This is my user review of the lens so I’d like to share some of the aspects not always covered in others. I know a few ocau members have this lens so any extra input is appreciated. After much research, I recently purchased the 135mm prime from canon. According to just about everyone else.. the image quality and sharpness were amongst the best and as I have found out myself.. I tend to agree with the excellent images obtained.. (not that I have tried every other lens out there). The range I find with this is great for wildlife photography, portraits.. especially head shots, low light photography, action photography, and pictures that you simply want some nice smooth bokeh. Those were the reasons why I decided to get one of these. Some of the other lens I was considering were the 200mm, 100mm and the popular 70-200.. however most of these only had an f stop of 2.8. I was looking for something a little quicker. When I first got the lens.. I found that it was a lot heavier than expected.. 750g according to the specs.. for its size but after comparing this to the 24-70, 950g, I suppose it wasn’t that bad.. its just that looks was a bit deceiving. Size wise.. it is shorter and not as thick compared to the 24-70 but certainly longer than the 17-40. I found the focus ring to be ideal for this size of lens. It has a nice thick band of rubber 30mm wide which is great when you adjust it with your left hand using thumb, second and middle finger. I believe this is the same as the 70-200 lens although I don’t have one to directly compare it with. The switches are the new version with a less obtrusive style that can’t be accidentally knocked which I like but from what I can gather most of the new lens or the ones which were manufactured say a year back all have these now. The lens I have was manufactured 4 months ago. I find there is no rubber seal around the edge of the back end of the lens compared to the 24-70 or 17-40. I suppose this is the water proofing of the lens when attached to the camera. This wasn’t such a big deal for me as I don’t intend to get any of my lens wet! But certainly it would have been a nice to have seeing how we all pay good dollars for our lens. The aperture opening of the lens is huge. From the front view you can see the difference this lens makes.! I was also surprised first of all by the amount of glass inside. I suppose this being my first under 2.8 lens. A good comparison with my other lens shows it quite clearly with all the caps taken off. The glass extends all the way to the edge of the barrel unlike the 24-70 where it falls short by about 10mm. It is very easy to see the blades work when you press the aperture preview button on your camera.. Click to view full-sized image! Hosted by UGBox Image Store Lens hood on this is big !!!! .. almost as big as the 24-70.. just 5mm shorter and about the same shortness in diameter. Kind of overkill in my opinion but I trust canon in its product. The 135 was manufactured with a slight tapering at the front end to fit a 72mm ring. I suppose the filter size could have been made to 77mm to match my others but you could also say the others could have been made to 72mm. I find that I shoot from f/2 – f/2.8 with this lens. Haven’t really tried any other.. Images are sharp even at f/2 when it is wide open. The depth of field is kind of tricky.. hard to get it right.. I tend to get it just in front or behind what I want in focus.. maybe it is just me with my clumsy fingers ! I find at f/2 the depth is very small.. e.g. one eye may be in focus but not the other or both eyes in focus but not the ears.. so be careful when choosing your aperture. The auto focus on this was very fast.. much faster than the 24-70. ! very good for low light shots as well.. I find the auto focus accurate as well.. occasionally I would use manual focus but not as often with this lens. It kind of has a slightly more noisy focus but not by much compared to the 24-70. It is a pity I can’t really comment on vignetting or corner sharpness or other distortions as I don’t have a full frame but with my 1.6 crop.. all is good .. nothing of the sort. ! To sum it up.. I find this my current favourite.! Nice telephoto range especially on a 1.6 crop. Pity there is no IS .. not that it needs it at f/2 but no doubt that would mean a hefty price and weight increase like just about every other lens with IS. Not much sharpening required in post processing if at all. Colours and contrast are good and balanced.. maybe a bit on the cold side but maybe it’s just me.. as I don’t calibrate my monitor. It’s a nice and fairly compact lens for its range.. so it is not so attention seeking. (until you attach the hood on !). as for zoom I have to use my feet and not my fingers do the walking. Also I can always get a converter to extend this to a 190 f/2.8 but the zebra look might be bit funny..! Would love to compare this with the 70-200 IS but time will tell.