I had read about this lens on how sharp images are even wide open, and how good the IS system works,So after doing same tests my self i can say this is one awesome lens,While shooting i went as low as shutter speed 1/13 at 200mm with the image stabilizer on, And it kept on taking sharp images ..

I mostly shoot landscape and nature and this is by far one of the best lenses I've owned. Even wide open it's amazingly sharp and focuses very fast. It will hunt a bit for focus in less than optimal light, but compared to the weight and cost of its 2.8 big brother this was by far the better option...

Fast / accurate auto-focus; Nice Bokeh; Rugged; Strong Construction

Heavy

Its compact size and Light weight can be deceiving when put next to its bigger brother, But at its f4 aperture the performance of this lens is truly amazing the IS system works well Testing it i went as low as 1/13 shutter speed at 200mm with IS on and it kept on taking usable images ..

Easy to use; Compact; Build quality

I need to purchase some additional lens filters and eventually I plan to upgrade to a full frame camera which is another reason in purchasing the "L" Series Lenses from Canon.

I am new to DSLR photography and about 1 year ago purchased the Canon T1i Kit; I then purchased the Canon EF-S 55-250mm f/4-5.6 IS Telephoto Zoom Lens for outdoor shots; The pictures were fine and blew away any of the point-and-shoot pictures I have taken over the past 15 years.

None so far; I do have to purchase another camera bag for all three lenses

I LOVE TAKING THIS LENS WITH ME ANYTIME IM OUTDOORS LENS HAS EXCELLENT SHARPNESS & UNBELIVEABLE LIGHTNESS AS WELL!!!

Consistent Output; Durable; Easily Interchangeable; Fast / accurate auto-focus; Lightweight; Magic Lens; Nice Bokeh; Rugged; Strong Construction

Ugh None Here

I bought this lens for a safari holiday based on these reviews. They are right - it is a fantastic lens. It is relatively light and well balanced on my 7D and I can walk around all day with the camera in my hand. It is tack sharp at all focal lengths, excellent contrast and colour.

Superbly sharp; relatively light; useful range; superb IS

None

This has been one of the best lenses I have ever had as a multifunction lens the best it the canon 50mm f-1.2 L series This lens is in addition to several other "L" series lenses that I own I shoot with a 5D Mark II, Canon 7D and the 450D (aks) the SXi.

I decided on the f/4. I was against the f/2.8 because it's twice the price, twice the weight and a fatter lens. (Then again, you need more glass for f/2.8...)I've been very impressed with the image quality. Every image I've taken has been razor sharp, with no noticeable CA.

Fast focusing; sharp; very lightweight; cheap alternative to the f/2.8 version if you can live with f/4

NONE

For years I have looked at the Canon 'white' lense and wanted one. Now, due to being able to upgrade to digital and Smifu's amazing prices, I actually own one. What a lense! Lighter than I expected and much clearer than the old Canon lenses (I got all my old gear out to compare).

A compact telephoto zoom lens from Canon's 'L' series.

Excellent optical quality; Superb build quality; Very effective image stabilisation; Fast to focus; Sealed against weather and dust; Light weight

Sometime miss-focuses near minimum focus distance