Sony SAL1650 focusing problem

Started Dec 14, 2011 | Discussions
razvu Forum Member • Posts: 71
Sony SAL1650 focusing problem

Hello all!
I purchased a SAL1650 that came in today.
My camera is a Sony A580. The lens is compatible with the camera.

After some testing I noticed some strange behavior: while in Focus check live, the focus motor goes back and forth and then in small steps until the object is in focus. This whole process takes 2-3 sec! If Focus live is off, focusing is almost instant.

My other Minolta lenses do not have this problem, focusing in live mode is fast, maybe a little slower than live view off, but definitely much faster than the Sony lens.

I will not talk about sharpness, yes it looked like really good picture quality, that's why I bought it, but this is totally unacceptable for a lens costing 700, especially when you read that the Sony live view focus is blazing fast!
It went back in the mail, for a replacement.

I also talked on the phone with Sony tech support and they did not have that lens in stock for testing, however they tested other two lenses and apparently they didn't have this problem.
If anybody else has the same lens and camera, can you please check this?

Steps to duplicate: camera in P (other modes were the same), press Focus check live view and try to focus on a few objects at different distances. Check if the focus motor goes back and forth (you will see the image getting blurred) and then you will hear it going in little steps until focus is achieved. This entire process takes 2-3 seconds. If you set Focus live view to off, focusing should be much, much faster, almost instant.

Sony suggested to replace the lens, this is what I am waiting for right now. They also asked me to let them know if this issue repeats, as there might be something they need to escalate to their engineers.
Thank you for looking into this!

 razvu's gear list:razvu's gear list
Sony Alpha DSLR-A580 Sony Alpha a99 Sony 24-70mm F2.8 ZA SSM Carl Zeiss Vario-Sonnar T* Sony 70-400mm F4-5.6 G SSM Sony 135mm F1.8 ZA Carl Zeiss Sonnar T* +5 more
Sony SLT-A58
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Solarcoaster Regular Member • Posts: 146
Re: Sony SAL1650 focusing problem

There is no problem with the lens or the camera.

The A580 is a unique camera in that it actually has two types of focusing in live view. If you press the Focus Check LV button, as you did, you get contrast detect autofocus (CDAF). This is the same type of autofocus that smaller point and shoot cameras have, and it is slow with any lens because the A580's sensor is large, and the sensor is doing the focusing. Other DSLRs have the same problem, technology will have to improve in order for this type of autofocus to get faster.

The second type is phase detect autofocus (PDAF), which is the same kind that you use through the viewfinder. It is very fast, although slightly less accurate, and it can track moving objects very well due to its speed, unlike CDAF. If you want to get PDAF in live view, don't press focus check live view, but instead move the switch to the left of that button from OVF to Live View.

By the way, this is the News Discussion forum. In the future, you will get better feedback by posting on the appropriate forum, such as Sony SLR talk or Beginner Questions.

Ralf B
Ralf B Veteran Member • Posts: 8,204
+ 1 on all what Solarcoaster posted

helpful, kind, spot on.
The forum to go to is
http://forums.dpreview.com/forums/forum.asp?forum=1037

even though it currently goes through rough times given the discussions and dogfights on the latest Sony offerings.
--
Ralf
http://RalfRalph.smugmug.com/

 Ralf B's gear list:Ralf B's gear list
Sony Alpha DSLR-A900 Sony Alpha DSLR-A700 Sony SLT-A55 Sony Alpha a99 Sony 16-35mm F2.8 ZA SSM Carl Zeiss Vario-Sonnar T* +14 more
OP razvu Forum Member • Posts: 71
Re: Sony SAL1650 focusing problem

Thank you, I think I posted it here by mistake...

 razvu's gear list:razvu's gear list
Sony Alpha DSLR-A580 Sony Alpha a99 Sony 24-70mm F2.8 ZA SSM Carl Zeiss Vario-Sonnar T* Sony 70-400mm F4-5.6 G SSM Sony 135mm F1.8 ZA Carl Zeiss Sonnar T* +5 more
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