CZ1680 would not lock focus at infinity

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travelingman
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CZ1680 would not lock focus at infinity

Unread post by travelingman »

A few days ago while on a trip, I had a few moments to shoot a few snapshots from a scenic overlook with my CZ1680 and new a700. Everything was fine, but then I started having trouble getting focus to lock at the long end of the zoom and at long distances. There was enough contrast (bridges and buildings) that the autofocus sensor should have had no problems. Instead the lens hunted for a second or two, then stopped with the focus light flashing. I immediately tried a few things in desperation, power on/off, shift to aperture priority, shutter priority, focus method, but nothing helped. Unfortunately, I did not have another lens with me to to try. By then I had to be on my way and did not have time to investigate further.

Today, I finally had an opportunity to try to repeat this problem - I could not. Everything works as it is supposed to. I did change the battery this morning, but the one I pulled out was still showing about 75%, so it was not a case of low battery.

Anyone else ever have this problem? Anyone know what might have caused it? Should I be sending the lens/a700 body back to Sony for repairs - both are under warranty for many months to come. I hate sending something away for repairs when the problem is intermittent, or possible gone.
redsim74
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Re: CZ1680 would not lock focus at infinity

Unread post by redsim74 »

Are you sure you had the correct focus point selected? The one time I had a similar issue I'd knocked the focus selector from centre, to a point over flat sky.
Javelin
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Re: CZ1680 would not lock focus at infinity

Unread post by Javelin »

I've had this sort of thing twice. once on my A200 (kitlens I think) after a lot of hunting between very close AF points it stopped working and never locked focus. then a few weks ago on my A700 with my 70-300G the same thing happened. i'm pretty sure removing and reinstalling the lens with power on solved it both times and never happened a second time on either camera.. I think it was just a bad connection between the lens and camera
travelingman
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Joined: Sat Feb 28, 2009 10:03 pm

Re: CZ1680 would not lock focus at infinity

Unread post by travelingman »

redsim74 wrote:Are you sure you had the correct focus point selected? The one time I had a similar issue I'd knocked the focus selector from centre, to a point over flat sky.
That is certainly a possibility because this moring I noticed that somehow I did have the focus mode changed from spot to local. However, I dismissed that as the problem because my recolloection was I had move the camera around enough that anyone of the focus points would have had the contrast it needs to do its job. Of course, there is no way for me recall with certainty whether or not that was the case.

My targets were as least a mile or more in the distance, and there was water and sky in some parts of the photo, so I may indeed have just selected a focus point that was hitting that part of the photo, and of course that would not have enought contrast.

I think for the moment I am going to chalk this up to "user error" and hope that it never re-occurs. If it does, I will know to immediately look at this as a possible cause.

Thanks
travelingman
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Re: CZ1680 would not lock focus at infinity

Unread post by travelingman »

Javelin wrote:I've had this sort of thing twice. once on my A200 (kitlens I think) after a lot of hunting between very close AF points it stopped working and never locked focus. then a few weks ago on my A700 with my 70-300G the same thing happened. i'm pretty sure removing and reinstalling the lens with power on solved it both times and never happened a second time on either camera.. I think it was just a bad connection between the lens and camera
Well, as I mentioned, I did replace the batter this morning. That might somehow have had the same effect as changing the lens. I'll just have to wait and see now. redsim74 also provided another real possibility. So, I have two things to check or try if the problem does reoccur.

Thanks for your response.
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