Sigma 70-300mm f/4-5.6 DG Macro Telephoto Zoom Lens for Pentax SLR Cameras

I have been using DSLR's for about 5 years. I started with the Canon t3i and when I wore it out I decided to move to Pentax with the K-5IIs. I chose this lens for it because it was both in my price range and had good reviews. That was the best choice I could have made! This is a top-notch lens, especially for the price. I had the long zoom kit lens for my Canon and it was loose and not near the build quality of this lens, nor was it as crystal clear. This lens allows the camera sensor to get the best information possible. I simply cannot say enough good things about it! The only annoyance, as others had noted, was that to zoom past 200mm you have to flip a switch, but its not the end of the world and you get used to it. I literally cried with joy at the images I could get with this. It is quick to focus, stays in the position I put it, is crystal clear, and oh the bokah! Depth of field is amazing, and I am convinced to get a shorter range Sigma for close-up work. You won't regret purchasing this lens. All the photos I am including were taken in low light on a cloudy day late in the afternoon or inside a building with no lights on. No flash was used, just the camera, lens and I.

Photography has been my hobby for 30+ years and I have a reasonable collection of lenses - Tamron 17-50 f/2.8, Pentax 50-135 f/2.8, Sigma 10-20, Sigma 100-300 f/4, SMC 50 f/1.7, SMC 28 f/2.8, SMC 135 f/3.5 and SMC 100 f/3.5 macro.While the Sigma 100-300 f/4 is great, it is heavy and not really travel friendly. I have been looking for a lighter tele zoom strictly for travel. I came across this Sigma but was not sure at first since I had an old Tamron 70-300 before. That Tamron was OK but no comparison to the Pentax 50-135 and Sigma 100-300. As a matter of fact, I wanted to return it before trying because I thought I ordered the APO version. On second thought, I gave it a try. But when I looked at the pictures from this Sigma, I was blown away by the quality. It is still no comparison to the Pentax and Sigma but much, much better than I expected. I did the comparison with the camera on tripod and mirror lock up and set ISO at 125.The main drawback is the relatively weak out-of-focus performance especially at the short end. Sharpness was very good for the entire range. Focus speed was quite acceptable on my K-x. At the same aperture and shutter speed, pictures tend to be about 1/3 stop darker than the Pentax 50-135. This seems to be the trend for Sigma since the other two Sigmas also show a similar behavior. But it is not a big issue. Construction is about expected for this price tag. The zoom ring is stiff between 200 and 300; better than too loose I suppose. It is too light for hand held at the long end; so it fits the travel requirement. I have not used it for macro yet.Overall, I am very pleased with this lens and it satisfies my needs quite well. Another reason for picking the Sigma over the similar price Tamron is because Photoshop CS5 has all of the lens correction information for the full line of Sigma lenses. I gave it 4 stars instead of 5 because of the construction.

I ordered this to go along with the Pentax K30 with 18-55 included lens. The 18-55 is weather sealed and takes a great regular shot but nothing compared to this self powered monster. We are newbies but when your photos come out looking like the magazine you know you have great technology in your hand.The lens has a motor which is important if your new because manual focus is a bit harder. I found it locks on easily enough and produces some of the best photos I have ever taken. As you lens shop you will be impressed at how decent the price is for what you are getting from this add-on.

Honestly, you get what you pay for. I'm not going to pretend this is the end-all of lenses or that it blew me out of the water. It's a very acceptable zoom lens for a very very decent price. I've been very impressed with the quality of Sigma's optics, and this is no exception. The lens is very clean, very crisp, and takes very nice photos. That said, the zoom is slow and noisy, and autofocus tends to just derp hardcore sometimes. When focusing on a very close or very far object, it will often zoom all the way in and out a few times attempting to focus on the object. These are all things I'm willing to accept for the price I paid. Pictures in the 80-150mm range come out very crisp and the lens is decently fast. 150-300mm definitely will require a tripod or other sturdy object unless it's very bright and you're shooting at 800-1600 ISO. It's good introductory lens and a great add-on to any Pentax K-5 K-7 or K-30 kit. All the negatives aside, I've taken some fantastic photos with this. It's done very well for daytime shoots of wildlife and I've gotten many "national geographic" type photos with it.The bottom line: If you wan't to be blown away with ultra-crisp photos at low ISO at 300mm, this lens is not for you. If you want a decent zoom lens that you will use with a tripod and mostly for daytime-use at a low low price, get this lens!

THis is a great lens but the auto focus only lasted a couple of years. I still have it but if I want to use it I need to use manual focus.