Sigma 30mm f/1.4 EX DC HSM Autofocus Lens: Canon or Nikon $285, Sony or Sigma $289 + Free Shipping

Do we need to send body also. You can try sending just lens and tell them body name.

Yah. Focus ring is not smooth. It makes some sound during AF. Sound it makes during live view is a different story. Mine makes very loud sound with Live view focusing (Grinding sort of). I am going to check with Sigma and see if it is expected behavior.

According to Sigma's website, it defines HSM as "HYPER-SONIC MOTOR
This lens uses a motor driven by ultrasonic waves to provide a quiet, high-speed AF." Mine has the same sound intensity levels in both, on and of live views. I have seen here there are many who have the same problem like this. I wonder how Sigma would respond to the question on AF sound if everyone called to ask.

I just got my copy from B & H on Friday. I have just taken several shots with the lens, and the IQ is really good/sharp at f/1.4. It is lovely that I can take pics with high IQ at low light.

The problem I have with the lens is it doesn't sound smoothly when moving in AF mode. The lens is HSM, which is supposed to be quiet when focusing. I like the lens, but I am not sure about the little annoying click-click sound. Will it go away after a while? Or will it get worse later? Anyone has experienced the same, please command. Any feedbacks will be appreciated.

I have a Canon T2i. When I got this lens, I thought it was soft but I was wrong.

After reading this thread, I also performed some focus tests and noticed an obvious front focus issue. Initially I thought it was a lens problem (I almost returned it!), but then I repeated the test with my two other lenses (Tamron 18-250mm and Canon 1.8 50mm) and I got the same front focus result. After this point, I thought the T2i was the culprit, and I was right ...

The explanations on this link helped me a lot understanding the problem: http://www.photoforum.com/forum/p...-help.html.
Basically, the T2i has two alternative focus methods:
- Phase detection: this method is used when you take a picture looking through the visor (the reflex way). Focus is fast, but this method requires good calibration. Unfortunately, the only modern Canon model with focus micro-adjustment is the 7d (too expensive for a casual photographer like me)
- Contrast detection: this method is used when you take a picture looking through the LCD (T2i's "live view" mode), and it is the same method used by any point&shot camera. This method is very accurate, but slow.

I repeated the focus tests using "live view" mode and the front focus issue disappeared. I also took a few random shots in live view mode and they all were nice (not soft at all).
So, the problem is not my lens (at least my copy), the problem is that my camera's "phase detection" focus system is not properly calibrated.

After additional reading, this appears to be a very common issue with people buying a 1.4 lens: the depth of field is so small ("paper thin" as they say) that it will expose any camera focusing inaccuracy.
...

Looks like it is only live view specific issue. I did few more tests keeping eye on distance scale. Lens moves in small steps/increments in live view instead of one go focus movement. Each step produces this tuk noise. It also makes few more steps back and forth before the final focus confirmation. All this tuk tuk noise comes from this small step moves. Some times, this operation takes for few seconds and makes more tuk tuk noise. Probably, it moves in one go during phase AF instead of these steps

Other than this annoyance, live view with tilt screen looks like very useful feature for static subjects. We can focus any where on the screen instead of fixed 9 focus points with phase AF.

Thanks for this- it made a difference in my shots. I took all my shots my T2i, f 1.4, using a timer and tripod, and even so, over the twenty or so different shots there was a lot of variation in results. The truth, at least in my case, is that there's so much area for user error I wouldn't be able to judge how well the camera is doing. In any case I attached two shots with one using Live/LCD, the other the viewfinder and it does seem to be that the LiveLCD takes care of the front focus issue. The last one is just an example of a different a random different result using the view finder.

And use Live view also makes the motor clunk a little bit, it's louder.

Exactly! So what do we do now? Sending back to the vendor for return/exchange? Or sending the lens to Sigma to get it fixed?

So I just got my packages delivered from Beach Camera. It seems reasonably well focused to me, although I'm not expert. I've seen at least 2 different focusing test used in this thread, as well as miscellaneous shots of things around people's homes. Is there something a test that you'd like me to try?

Btw, the focus seems ok to me, although the sharpness seems better at 1.8 than it did at 1.4 but I just got it so I'm trying not to jump to conclusions

Edit: Ok so I tried taking some photos using the tripod from Beach Camera and I think that it's front focusing? This was shot at f/1.4 and ISO 100, center auto-focus point only, on a tripod with a 2 second delay. I approximated the 45 degree angle by making the height of the sensor the same distance away as the horizontal distance to the focus point (which was 40 inches in this case) I'm using a XS which is an older camera but i don't think should affect the focus. I like the specs on the lens for the price but it has to focus correctly, so I'm thinking of sending the lens with the body to Sigma.