Great lens for portraiture and very good for indoor activities and can be used for sports, but takes special care. What an incredible piece of equipment. I have been using the 135L, 70-200 IS and also the 85 1.8 for my portraiture work, which is the main crux of my business. I was previously pretty happy with the results of the 1.8, the flexibility of the 70-200 IS. I was and still impressed by the 135L, but found it a bit to long for 3/4 or waist up pose. I had been using the 70-200 IS and getting what I though were pretty good results. Then I got this lens. I now have 2. This is an absolutely amazing product. Yes, many have said that the 1.8 is close, which is true, but the difference in sharpness compared @ 1.8, 2.0 and 2.8 goes to the L. Also the BG blur attained by this lens is amazing. The 135L is also incredible, but in a different way. My portrait work has nit a new high, both because of the quality of this lens, and because I am inspired by the image quality to try new and different ideas, and I have a new excitement in my portraiture. this lens is so good, that I feel the need to back it up with another 85L. Yes it is expensive to do so, but I am a portrait photographer. Also great for any event work inside and can be used for indoor sports, but it does not focus very fast. You may get missed shots, or you could go to zone focusing, esp those of youu like me, who cut their teeth on an FM2, or similar MF camera. I am really nuts about this prime. For me it is a must have.
This is a very unusual lens, being so fast and expensive. You know that. You also know this lens is very big (about the size and diameter of a coffee mug) and heavy. What is less apparent is the bokeh on this lens. Others have addressed this, but I'd like to offer some further observations, even though I am a new comer to this lens. You can really get some strange effects with this lens that perhaps no other Canon lens at least can duplicate. The smoothness of the out of focus areas are amazing. I'll post some pics of this on this site. What you do have to deal with at f1.2 is a very shallow DOF. This creates the bokeh, but something in your frame has to be sharp. So this is an extremely demanding lens, not for the casual shooter. It's priced out of their reach anyway and Canon has done them a favor. You can get some serious purple fringing with this lens wide open, and even stopped down to f2. You'll see this in very high contrast areas, like a tree's limbs across a very bright sky. I'm using it to shoot some closeups where the contrast is not too high and I'm extremely pleased with the results so far. Nothing else compares to the smooth, almost luminous bokeh I see. I colors are extraordinarily blended into a very rich pallete, almost like a painter came along and filled in my photo with brush strokes.
Strengths:
Bokeh. Bokeh. Bokeh! No one will mistake you for an amateur with this lens. You'll know you have arrived as a photographer when you look down the maul of this beast. You are getting serious indeed! Light gathering capabilities: I shot regularly at 1/6000 of a second at ISO 160. Can handhold up to 1/100 of a second, so I've certainly got some wiggle room! Balance of the weight is good on my camera. I don't feel that the camera is going to fall over with this lens attached.
Weaknesses:
Cost. Cost. Cost! Demanding to use wide open. Easy to miss your focus and you'll just get a blur. Focus ring only operates when camera is on and metering is activated. Front element does extend over the very large focusing range this lens has. You have to focus to infinity to let the lens return to normal before you can store it, and you'll forget to do this before you turn the camera off.
Having previously owned a 85 f/1.8 Nikkor and a Zeiss 85 f/1.4, I can say that the EOS f/1.2 is the sturdiest and easiest to hold standard lens of the lot. I had an accident and dropped the 85 onto concrete from 3' and it is still working as adverstised. Build quality is excellent, and low light images are sharper than either of the other two lenses.
Strengths:
Build is great. Durability is tops. Wideopen sharpness is excellent. Internal focusing helps when skittish animals are watching you.
Weaknesses:
Auto focus is dead slow. Wide open focus suffers in the 10D viewfinder. Takes up plenty of camera bag space.
Let's face it. Every 85mm lens exelent. I believe 85~105mm are some sort of sweet spot designing finest 35mm SLR lens. sure 50mm sharp as hell but wide open performance never up to the 85mm quality. Another contender was medium range tele macro lens but these are totally different beast there is no way directly comparing these two group. For example 85mm/1.4 and 100/2.8 Macro lens, macro range to about 1 m(30cm~100cm) regardless any aperture setting macro lens is the best but ,at 1m~infinity, 85mm/1.4 Are superior even at same aperture setting. Eos 85/1.2 was typical fast moderate tele lens. I Concentrate on 7 finest 35mm lens comparing by excluding 100mm range macro lens. Luckly I own Five of them and two are rented. Here is the Magnificent 7.
Eos 85/1.2 USm(I own)
Eos 85/1.8 USM(rented)
Nikkor 85/1.4 AFD(I own)
Nikkor 85/1.8 AFD(Rented)
Maxxum 85/1.4 AFD(My wife's)
Pentax 85/1.4 A(Not FA Version)(I own)
Zeiss 85/1.4 MM(I own)
Conclusion
Zeiss 85/1.4MM--> Best portrait lens, best shadow detail, Compact size but substantial feel, High Built quality,best over all shapness at f/1.4. No AF, Even their AF Version and Contax AF system are pathetic.
Nikkor 85/1.4 all around portrait lens. Best AF 85/1.4 lens, Built quality,Second worst flare among 85/1.4 group,too contrasty, so so shadow detail.
Maxxum 85/1.4 real keeper Most cosistent optical performance interm of subject distance, aperture settings, best edge performace. Second best AF Performance My wife's favorate cute lens. at f/1.4 every other optical performance was exellent except for resolution. slightly soft wide often. But I suspect durabilty will be the last in 85/1.4 group even though sophiscatically manufactured.
Eos 85/1.2 slow AF due to the heavy focucing lens group. heavy, But exellent manual focucing feel. exellent wide aperture performance, Highest built quality(f/1.2,f/1.8f/2.0,f/1.4). Lowest contrast, flare prone lens, average edge performance, Average shadow detail. Overall exellent super fast 85mm lens.
Pentax 85/1.4 A compact,The best optical performance near 1M~3m. But the last optical performance at subject at infinity especialy resolution wise, The best flare resistance lens in the group. So so AF performance. But typical portrait range from 1.5m~5m At f/1.4. Simply You'll never see anything it before.
85/1.8 Eos and nikkor f/1.8 were neck and neck Built quality