Sigma 14 mm EX f/2.8

Just picked up this lens, and I am in love with it. Took it out and did some tests with it today and I can not WAIT to try it out on some big ole supercell from 3 miles out.

This view shows the 90° angle of two city streets...

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While this one head on, shows almost no distortion of the straight curb. There is just a hint of slanting inwards in the pole on the left, and the brown house on the right.

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Bought it new from B&H for $850.

Doug Raflik
 
Although it's probably a very nice lens, there is quite a bit of barrel distortion except in the very center (where it's supposed to be non-distorted.

From everything that I can see, it all is "bent" to the middle. If your using a DSLR, and this is a "regular" 35mm lens, there shouldn't be that much distortion due to the 1.6 (or whatever it is for your DSLR) cropping factor.

If this is a regular 35mm film camera then it's probably about right for 14mm. As far as the clarity goes, it "looks" alright, just remember that with this kind of "bend" to the photos, you will also see that even more on storm structure shots as well as any panoramics you might do.

There are Photoshop (other photo editor?) plug-ins that will help reduce this effect, but they aren't perfect.

I guess it all depends on what you're trying to accomplish. Tight people shots in close in areas, you probably won't see the bend as much, Wide angle nature shots, it will give you a bowl effect that will be hard to compensate for.

John
 
Honestly it looked pretty good to me... PTLens does a nice job with correcting distorttion. I wonder how it compares to the 10-22 at 14mm?

Aaron
 
A 100% crop is where you take the full size *unedited, non-sharpened* image and then cut a small piece out of it at 100% resolution to see how crisp things are. Usually it's best to do this in the center and then also at the left or right edge. It also matters a lot what aperature you shot the photo at when checking quality -- try one at f2.8, then f4, then f8, to see how well it performs wide open and how far down you have to stop before it gets real crisp. Superwides by nature are pretty hard to get good edge reproduction on.

On paper, the Sigma looks pretty good, though not in the same league as the Canon L glass. Looking at the MTF for the Sigma 14 @ f8 & wide open:

SIAF1428EX.gif


It looks pretty good, though I would avoid f2.8 if possible.

Canon's old 14mm seems to wipe the floor with the Sigma, though, but the price is like $1,000 more:

ef_14_28mtf.gif


Given the on a 1.6x crop you won't see so much of the edges, and since the Sigma performs really well near the center, it's probably a great match to a digital Rebel or a 20D. I dunno if I'd want to use that on a 35 film based camera or one of the new full-frame digitals, though. (On the other hand, if you need 14 mm and shoot EOS, Sigma and Canon seem to be the only worthwhile choices. And for po' folk like me, Sigma would be the *only* choice!)

*edit*: How to read an MTF Note that with the Sigma, 10lp/mm, 20lp/mm, and 40lp/mm are shown, whereas with the Canon only 10lp/mm and 30lp/mm are shown. Basically, what this means is that only the 10lp/mm plots can be used for direct comparison between the two lenses. Which is probably the most important plot, anyway.
 
In your pictures, your targets are at or above roof level. To conceal the distortions, try aiming dead center at the horizon and see if those vertical lines on the sides start behaving a little better. You may lose some sky by shooting this way (and gain some boring foreground), but it might minimize the exaggeration of perspective you get from the extremely wide field of view. You can always crop out the junk on the bottom later if you don't like it.

This trick works great with my fisheye lens. In fact, it's the only way to get flat ground when shooting with it.
 
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