Canon 24mm f/1.4 L USM II (vs Sigma 20 f/1.8)

 

Super bright wide angles are specialist lenses; they are great for night photos or low light reportage. In 2008, Canon announced the second version of the 24mm f/1.4: the new lens promise even better image quality. I have tested the 24mm f/1.4 II on my 1DsIII and I have compared it with the three-times cheaper Sigma 20mm f/1.8, the "night photos wide angle" that I currently use.  
 
Many thanks to my friend Sandro who loaned me this lens!  
 
As usual, I recommend to give a look to the page Testing and reviewing a lens: it will help you to understand better this review and my testing methodology!
 
 

Specifications (compared with similar lenses from Sigma and Nikon)

 
 

Built quality and autofocus

The built quality could not be better - it is practically perfect. Solid, professional, weather sealed: this is a first rate professional lens in every respect. The autofocus is performed by an ultrasonic motor; it is quite fast, very silent and it has full time manual focus.  
 
Its "poor man alternative", the Sigma 20mm f/1.8, has a reasonably good built quality, even though it is clearly not as good as the Canon 24mm. The autofocus, instead, is much slower and noisier; it lacks of full time manual focus. Both lenses lack of image stabilization...it would be nice to see a 24mm f/1.4 with IS, I think it would be an outstanding lens for handheld photography in very low light!  
 
I am very curios to test the new Nikkor 24mm f/1.4 to see how it compares with the Canon; in future, I'll try to get my hands on this lens and I'll publish the review and comparison on these pages :-)

 

 
 

Image quality (in comparison with Sigma 20mm f/1.8)

The Sigma 20mm f/1.8 is not a real competitor of the Canon 24 f/1.4, since there is an huge price difference, but it is the only Canon mount lens that has similar specification - super wide aperture and short focal length - so I decided to compare it with the Canon.  
 
I have tested the lenses on my Canon 1DsIII (21 megapixel, fullframe). The lenses were mounted on tripod; I have used mirror lock up and self timer. The following images are 100% crop from the unprocessed RAW file. The first series of crops is from the center, while the second and the third series are from the corners. The test subject was a big library (about 4.5x3 meters).

In the center, the Canon is a bit sharper, but there is not an huge difference. Both lenses show sharpness improvement by stopping down by few stops.  
 

 
 

In the corners, instead, there is a big difference: the Canon is way better than the Sigma at every aperture. The Canon is a lot sharper and it has less distortion; it is already fully usable even at f/1.4, while the Sigma is never really sharp even at f/5.6.
 
 

Samples and comments

These are some sample photos taken with the Canon 24mm f/1.4 L USM II on Canon 1DsIII. You can download either the untouched photo (JPEG converted from RAW without any additional post processing; minimum contrast and saturation, no sharpening, no AC, distortion or vignetting correction) or the post processed version. The untouched photo is a good way to see the real image quality of the lens, and the post processed versions allow to see the final quality you can get with good post processing techniques.

The 24 f/1.4 is a sharp lens even wide open; it shows little distortion and very moderate chromatic aberration. At f/5.6, the sharpness is impressive!
 
 

Conclusions

If you are looking for a bright wide angle and price is not a problem, the Canon 24mm f/1.4 is the best you can get for the Canon system; the built quality is superb and the image quality is great at every aperture. If you don't need the f/1.4 aperture or the very best image quality, instead, I'd recommend a 24-70mm f/2.8 zoom, that is cheaper and a lot more versatile (and it has good image quality, maybe not at good as the 24 1.4, but it comes close).  
 
The Sigma 20mm f/1.8 is a much cheaper alternative with similar brightness and an ever wider angle of view, but the image quality is much worse. I recommend it if you want a super bright wide angle at an affordable price, but you get what you pay for ;-) Of course, you can take good photos even with the Sigma, in spite of the poor image quality: many of my best night photos had been taken with this lens.