[Edgar_in_Indy]

I just bought the Sigma 50-150mm f/2.8 lens a couple weeks ago, and it won't successfully autofocus in live view mode. It tries to focus, going in and out several times, but it either gives up, or it locks on but is very out of focus.

I can still return the lens, so I'm wanting to know whether I have a bad copy, or if this lens simply doesn't do well for contrast detection (live view) focusing. I'm using it on a Pentax K-x, and I haven't had any problem focusing in video mode with my Tamron 28-75mm or my Pentax 18-55mm.

Thanks!

[omega leader]

Does it focus with phase detection? I have it and it is my fastest and most accurate lens by far.

[Edgar_in_Indy]

Yes, it focuses just fine for standard shooting. (Although I think it has a tendency to front-focus when shooting closer than 15 feet, especially at longer focal lengths).

Have you tried auto-focusing yours in live view? If so, what happened?

[RBellavance]

See this recent discussion: https://www.pentaxforums.com/forums/pentax-k-5-forum/125732-sigma-50-150-hsm-...cus-lv-k5.html

Phase-detection AF does work in Live-view, but not contrast-detection. You will need to send your lens to Sigma to have its firmware upgraded.

Front-focus issues seem to be quite common with this lens. Mine is presently at Sigma Canada to correct a front-focus problem (not restricted to close focusing - see the thread linked above for all the details) and get its firmware upgraded.

Apart from the front-focusing problem, I have absolutely nothing negative to say about this lens. It focuses very quickly, it is very sharp right from f/2.8, and the build quality is great. At the price it is sold, and with the Sigma EX 10-year canadian warranty, it is almost a no-brainer to buy. Too bad it is now discontinued.

---

Last edited by RBellavance; 12-21-2010 at 11:49 AM.

[Edgar_in_Indy]

See this recent discussion: https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/126494-my-sigm...ml#post1310764

Hey, you just referenced THIS VERY THREAD! Are you trying to get me trapped in some kind of logic loop???

So how long has your lens been at Sigma? Do you know when it is expected back?

Too bad it is now discontinued.

As far as the lens being discontinued, I haven't been able to find any official announcement of it. I emailed them a few weeks ago, and a rep replied:

"We have not announced if it was being discontinued.

At this point it is just on back order with the corporate office so that is why it cannot be found in stores."

Kind of an ambiguous answer. For what it's worth, when I called customer support a few minutes ago they asked if it was the "OS" version. As far as I'm aware, there is no OS version yet, so maybe the current version is about to be replaced.

[RBellavance]

Hey, you just referenced THIS VERY THREAD! Are you trying to get me trapped in some kind of logic loop???

Oops ! I have now corrected the link: https://www.pentaxforums.com/forums/pentax-k-5-forum/125732-sigma-50-150-hsm-...cus-lv-k5.html

So how long has your lens been at Sigma? Do you know when it is expected back?

I dropped it off a week ago at the store where I bought it. No clear ETA, especially with the holiday period. I'm not expecting it back for at least 3 more weeks. I will definitely post a follow-up report when I get it back.

[Entropy]

I just got a K-5 Thursday - same issues with a Sigma 18-250 OS HSM.

I'm going to contact Sigma later this week.

[Edgar_in_Indy]

I contacted Sigma, and they confirmed that it should work in liveview. I've been asked to send the lens to them. They also requested that I send the body with it so the lens can be calibrated to the body. Kind of bad timing since I needed the camera over the holidays, but I'll probably send it in sometime over the next week or so.

[RBellavance]

I finally received my 50-150/2.8 HSM back today. I have not had time to test the AF accuracy, but I can confirm that it now focuses in Live View mode.

[Edgar_in_Indy]

So a little more than a month turn around time? Yikes! They asked me to send my camera in with the lens, but I don't know if I could go that long without my camera.

BTW, did they send you a CD with test pictures on it? I've heard that sometimes when you have a lens calibrated they often include something like that.

[RBellavance]

Well, I sent the lens just before the christmas/new year's holidays, so that meant an additional delay.

I did not get anything with the lens, and the service note they had at the store read something along the lines of "upgraded firmware and reprogrammed lens". I still have to properly test it, not sure when I'll have the time.

[Edgar_in_Indy]

Well, I sent the lens just before the christmas/new year's holidays, so that meant an additional delay.

I did not get anything with the lens, and the service note they had at the store read something along the lines of "upgraded firmware and reprogrammed lens". I still have to properly test it, not sure when I'll have the time.

So you didn't send your body in with the lens?

[RBellavance]

So you didn't send your body in with the lens?

No, I did not. I was not willing to spend the holiday period without a camera. Also, the fact that the lens required a different AF adjustment for each end of the zoom made me think that the problem was within the lens itself.

Still haven't had time to do proper testing. However, it seems just as sharp at 150mm as it was before... with the previous AF adjustment value. That had me slightly pessimistic.