http://www.photozone.de/canon_eos_ff/940-canon1124f4

The resolution characteristic varies substantially across the zoom range. Of course, the most difficult setting remains the 11mm setting. The center quality is absolutely stellar even at f/4. However, the borders/corners are soft here. Stopping down lifts the quality in the outer image region but not quite as much as you would have hoped. The best quality is reached at f/8 with good to very good borders and fair corners. At f/11 diffraction is already limiting the results. 
The situation changes completely at 14mm and 18mm. The center remains outstanding but the borders/corners are MUCHbetter. The borders are good to very good at f/4 whereas the corners are fair here. However, the corners are boosted to sharp quality at f/5.6 already. 
The performance goes a little downhill at 24mm again with softer results at f/4 and f/5.6 but f/8 is decent actually.

The centering quality of the tested sample was good but not perfect.

11mm에서는 주변부가 많이 아쉽네요.중간 줌 영역인 14mm와 18mm에선 주변부도 무난하고요.24mm에선 전반적으로 중간 줌 영역보다 조금 떨어집니다.

플레어는 새로 적용한 우수한 코팅 덕분에 상당히 잘 억제되었고요.물론 완벽하지는 않고요.

Verdict

Canon's latest additions to the ultra-wide arena have been impressive. The Canon TS-E 17mm f/4 L is awesome and the EF 16-35mm f/4 USM L IS is best in class. So is Canon's mojo sufficient to deliver greatness with the Canon EF 11-24mm f/4 USM L once more ... even on the EOS 5Ds R ? Well, they succeeded ... only partially. Now that's a bit of a harsh statement for a unique lens, of course. 
The center quality is nothing short of outstanding straight from f/4 and throughout the focal length range. However, the outer image region isn't all that hot at 11mm and especially at max. aperture and the high level of lateral CAs doesn't help either here. Moving on the 14mm and 18mm the results are much improved with good results even in the extreme corners. And let's be honest - most will use the middle range more often than the extremes on this specific lens. A decent scene composition is already very difficult at 14mm or 18mm and you will need to get used to having 11mm at hand as a new option really. The 24mm setting is a bit worse again but it remains quite good when stopped down a bit. 
The 11mm setting is also the (expected) weak spot in terms of high vignetting as well as heavy barrel distortion. These characteristics are much better again from 14mm onward. Activated auto-correction in your favorite RAW converter (or in the camera for JPEGs) will solve most of these issues anyway. 
Most ultra-wide angle lenses suffer from extreme flare in back-light conditions. Now the Canon EF 11-24mm f/4 USM L isn't perfect here - perfection simply doesn't exist here anyway - but it is a magnitude better than most other lenses that are at least capable of touching a similar focal length range. While we haven't tested the quality of the bokeh formally, we'd say that it is, again, better than most in this class (where most lenses perform dismal in this respect) although you will be able to see a bit of smearing and outlined highlights.

The build quality is exceptionally high and absolutely pro-grade. However, even though the lens body may be tough, the huge front element remains vulnerable. Due to its bulb-like shape protection filters are not possible. The new fluorine coatings will at least help to keep it reasonably clean most of the time. Remember that this is a massive lens both in size (well, diameter) and weight so it isn't exactly aligned to casual shooting really. Unsurprisingly the AF is very fast and near silent thanks to a ring-type USM drive.

That all being said ... what's the conclusion then? Honestly at this stage we'll not provide a further guidance because we just haven't tested a sufficient amount of lenses on the EOS 5Ds R yet. However, while many lenses can rule the common 20mp sensors, we can already say that Canon's new 50mp sensor is here to rule em all - less so in the image center but certainly so in the outer image region.

Optical Quality:	No rating at this stage
Mechanical Quality:
Price/Performance:

고화소 풀 프레임 바디에선 확실히 주변부가 문제가 됩니다.