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09-16-2012, 12:14 PM   #1
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Tamron 17-50 AF problem

My Tamron 17-50 is missing focus at 17mm. I'm using it on a K-5. AF is accurate at 50mm. Strange thing is, when I used it for a theater performance a couple of weeks ago, photos that I took at 17mm were in focus.

The problem occurs at both near and far distances. The examples below are near shots, but it is not focusing accurately at landscape distances either.

The first photo is the overall scene. The second is a 100% crop taken using phase detection AF, the third was taken using the LCD and contrast detection AF. IS was off, the camera was tripod mounted, I defocused between shots, and I used the 2 second timer. I took the same shot several times with similar results.

To me, this look like a problem that will require Tamron service. What do you think?

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09-16-2012, 12:31 PM   #2
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Tamron will just send it back saying that it is within normal Parameters.
Thats what they told me when I sent mine it for simular problems. Unless it's broke they will not fix it or adjust it.
09-16-2012, 01:20 PM   #3
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QuoteOriginally posted by Fl_Gulfer Quote
Tamron will just send it back saying that it is within normal Parameters.
Thats what they told me when I sent mine it for simular problems. Unless it's broke they will not fix it or adjust it.
I guess my only option is to send it to them and see what they do. The did fix a Nikon-mount 17-50 AF problem for me a few years ago.
09-16-2012, 08:27 PM   #4
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Tamron adjusted my 17-50mm F2.8 the other week, I had severe FF at all zoom levels wide open full adjustment within k-30 would still be 5cm in front of target. It's now in focus @ F2.8 but I cannot get equal front/rear bias at all zoom levels.

For example at 17mm F8 focal point is in focus, but also 3/4 in front and not 50-50 either side of the point yet at 35mm it will be perfect and 50mm different again. Such is the life with these lenses it seems /le sigh.

Still having it usable is great. Mine was given to the Tamron NZ distributor who couldn't fix and fwd'd it on to Tamron Japan (without my K-30 body). Cost me $115NZD or 95USD which was alright considering.

09-16-2012, 09:45 PM   #5
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QuoteOriginally posted by FruitLooPs Quote
Tamron adjusted my 17-50mm F2.8 the other week, I had severe FF at all zoom levels wide open full adjustment within k-30 would still be 5cm in front of target. It's now in focus @ F2.8 but I cannot get equal front/rear bias at all zoom levels.

For example at 17mm F8 focal point is in focus, but also 3/4 in front and not 50-50 either side of the point yet at 35mm it will be perfect and 50mm different again. Such is the life with these lenses it seems /le sigh.

Still having it usable is great. Mine was given to the Tamron NZ distributor who couldn't fix and fwd'd it on to Tamron Japan (without my K-30 body). Cost me $115NZD or 95USD which was alright considering.
If I understand correctly, your AF lens, mounted on an AF-capable camera, does not focus accurately, even after being serviced. How is that even remotely acceptable?
09-17-2012, 10:00 PM   #6
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Jeff, sadly this is a familiar problem with Tamron 17-50's. For years I've had to zoom in, lock focus and then zoom back to 17mm to get a crisp shot with mine. The dirty little secret is that some Tamrons just don't work all that well with the Pentax screw drive and can get worse over time. I finally sent mine back to Tamron for repair. When I got it back it worked better but was not flawless. I got a little more improvement when I upgraded to the K30d but it is still not 100% perfect. I've just learned to live with it. The lens is just too good to switch to something else. Zoom in all the way to 50mm to lock focus and then zoom back to shoot, if you can stand it.

Last edited by jeff knight; 09-17-2012 at 10:05 PM.
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