Canon 50mm f/1.2
By Jim Tanner

Center Sharpness
The usual DxO Blur Plots on the main site page for the Canon 50mm f/1.2L and Figure 1 below display considerable information about the Sharpness of the lens itself and, also, how it performs relative to the six lenses we included in this 50mm shootout. As you move the aperture slider in the Blur Index viewer from its lowest position (f/1.2) to its highest (f/16), you see that the Canon f/1.2L images start (f/1.2) reasonably sharp (less than 2 blur units) in the center, but with corners that are quite soft (4-5 blur units) and then steadily both flatten and get sharper until f/4, where the plot is very flat (no corner softness) and very sharp. This (flat, sharp) performance continues through f/11. Even though diffraction effects start to appear in the DxO results (but almost certainly not to the human eye) at f/8 and begin to degrade the image at f/16, the blur value of only 1.31 tells us that the sharpness is excellent, even at the minimum f/16 aperture. In other words, you get the best (overall sharpness) images in the range f/4-11, a reasonably wide "sweetness" range.

Figure 1. Center Sharpness: Canon 50mm f/1.2L versus the Group Average

Now, more about Figure 1 which depicts (in purple) the center-frame sharpness for the Canon f/1.2L over its full aperture range. The gap in the purple plot occurs because no data was taken at f/1.8 for the Canon 50mm f/1.2L lens. (There's no click-stop there, the f/1.8 data was only taken for lenses with an f/1.8 maximum aperture.) Also shown (in black) is a plot of the group average (of the six lenses employed in this comparison) blur value for the aperture range (f/1.2-f/45) spanned by the six lenses included in this shootout. The group average is shown at apertures where data is available from two or more lens (f1.4-/22). Generally, the Canon f/1.2L center sharpness performance is almost the same as that of the group; and real-life images by the Canon and "the six-lens composite" appeared (sharpness-wise) essentially identical. In fact, it's important to note that DxO asserts that blur differences of less than 1 blur unit are usually not discernible by the average observer. Over this aperture range the f/1.2L lens has an average blur factor of 1.11 blur units against a six-lens average of 1.14. The center sharpness of 1.80 blur units at f/1.2 is excellent for such a wide aperture.

Corner Sharpness
As we remarked earlier, interactive blur viewer shows moderate corner softness for f/1.2 and f/1.4.

Figure 2. Corner Sharpness: Canon 50mm f/1.2L versus the Group Average

This is verified in Figure 2, which plots curves of the Corner Sharpness measured for both the Canon 50mm f/1.2L lens and the group. This "moderate softness" is, in fact, better than the corner softness exhibited by the group average. From f/2.8 though f/16, the corner performances by the Canon and the "six-lens average" are essentially identical. At f/1.4, its sharpness is better than other lenses in the group, but not by much.

Chromatic Aberration
The DxO Chromatic Aberration plot on the main site page for the Canon 50mm f/1.2L shows the Maximum and (entire image) Average Chromatic Aberration for the lens over the full aperture range of the lens. While both the Maximum and Average CA are relatively constant over the full aperture range, both are very high relative to other lenses in the shootout.

Figure 3. Chromatic Aberration: Canon 50mm f/1.2L versus Group Average

The two purple curves of Figure 3 depict the same data shown in the DxO graph we just discussed, a graph that is included with each SLRgear lens review. The black curves of Figure 3 show the group maximum CA and average (over the entire frame) CA at each of the nine apertures in the f/1.2-f/16 range. Clearly, the Canon f/1.2L performs quite poorly relative to the composite group. Over this range the Canon f/1.2L average values of (max = 7.1, avg = 3.8) are well above the group values (max = 4.2, avg = 2.3). At the end of the day, the other five lenses in this shootout significantly outperformed the Canon 50mm f/1.2L in the Chromatic Aberration tests.

Shading (Vignetting)
The Shading (Light Falloff, Vignetting) DxO plot (the usual SLRgear presentation) indicates an initial (f/1.2) Shading of about 0.4 EV which falls rapidly through the lens aperture range (f/1.1.4-f/16) to a fairly constant value around 0.1 EV. There's little, if anything unusual here. (Note though, that we're only talking about performance on sub-frame cameras here: Check the Full-Frame Results tab on the main review page for this lens to see its performance on our EOS-5D test body.)

Figure 4. Shading: Canon 50mm f/1.2L versus the Group Average

Again, the purple curve of Figure 4 repeats the DxO graph discussed above and adds the group performance over the same aperture range. Over the f/1.4-16 range, the six-lens average is 0.16 EV while the Canon f/1.2L has an average value of 0.12 EV. Four of the other lenses have very similar Shading results with only the Nikon f/1.8 having a significantly higher average of 0.22 EV.

Distortion
DxO Analyzer performs two measurements for distortion by a lens, the Maximum Distortion and the Average Distortion over the entire frame. The Canon f/1.2L values (max = 0.22%, avg = 0.11%) are higher than the corresponding group values (max = 0.14%, avg = 0.06%). In fact, all five of the other lenses in this shootout have lower (better) Distortion values. (That said, the distortion levels of all these 50mm lenses are quite slight, to the point that you aren't likely to notice the barrel distortion unless you have some straight lines right along the edges of the frame.

AF Operation
Thanks to its USM motor, the canon 50mm f/1.2L focuses rapidly and very quietly. From infinity to closest focus (about 31 cm lens-to-target distance) the focusing time is well under a second even in relatively low light. At closest focus (on the 1.6x Canon 20D), the width covered is about 14 cm; about typical for a non-macro 50mm lens. Thanks to the USM motor design, manual focusing can be performed when in the AF mode; a nice benefit.

Build Quality and Handling
What more need we say? - It's an "L" lens and it is a tank! In hand, it feels solid as a rock. On the Canon 20D, the Canon 50mm f/1.2L begs for a larger body, say a 5D, or perhaps even one of the EOS-1 series bodies. It feels a bit out of balance (front heavy) on the 20D.

The Competition
The Table below summarizes the performance of the six lenses over the (f/2.8-f/16) aperture range, the largest range that is common to all six lenses in the shootout. In a later report, we will expand this table graphically by showing the full-aperture-range performance for each lens against each other lens for Center Sharpness, Corner Sharpness, Chromatic Aberration, and Shading. This will be a total of 60 graphs which reveal the dirty details of this intense competition.

Conclusion
Given its L-class designation and lofty(!) price, we found the 50mm f/1.2 to be a bit of a disappointment. While the center-sharpness and shading (vignetting) are excellent over the full aperture range, the wide-aperture corner sharpness, the chromatic aberration, and the distortion performances were all subpar. Could it be that our sample was not one of the better ones? We'll ask Canon for another one, and report here whether it tests better or not. If the results hold true though, it's hard to find a justification for spending $1,400 to $1,600 for a lens with this one's optical characteristics. (It's blur profile is somewhat better than that of t he Canon 50mm f/1.4 wide open, but $1500 or so strikes us as a lot to pay to get only reasonably good performance at 50mm and f/1.4)