Instruction: Answer the given question by extracting information from the supporting document.

Input:
Question: Will this lens work properly on a Canon Mark5 III?
Document: By the way, the weight of the lens by itself is quite heavy, but mounted on the Canon EOS 1D Mark III, it's well balanced in my hands. The auto focus was slower than all my other lenses, but not unbearable like some had noted. Fast enough for portraits, but maybe slow for sports photography. Looking past the sticker price, I'm thrilled to work with this lens and hoping to get eye-catching images.
In this case, where the autofocus on the Canon is so mediocre, the Zeiss is a strong competitor. The Canon lens has a slightly larger maximum aperture, of course.This is the second generation of Canon's 85mm L-lens; perhaps Canon will fix the autofocus problems in version III one of these years. If they also shave a few hundred dollars off this price, this will become a first-tier lens. Until then, I'm happier with the 135mm.
I shot this on three cameras while testing it: Canon EOS 1Dx, Canon EOS 5D Mark III, and a Canon EOS 60D. On all three I manually set the ISO range to 100-400, and used center spot focusing exclusively. I also shoot in full manual, continuous shooting. I did not miss a shot. I did not run into issues with clarity.
This is a Canon lens in the Class with the Legendary 200/1.8. It provides vivid color and contrast with a razor thin DOF. If you are serious about your photography and like to work in low light or do lovely detailed work this is must have. I don't know why I waited so long for mine.
I got this lens for portraits, weddings and for shooting flat art work. ~~ For now I'm favoring my Canon 55mm f/1.4, over the 85mm f/1.2L. for portraits and weddings. ~~ This may very well change when it comes to shooting more weddings inside under particularly dark conditions and evening receptions where lights are set way low and candles are lit for the ambiance.
Since all other reviews here and elsewhere have praised the optical and mechanical quality of this outstanding lens I don't want to write another lengthy review. It's one of my most beloved lenses, and I'd change to Canon's system only for this lens, if I hadn't it already.But there's still one question left worth being discussed: how does it perform with an EOS 5D Mark III in real life?
It is so tack sharp when shot correctly, it is almost unbelievable. The color is more correct than with most other lenses, and definitely deeper, with a higher amount of contrast. Using the high end 1Ds Mark III body accentuates this effect a bit more.With that said, I would suggest that equal consideration be given to the 50mm f/1.2L lens, as I consider this to be an equal companion (a sister) to this lens.
This particular focal length is the ideal length for portraits, and for my particular skills, it gives the same results in shooting full body shots, or portrait shots with 2 and 3 people, as well.Be forewarned, this requires a certain level of skill, and a certain knowledge of the camera itself. Furthermore, I am shooting a 1Ds Mk III.
This lens is an elegant choice for intimate photographic work. It's everything you'd expect and they DO MAKE YOU PAY $$$ FOR IT. Get over the cost and you'll LOVE this lens.
For a work I prefer 50mm but image quality is simple better from 85. It's awesome lens so if you have enough money - buy it.Note: Don't try compare 85/1.2 with 85/1.8 - those are completely different lenses
Answer: Yes, this lens is top of the line. Beautiful results. Keep in mind its 85mm its not a long lens but its not short, a 50mm is perfect indoors. I use my 85 for tight portraits. here's my image taken  with my 85mm 1.2  http://500px.com/photo/27766557.