Sigma 17-50mm f/2.8 EX DC OS HSM FLD Large Aperture Standard Zoom Lens for Sigma Digital DSLR Camera

Absolutely my favorite lens of all. As a "semi-pro" and extreme hobbyist I must say that I like the quality of images from this lens on my Canon T3i even more than I like the quality of images from my Canon 5D Mark iii and the 24-70mm f2.8 L series lens; which would be the full frame equivalent to this lens on a APS-C sensor.Yes! I know that at this juncture some of you may be shaking your heads, but it is true. Granted, the 5D does have better image quality and more megapixels, but time and time again I get better images from this lens on my crop sensor cameras. Would you rather get almost the same image quality out of a lens that is 1/4 the expense? I sure as heck would.This lens paired with a T2i, T3i, T4i, or T5i will yield similar or better image quality in most situations than the 24-70mm f2.8 L series lens will on a full frame camera. Which if you are on a budget this is the lens for you!The images are so tack sharp and spot on. I read through many of the 1 star reviews and realized that the majority of the complaints come from Canon users that "got a bad copy" of the lens. As for me, I have a great copy. It is 3rd party glass but better than ANY canon glass I own (Once again some of you are shaking your heads). To me it's worth the gamble, and as long as you got it on Amazon and it doesn't work...send it back for a full refund!In addition to photography, the creamy bokeh that you get from this lens on video is astounding as well. The image stabilization, Optical Stabilization for Sigma (OS), is spot on. The only down side to the OS is that you can hear the gears working as you shift around hand-holding. Not so loud that it would be awkward while shooting an event.The focus ring has minimal resistance which I like; It allows you to get to rack focus faster. The auto focus is spot on and fast. The focus ring also stops at infinity focus as well at it's minimum distance. A feature I like because you know at what distance your subject is and you can switch subjects quickly. For manual focus you should be able to rack focus with a short minimal turn; unlike other lenses that require you to take your hand off the focus ring and do a second turn.Some would say that f2.8 isn't fast enough, but I find it to be plenty fast for most practical applications.You will not regret this purchase!

I was shooting for years with an 18-55 Nikon kit lens (on a D90); I chose to upgrade other parts of my lens family instead of the midrange zoom since it is a good quality lens for the price. But in a bad situation the camera made good friends with the pavement and the 18-55 caught the worst of it.What I was looking for that made me choose this lens:* a midrange zoom somewhere around 18-55 coverage, under $1k. I have a Nikon 55-200 and think you get better IQ by not combining the two ranges.* I've learned I prefer fast lenses since I frequently shoot in low light without a tripod and am a big fan of bokeh.* I often don't shoot in controlled environments so OS helps me get my shots. I've heard that the non-OS lenses are sharper, but I haven't noticed anything undesirable in the sharpness; and one shot you'd otherwise have missed to camera shake seems to make OS worth any loss in sharpness and increase in weight and cost.I'm extremely cautious about major purchases and spent months researching off and on. Nikon's options were more expensive, or were bringing me back to that 3.5-5.6 aperture which, frankly, is frustrating when you shoot manually 90% of the time and have to adapt quickly. Basically it was a battle between Tamron and Sigma offerings, and Sigma seems to frequently have the advantage in sharpness. Obviously both have their proponents but I have no personal experience with Tamron, so that combined with reviews led me here. This is my 2nd Sigma; I also have the 10-20 f/3.5 which is a stunning lens, and have shot with a Sigma zoom on a 35mm cam. While you will read a lot about quality control issues with third-party lenses, don't let it scare you off; just buy from a reputable seller and check the lens for any issues/decentering as soon as you get it. If you get a lens everyone else loves and you think is awful, swap it; it's QC.I'm still "learning" the lens since I've only had it about three weeks, but so far very impressed with it. The IQ is about the same as my 10-20, which under the right conditions will knock your socks off like a 2-3x pricier lens. Rich, realistic colors, sharp in the right places, and good contrast. Focus is fast and quiet (heard the Tammys sound like a dying robot). I'm obsessed with extreme close-ups of small things and like to get right in there with lenses, and have actually found you can get the lens to focus within its official max distance (managed about 8" from an object). You can get really stellar depth of field stuff with the 2.8 aperture, and it's smooth and even too. If you have a fondness for bokeh you're unlikely to go wrong. I'm a "serious hobbyist" I suppose, but this lens at this price would probably please a pro. I used credit card points to bring the price down which was a help, but I'd have paid full price for it.Pros:- overall image quality; good contrast, bright and rich colors comparable to a good Nikkor, good sharpness across lens- 2.8 constant aperture (once you've got constant aperture on a zoom you won't want to go back)- buttery smooth bokeh- optical stabilization- price to quality ratioCons:- relatively large and heavy- stiff zoom ring. VERY stiff. I hope it will loosen. (I have quite small hands so it may be less trouble if you don't.)- easy to snag rotating focus element on your fingers if you're not careful about your grip (not a big deal though)- large filter size (don't let this put you off; it's not a reason to pass on a lens)- very minor con: for some reason Sigma lens caps have a nasty habit of popping off without notice. Keep an eye on it.The pros definitely outweigh the cons though. This was my top choice after months trying to manage with only a Nikon 35mm 1.8 (wonderful lens, not ideal for everything though!). The combination of sharpness, color/contrast, bokeh, OS, and price make it an excellent choice the vast majority are unlikely to regret. I certainly prefer it to shooting product photos with a wide angle (fun times)!Quick note: Sigma lenses come with zippered cases, not pouches like Nikon; they have stellar padding but are bulky. If you ever transport your lens in an individual case while shooting, I recommend having a second case/pouch for it. I got a Domke lens wrap for putting this in my converted messenger bag.