Sigma 18-125mm f/3.8-5.6 AF DC OS HSM ...- User Rating: 
Summary for Sigma 18-125mm f/3.8-5.6 AF DC OS HSM ...- A Good Walk-around Lens
Notes on Sigma 18-125mm f/3.8-5.6 AF DC OS HSM ...- This is a new lens from Sigma. I could not find any detailed reviews on the net before I bought it. It's a well built amateur lens with a nice focal length coverage that's not available from Canon. It's significantly heavier than Canon's 18-55mm plastic kit lens, likely due to more metal and glass used in construction. The focus is reasonably fast compared to Canon's kit lens and slightly quieter. For those who are familiar with Canon's ring type USM lenses, however, the this HSM lens is not a ring type HSM. This means it's not as quiet or as fast as the true ring-USM. And it does not allow "full-time manual focus". You have to turn AF switch off to manually focus the lens. This was a little disappointment for me for a lens at its price range. Sigma could have used a ring type HSM. Another thing I noticed is that while the OS (optical stabilizer) can be switched on or off, the OS gyroscope seems to be powered on even when the OS is off. You can hear the little noise from the piezoelectric gyro. My concern is that it can still drain battery power when OS is off. Optically, I am not in a position to say much because I have a 8MP camera. It's certainly adequate for me. Overall, I am happy with it and sold the kit lens that came with my camera.
Sigma 18-125mm f/3.8-5.6 AF DC OS HSM ...- User Rating: Summary for Sigma 18-125mm f/3.8-5.6 AF DC OS HSM ...- Just received this lens! First Impression.
Notes on Sigma 18-125mm f/3.8-5.6 AF DC OS HSM ...- Just received this lens. This is the first Sigma lens I got. Very good built quality. Hood is included and can be fitted front and back position. The construction is much solid compare to 18-55 kit lens. A bit better than the 28-135mm kit lens and size and weight about the same. I have not put on the lens on my 40D yet. I just like to share my first impression here. Also, the whole thing is made in Japan (including the cap). Don't know if that make any differences in your buying decision.
Update: I have been trying this lens for a while. It seems autofocus is not as accurate as my 18-55 IS kit lens. Sharpness with automatic shooting also not as sharp as 18-55mm. It also seems to produce a bit darker images compare to 18-55mm kit lens. My suggestion is, if you never need the 18-125mm zoom, go with 18-55mm IS kit lens and save money for lens such as 28-135 IS instead.
Update: I decide to give Sigma one more try, this time, the 18-200mm OS. After a week with 18-200mm OS, it's the best zoom lens I will keep. Sharp, fast focus, good color. Sharpenss is as good as 18-55mm, maybe even better. Sharpness throughout ALL zoom. I haven't find a soft spot yet. Skip 18-125mm, go with 18-200mm os instead.
Sigma 18-125mm f/3.8-5.6 AF DC OS HSM ...- User Rating: Summary for Sigma 18-125mm f/3.8-5.6 AF DC OS HSM ...- Versatile, good performing and affordable
Notes on Sigma 18-125mm f/3.8-5.6 AF DC OS HSM ...- After buying my Canon xSi I quickly concluded that I was not going to be satisfied unless I had a zoom of some kind to go with it. For a walk around lens, the modest 18-125mm range that this zoom offered, which is moderate wide angle to moderate telephoto, sounded very appealing. I am not all that keen on sports or wildlife photos, so I eschewed the available super zoom lenses, not just for cost but for weight, size, and image quality issues.
I've done pretty extensive tests on this lens, taking many tripod shots out my window in Chicago, trying different apertures and focal lengths, and comparing them to my two Canon lenses, and found it compared favorably. I found the Sigma's photos to be good looking and always in focus.
The OS works pretty well, and I was able to take two perfectly clear hand held shots at full 125 mm telephoto at only 1/15 of a second, though I had to use my best technique, as I suspect at full tele it's not hard to overwhelm the OS. Two more identical shots taken without OS were both blurry.
I've taken a few hundred shots with this lens so far and have no focus problems. Focus is fast and quiet. I took a number of shots of seagulls in flight at 125mm, a pretty challenging focus situation, and every one was in focus.
At 18mm this lens is a tiny bit less sharp than Canon's well-regarded 18-55mm IS kit lens that came with the camera, but as you zoom in the Sigma gets better, particularly at 50mm.
I will say that this lens is very sensitive to using just the right f-stop, while the Canon 18-55 IS is much more forgiving with shooting wide open. You MUST stop the Sigma down to somewhere in the range of f8 to f10 for best results at all focal lengths, and this makes the OS all the more necessary. I would not recommend using this lens wide open at any focal length. But once I knew what I was doing I took some very sharp shots indeed.
The telescoping part of the lens is very tightly constructed, with no looseness or feeling of imprecision at all, unlike the Canon kit lens. It has a zoom lock, but this doesn't seem to be necessary as there is no lens creep. I found this lens to be very well built and solid.
This is not a light lens. At about a pound it is twice as heavy as the Canon 18-55mm IS kit lens. Still, some of the superzoom digital lenses by Sigma and Tamron such as the 18-250mm weigh quite a bit more.
Overall I would say this is a very nice lens and I would buy it again. If you want the option to have one lens you can leave on the camera while traveling around, and if you're hooked on wide angle as I am, and if you also like telephoto but don't need a 200 or 250 mm superzoom and all the image quality compromises that can entail, this is the best and only choice for Canon APS-C digital cameras that I know of at this time, and I would recommend it.
