Hi, I'm Aaron Tubbs, and I like to shoot glass wide-open. It came to my realization that I now own three lenses with the same focal length, the three of which have different advantages in different situations. Here's Sigma's new 50/1.4 at 1.4, 1/50 at ISO 800 on a 40D; it's usable at 1.4 and provides dreamy bokeh; I like it:
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The Sigma is the only non-Canon lens I own. I like it because it doesn't change size when it focuses, it's fast, super-quiet, and it seems more usable wide open than the Canon 1.4. I hate it because it's large, has a shitty dusty-feeling finish despite the solid construction (I much prefer the exterior of my Canon 35/1.4L), doesn't seem to mate as firmly to the mount, and it is probably outdone by the comparable Canon when not shooting wide open (NB it only goes to f/16).
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The Canon 50/1.4 is the oldest piece of photographic equipment that I still own; I got it back in the nineties! It's noisy (for a USM), slow (because it's not "really" USM), almost useless wide open, and feels like a piece of junk. The comparably priced and performing 85/1.8 feels like a much more serious piece of kit.
If I want small aperture and big aperture performance, I sort of have to carry both with me, which is a bit of a bummer. If I had to pick one, I'd pick the Sigma, as I'd rather have the strong available light performance.
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My 50/1.8 II isn't something I'd compare favorably with either 1.4. It's noisy (not just comparably, as a non-USM lens, it's noisy), slow (not just slow like the 1.4, I mean real slow), frequently misses the focus, and it's a piece of plastic. Even Nikon puts a metal mount on their $120 50/1.8. On the upside, it costs less than $100, delivers decent performance, and doesn't look like anything. For EF-mount glass, it's the best value on the market; folks that buy a Rebel and use some nasty kit zoom should get one and give their zoom away. I keep it in a bag with a 28/2.8 and my 20D as my f/8 and there camera.
Anyhow, enough about my subjective thoughts. Below appears some very unscientific comparisons of the three lenses. I took only one photo in each scenario, so the results are guaranteed to be botched. In all cases I shot Av, AWB, ISO 100, on a tripod, with a 2-second timer. I think. You can check the EXIF and see if that's actually true, I may be lying. I warned you this was unscientific. All were processed the same way in DPP into jpegs. You can click for full-size jpegs as you wish.
Focus point is the word "VINOS" on the label of the wine bottle, give or take.
| Canon 50/1.4 @ 1.4 | Canon 50/1.8 @ N/A | Sigma 50/1.4 @ 1.4 |
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| Canon 50/1.4 @ 1.8 | Canon 50/1.8 @ 1.8 | Sigma 50/1.4 @ 1.8 |
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| Canon 50/1.4 @ 2.8 | Canon 50/2.8 @ 2.8 | Sigma 50/1.4 @ 2.8 |
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| Canon 50/1.4 @ 4.0 | Canon 50/4.0 @ 4.0 | Sigma 50/1.4 @ 4.0 |
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This part is almost completely useless. I didn't shoot 16 trials and take the best one. Each attempt got one chance, and one chance only. I didn't read the instructions; I have no idea how to actually test focus. As you can read from the photos, I printed a test chart from http://regex.info/blog/photo-tech/focus-chart/. Apologies to the author for not actually paying attention as to how to use the chart that was so painstakingly generated.
Measurement of the appropriate distance and angle was done via the "that looks about right, knowing nothing about this focus testing thing" method. None of them are representative of the lens capabilities, and I obviously completely missed the shot on the 50/1.8 at 1.8. As I say, don't use this for any serious comparison, but it at least gives a bit of a sense of ... well, just about nothing focus-related. To some degree it shows a bit of the resolution of the lens and how things aberrate, but even that's a bit of a stretch.
| Canon 50/1.4 @ 1.4 | Canon 50/1.8 @ N/A | Sigma 50/1.4 @ 1.4 |
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| Canon 50/1.4 @ 1.8 | Canon 50/1.8 @ 1.8 | Sigma 50/1.4 @ 1.8 |
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| Canon 50/1.4 @ 2.8 | Canon 50/2.8 @ 2.8 | Sigma 50/1.4 @ 2.8 |
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| Canon 50/1.4 @ 4.0 | Canon 50/4.0 @ 4.0 | Sigma 50/1.4 @ 4.0 |
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So, yeah, that's the stuff. If you have any further thoughts, you can probably figure out how to contact me here. Enjoy!