People 2ft away won't have a clue they're being included in the frame.</p>

<p>Jorge,</p>

<p>Really does depend on the type of shooting.</p>

<p>With the Sigma, as noted above, it is flare prone and needs to be stopped down to be sharp. Remember to that trying to compose through an f5.6 lens is all but the brightest locales is not easy. Plus depending on the camera the AF may have a hard time and forget MF.</p>

<p>I sold my Sigma because of the above and replaced with a 16-35 MkI. While bright it was not the best performer - the Mk2 should be better.</p>

<p>But perhaps the Mk2 and/or the 14f2.8 are not in your budget? How about a 17mm Tokina or Tamron? Would be like the 15/defish angle of view and only $200/250.</p>

<p>About flare: I have found the Canon EF 15mm f/2.8 Fisheye to be quite resistant to flare, even shooting into the sun.</p>

<p>You can see several pictures I took with that lens <a href="http://sites.google.com/site/canoneosusers/canon-ef-15mm-f-28-fisheye">here</a> . No matter where the sun position was, there is zero flare, which I found surprising as I was expecting to see a reasonable amount of it.</p>

<p>Regarding the alleged poor corner sharpness of the Sigma 12-24mm:</p>

<p>I have found that after doing the autofocus thing you can tweak the corners by focusing manually with the focus ring. This is easy to do on the Sigma because you don't have to throw any switch from AF to MF to do it. As soon as the autofocus has locked on, merely give the corners a tweak. It seems to work, Someone explained the Sigma acted this way because it has such a curvature of field that you almost have to do this to bring the flat field into focus.</p>

 

<p>A couple 100% crops from the image above. This was shot on a 5D, 12mm, f/8, 1/10 second, hand held. There may be a little motion blur, but not much. First, the grass in the upper left corner,<br>

<img src="http://img.photobucket.com/albums/v490/alanpix/IMG_1526Edit2Crop1.jpg" alt="" /><br>

I would call that somewhat soft, though by no means unusable. F/11 or f/16 would be better.<br>

From nearer the center it's improved, though not spectacular.<br>

<img src="http://img.photobucket.com/albums/v490/alanpix/IMG_1526Edit2Crop2.jpg" alt="" /><br>

Not great, but definitely usable. I've printed 12mm shots up to 10x15 inches and they look fantastic right out to the corners. It's not as sharp as my 24-105/4, but I wouldn't expect it to be. Especially in the corners, it is better than my Tamron 17-35/2.8-4 at equivalent settings.</p>

<p>I would also add the vignetting is significant, especially wide open. Another reason to stop down. I haven't noticed much field curvature, but I haven't looked for it either. I generally shoot at smaller apertures with this lens, and the depth of field is very deep. I don't really have much problem with needing to use a lens like this stopped down. You're not shooting basketball with a 12mm. And it's quite easy to hand hold even at rather low speeds.</p>

<p>I intend to buy this lens soon. Just a quick question for those of you that have it... at 12mm if you set a small aperture of f11 or so, can't you just forget about autofocus altogether? With such a wide angle there will be huge depth of field to start with. On the street I could leave the AF off, set aperture to f8 or f11 and just keep shooting. Is this feasible?</p>

<p>Jamie, the answer of your question at dofmaster.com, for a FF, focusing at 1 meter, at 12mm F/8, the DOF is from 0.36m to infinite.</p>

<p>Excellent, thanks Jorge. So, at f8, there really is no need for AF at all. Makes for easy shooting.</p>