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10-26-2015, 12:54 PM   #1
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Sigma 150-500 focusing problem

Hi, i just got a brand new Sigma 150-500 for my K50 and as i found out it has problems focusing. So musch so, that when i tested it the other day i resorted to MF since AF was just hopeless. I mean i tried to follow flying birds like herons and it just wouldn't focus. It would hunt continously (and slowly) and it would even hunt on stationary objects. I tried all sorts of things but to no avail.

Now i wonder is it the lens, is it the camera, or is it me? Does anyone else have the same problem?

Should i return it and go for something else? I want a big telephoto and this was at a good price and admittedly i am very disappointed.

Is the Tamron 200-500 or the Sigma 50-200 any good? I might go for one of them as a replacement.

Your help will be very much appreciated.

Thanks in advance

Takis

10-26-2015, 01:18 PM   #2
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What focusing mode are you using? AF.C? Does the camera lock focus in AF.S? Have you tried focusing in Live View?

I don't have any experience with the K-50, but with the K-5 I never used AF.C. I almost always used AF.S with center point only. With the K-3 I use AF.C with Expanded Area AF. That is something not available with the K-50.
10-26-2015, 01:24 PM   #3
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QuoteOriginally posted by takis63 Quote
Now i wonder is it the lens, is it the camera, or is it me? Does anyone else have the same problem?
What's the light intensity like outside at the moment, where you are? It's a slow lens to begin with, and for continuous autofocus to work decently it requires quite a lot of light. FWIW, with the constant overcast weather and low autumn light intensity we've been having here in NL, I have not been able to use continuous AF with the DA 150-450, which is a bit of a faster lens than the Sigma to begin with; I have to use the more light-sensitive center AF point on my K-3 in most situations at present. However, during the summer months cAF worked like a charm, and on the occasional bright day it works fine even now.

For what it's worth, the modern Sigma AF motor seems to a bit slower than AF with other lenses, in my limited experience. The old 170-500, with screwdrive autofocus, was much faster on my K-5, but of course the optical quality of the newer models is much better, so that wouldn't be a viable solution.
10-26-2015, 01:33 PM   #4
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QuoteOriginally posted by boriscleto Quote
What focusing mode are you using? AF.C? Does the camera lock focus in AF.S? Have you tried focusing in Live View?

I don't have any experience with the K-50, but with the K-5 I never used AF.C. I almost always used AF.S with center point only. With the K-3 I use AF.C with Expanded Area AF. That is something not available with the K-50.
I tried to use AF.C but it was worthless. In AF.S and center point it would focus sometimes but sometimes it would hunt.

---------- Post added 10-26-15 at 10:37 PM ----------

QuoteOriginally posted by OJGoreng Quote
What's the light intensity like outside at the moment, where you are? It's a slow lens to begin with, and for continuous autofocus to work decently it requires quite a lot of light. FWIW, with the constant overcast weather and low autumn light intensity we've been having here in NL, I have not been able to use continuous AF with the DA 150-450, which is a bit of a faster lens than the Sigma to begin with; I have to use the more light-sensitive center AF point on my K-3 in most situations at present. However, during the summer months cAF worked like a charm, and on the occasional bright day it works fine even now.

For what it's worth, the modern Sigma AF motor seems to a bit slower than AF with other lenses, in my limited experience. The old 170-500, with screwdrive autofocus, was much faster on my K-5, but of course the optical quality of the newer models is much better, so that wouldn't be a viable solution.
The weather on Sunday when i tested it was very bright with lots of sunshine. I tried AF.S with center point focusing and this seemed to help but alot of times it would just hunt hopelessly. I tried it with OS on & off, camera SR on & off, only thing it seemed to help was AF.A in camera settings.

I have an old Tamron 70-300 from my film days and it works flawlessly. AF with it is fast and secure. If the Sigma was just as good i would be very happy.


Last edited by takis63; 10-26-2015 at 01:39 PM.
10-26-2015, 02:47 PM   #5
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A couple thoughts....I had problems when I wasn't shooting at fast enough speeds for the length of the lens (300mm shot at 1/25 isn't likely fast enough though it might be fine on more common focal lengths.).

Another thing to consider is the optical stabilization.....this lens has it (I think even two flavors), but your camera probably does too. Turn it off on one or the other and see if that might help.

Finally, though, I was still having challenges so I bit the bullet and sent mine into Sigma.....came back focusing very well, but it is a shame to spend that money on the lens and then spend more to get it working correctly.

