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04-16-2011, 01:01 AM   #1
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cost for DA 16-50mm back focusing problems

I found out that I have a problem with notorious DA 16-50 focusing problems..

When my friend check the pictures taken by DA 16-50 1 year before,,,,
the pictures slightly indicate that the lens has a problem.

I bought it 2 years ago.... I have had a broken camera for a long time so I have not checked if is good or not.

I think I should send CRIS in Arizona to fix it.

Does anybody knows the cost to fix it?

thanks

04-16-2011, 08:43 AM   #2
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I'll be the first to admit that I don't understand the front/back focus problem at all. It just seems like it's something that shouldn't happen if tolerances are what they should be, unless we now have such high resolution cameras that mechanical manufacturing tolerances can't keep pace.

You don't say what camera you have but are you saying you can't fix this problem with lens-specific adjustments to your camera?

If the lens isn't under warranty, including the standard extended credit card warranty, I'd definitely sell the lens and move on. I wouldn't even think about trying to fix any performance-related issue with a lens if I'm going to be the one paying. Of course this assumes that there is actually a problem with the lens, and not the camera it's being used on.

It just seems like you have to check everything when you buy it, and that there is no good solution to problems after the fact.

Paul
04-16-2011, 09:06 AM   #3
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Paul is correct, it depends on what camera you use with the lens that you noticed the back/front focus issue. Did you do some simple test (such as using several AA batteries line up in different focal plane) to see if it is indeed the case? Did you tried the micro adjustment on the camera? If the problem is BF/FF with the lens, I think you will need to send in your camera as well, the problem could be fixed with adjustment on the camera in some cases.
04-16-2011, 11:33 AM   #4
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My older cameras don't have the presets for front/back focus. I do have focus issues, mainly with wide-angle settings on my zooms, but not true back/front focus issues, more like focus consistency issues. I can't manually focus those lenses precisely on my standard-screen pentamirror cameras, so I'm at the mercy of autofocus and it isn't always accurate. With important pictures I try to "bracket" focus, just by taking several pictures and re-locking focus (maybe on a slightly different object at the same distance) each time. With my 10mm, for distant objects I turn off autofocus and use the scale to focus. I've had two copies of that lens and although they autofocused differently, neither could focus consistently at the wide end.

So you really have to figure out the problem you have and if it's body-dependent.

When you buy a new lens it's a big advantage if you can test it on two bodies vs. one. If it works without tweaking on both bodies, definitely keep it!

Paul

04-16-2011, 04:31 PM   #5
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jajajab "I found out that I have a problem with notorious DA 16-50 focusing problems.."

tibbitts "I'll be the first to admit that I don't understand the front/back focus problem at all."
That makes two of us.
I am ignorant about optics so here is my question
How does a lens tell the body when it is, or assumes it is in focus?.
My understanding has always been that the camera focus system determines when the image is in focus.
Lens focus mechanism is just something that gets adjusted by the camera till it thinks things are focused.
In a case there is slop inside the lens, does the body just approximate and give up after x amount of attempts to focus
There must be an old post about this, just have not seen it.
The whole thing just does not sink into my technician head.
04-16-2011, 07:43 PM   #6
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Original Poster
Thanks for replies..
I bought the used 16-50 lens from B&H.
a week after I bought the lens, I broke my camera. K10d .
and 6 month after I was going to buy new cameras,, they were too expensive
so I had my camera fixed from CRIS. .
The picture I was talking about was taken after CRIS fixed my k10d.
some pictures from my 50-135 look very sharp when it focused on the center.
I remember that
I took pictures of lots of bottles as I focused the center, the picture did not focus in the middle of the center. it focused on somewhere behind the center. I thought it was nothing important.
and My k10d is broken again,,, the clip on my camera bag fell off,,, and I dropped it while I was just standing by the wall......
I guess I was unlucky.

English is my second language
I have tried to explain hard.
Thanks

Last edited by jajajab; 04-16-2011 at 08:07 PM.
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