Autofocus is silent and spot on; I don't use manual focus much, but it's intuitive and easy to use

If you are shooting a straight subject like a group of people in a line-up and want everybody to be in perfect focus you will have to use high f-stops or avoid the wide end of the focal range

I have tried two samples of this lens, and they both behave the same: severe back focus.

All of them are sharp, fast and accurate focus

When I first tried it out in a shop I was amazed at the fast focus and that was using a 30D

Really quiet AND fast focus; the autofocus is almost noiseless and it focuses VERY fast

Great all around lens, fast focusing, sharp as a tack, super clarity, I highly recommend this lens

Does need to be serviced at least once a year to keep focusing sharp.

The focus is fast and sharp on my Canon

Great all around lens, fast focusing, sharp as a tack, super clarity, I highly recommend this lens

only to find that only 3 were in sharp focus.

5 business days after I mailed the lens to Irvine, CA, I received the lens back with a loose focus ring and the accompanying letter said "Your product has been examined and it was found that the internal component was broken and therefore the image was blurred

Full time manual focus is available, which is nice to have5

Very fast focus, true colors, sharp and just plain excellent lens

Can't figure out why it's opposite.- the copy I got had a slightly loose focusing ring and i sent it back under warranty and it was fixed.

as someone who owns the incredible 50mm 1.4 lens, possibly one of the quickest, sharpest and greatest affordable prime lenses you can get for your canon, i cant help but compare all other lenses to this as a golden standard.the focusing compared to the 50mm 1.4 is incredible

It takes crisp, rich photos, has a large apperature that makes for impressive low-light photography, and includes USM technology for lightening-fast focusing.

I'm very satisfied with it!Sharp image and fast focus...

lens mounted without any problems to my canon 20d and has a great manual focus

I love:-Smooth zoom\focus rings

Focus is very accurate as far as I can tell so far.

Extremely fast and quiet focus that is spot on target.

I use back-button focusing and the focus is fast and on point

I achieve very good results with a Tamron with VC (Vibration Compensation), but that's on a crop sensor and also after I learned how to deal with the very much slower focusing of the Tamron

I have often put an extension ring in front of it and used it as a macro lens, where it takes incredible shots using manual focus

I have found, personally, that the auto focus is incredibly slow and often back focuses (focuses on the background and not the subject)

apparently they both use USM motors, but this lens is very quiet and fast when focusing

Poor focus after 15', Images never sharp under any condition

The focus with my 1D is fast and accurate, its aperture is wide enough to shoot in available light, and the images are tack sharp and vivid

In the higher end Canon cameras the lens's maximum aperture enables additional focus sensors which enhance the accuracy of the focus further

Image Sharpness: When focusing manually, looks absolutely STUNNING.... if you get it right

but I was amazed at the lens fast focusing indoors in a low light setting and the ability to take photos in very low light

It is a fast-focusing lens.

I would say that this lens is very close to the new Canon 70-200mm II L Lens in terms of sharpness and fast focusing

Contrasty and colorful, no micro focus adjustments were needed

I have found, personally, that the auto focus is incredibly slow and often back focuses (focuses on the background and not the subject)

This lens is everything they talk about, it's fast focusing, nearly inaudible, sharp all the way to the edges on a 1.6x format camera.

Specifically, the focus works extremely fast and the images are sharp (which I could not say about the kit lens)

With the correct settings the lens is tack sharp, very fast focusing, provides great color saturation, etc

Focus is now consistent but the lack of sharpness is still disappointing.

The only issue I've had is the occasional back focus that tends to crop up most often when in 'one shot' mode (using my Canon 7D)

Not only does it extend down to 24mm, focus faster, control flare and ghosting much better, and implement manual-focus sensibly (including, like all ring-USM Canon lenses, the ability to adjust focus manually even in auto-focus mode), but it's much sharper

(There is quite a strong secondary market for used L-series lenses.)As for this particular lense: shot with it for the first time today and found the responsiveness, crisp focus and color saturation excellent in the digital domain

a shot comes up that I have to get, quickly (super fast focus, even in low light).

The build quality is top-notch - silky-smooth focus (USM + full-time manual focus)

It feels like several lens put into one and works like a dream; its focusing is fast and silent, its details sharp and stunning even at 3000+ pixels, and I could not be a happier girl with this lens in my hands.

The performance of this lens is great the focus is fast and accurate.

Manual focus also feels very nice on the touch/

Mechanics and Ease of Use: I love the larger focussing

Went to have it cleaned and was told screws were missing from the inside, the focus doesn't work and it looked like it had been taken apart

The images are sharp, the focusing is crisp and the ability to go to f/2.8 brings incredible options for low-light shooting

It's very sharp wide open, quick focus.

The images straight from the camera (40D and 30D Body) were super crisp, sharp focus (even at F2.8), and great saturated colors

Focus is extremely fast and accurate in combination of the 5D2 (normally ISO set at Auto)even in very low light indoor condition

The fixed the loose focusing ring and also stated that the "mechanical chassis was inoperable".

it can be more difficult to keep in sharp focus than most of my other lenses.

Even my friends, pro or amatuer, all say WOW! when they look through my camera for the first time with this lens on it!I love shooting with it wide open, while trusting the accurate auto-focus.

However, when it does acheive that perfect focus, the shot will rival the 135mm F/2 in terms of sharpness

When it misses absolute focus, you still get incredible pictures with no complaints

Great focusing, very sharp, great contrast and color

this is an amazing lens, and what 90% of my photos come fromI have the original and the II version of this, and besides being newer and the helpful focus-lock button, there isn't much difference between them - other than the bizarre $1000 price differencethe II version is slightly smaller, which is

I put it on my camera and drained the battery in a hour b/c i could not stop shooting random things around the house.

, I think the nod goes to the 24-70.Next, the extra reach (to 105mm on a full frame or 168mm equivalent on an APS-C like the 40D, 50D, Rebels).

L Lens looks like it ate my EF-S 17-85mm.

I like the versatility of my EF-S 17-85, but not happy with the ave colors or medium contrast or low end distortions