Good luck.
10-26-2015, 03:00 PM   #6
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I have had problems with the auto focus from time to time on fast moving objects, but most of of the time my 150-500 works fine.

I just had to send my Sigma 10-20 in for warranty service and they did a great job, sent in on a Monday and returned to me on Thursday working great.
10-26-2015, 03:40 PM   #7
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QuoteOriginally posted by takis63 Quote
Hi, i just got a brand new Sigma 150-500 for my K50 and as i found out it has problems focusing. So musch so, that when i tested it the other day i resorted to MF since AF was just hopeless. I mean i tried to follow flying birds like herons and it just wouldn't focus. It would hunt continously (and slowly) and it would even hunt on stationary objects. I tried all sorts of things but to no avail.

Now i wonder is it the lens, is it the camera, or is it me? Does anyone else have the same problem?

Should i return it and go for something else? I want a big telephoto and this was at a good price and admittedly i am very disappointed.

Is the Tamron 200-500 or the Sigma 50-200 any good? I might go for one of them as a replacement.

Your help will be very much appreciated.

Thanks in advance

Takis
If you want to learn more about using the Sigma Super Telephotos this is a good place to go https://www.pentaxforums.com/forums/122-lens-clubs/279007-sigma-telephoto-zoom-club.html
10-27-2015, 02:59 PM   #8
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I contacted the store where i bought the lens today and they were surprised about this problem.

We are in contact with SIGMA Greece now to work out a solution.

Hopefully things will turn out OK

Thanks for all your help

10-27-2015, 07:01 PM   #9
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Not saying you may not be experiencing a problem, every super telephoto has a bit of a learning curve. If it was bright sunny and your subject isn't very close The lens will tend to hunt. When you are in that type of condition then I find it is best to set the lens starting at infinity and manual focus from there

Last edited by Oldbayrunner; 10-28-2015 at 07:31 AM.
10-27-2015, 10:52 PM   #10
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QuoteOriginally posted by Oldbayrunner Quote
Not saying you may not be experiencing a problem, every super telephoto has a bit of a learning curve. If it was bright sunny and your subject isn't very close Thelma will tend to hunt. When you are in that type of condition then I find it is best to set the lens starting at infinity and manual focus from there
I woke up early today to catch the full moon setting behind Mt.Taygetus and guess what, the lens seemed to be working much better than before. It would still hunt sometimes especially on grey coloured subjects, but it surprised me greatly. Much better performance!!! especially given the relatively low light conditions. The settings i used were : lens OS 1, camera SR off, AF.S, single focusing point.

I am confused for sure
10-28-2015, 07:38 AM - 1 Like   #11
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That's part of the learning curve. One can't pick up most super telephoto lenses and expect them to perform right away when using them. You need to take patience and learn how to get the best out of it for the situations you want to use it. That takes time.
10-28-2015, 09:07 AM   #12
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QuoteOriginally posted by Oldbayrunner Quote
That's part of the learning curve. One can't pick up most super telephoto lenses and expect them to perform right away when using them. You need to take patience and learn how to get the best out of it for the situations you want to use it. That takes time.
Maybe you're right. But the problem is i don't have enough time gor a learning curve. According to the store policy i have 14 days to return a faulty item. A friend of mine (a Canonian) bought a Tamron 150-600 and has had great success with it right away. No learning curve there, at least nothing serious like mine...

Today being a national holiday, i picked the camera at noon to test the lens once again and guess what, it didn't work...Again the same problems with hunting. I mean it wouldn't focus on a church tower 300m away!!!

The same settings that worked in the morning, now they don't. I remain greatly confused and i start to believe that the lens is faulty.

Will definitely ask for a replacement and see how it will turn out.
10-31-2015, 08:00 AM   #13
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So i sent the lens back to the store (under the warranty) and SIGMA Greece contacted me and said that the lens probably needs an upgrade to function properly with the K50.

Hopefully they will be able to complete this upgrade in house and send me back the lens within a few days. If they can't do it, the lens will have to go to SIGMA HQ in Germany and that will take some time, so i keep my fingers crossed...
11-08-2015, 07:28 AM   #14
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After being examined by the authorised SIGMA & PENTAX services, it was concluded that the lens was faulty. So now i am waiting for a replacement from SIGMA under the warranty.
11-29-2015, 08:06 AM   #15
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Good news. The new lens arrived yesterday from SIGMA and thankfully it works flawlessly.

I got a chance to test it today and i was thrilled. It is a great piece of kit.

I am very happy it all turned out OK

I have attached a picture of a falcon i shot today.
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