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12-02-2010, 08:38 PM   #1
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DA* 55mm back focus...

So, I got my DA* 55mm... And what do you know? I love it! But there's a problem. It back focuses terribly. I dialed in a +10 adjustment on my K-7 and that pretty much fixes the problem at f/1.4 through f/2 but beginning at f/2.8 and on down the BF is so bad that even the +10 adjustment won't fix it enough.

What should I do? Send it back to asavings? They sold out of this lens so it would be a refund. Or could I send it in for warranty service? If I did do that, would it likely get fixed?

12-02-2010, 09:29 PM   #2
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You can send both the body and the lens to Pentax service centre which can match the calibration.
12-02-2010, 10:59 PM   #3
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Does not make sense at all. Focusing is always done wide open so aperture should not make a difference from that perspective.

Also, back and front focus should be less noticable at higher aperture numbers because deeper DOF will obscure it.

Exchanging the lens would be my first option.
12-03-2010, 06:15 AM   #4
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QuoteOriginally posted by sterretje Quote
Does not make sense at all.
It does make sense. Google "focus shift" for fast (faster than f2.0) lenses.

12-03-2010, 07:22 AM   #5
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Very interesting; learned something today.
12-03-2010, 09:42 AM   #6
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Am I out of luck then? Sending it in won't help will it? Is this is just a chronic problem?

See, I can't exchange it because asavings sold their inventory out.


12-03-2010, 09:49 AM   #7
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If it's just BF, the service centre will be able to program the body to compensate but they will need both the body & lens. It is different from MA or debug mode.
12-04-2010, 03:16 AM   #8
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QuoteOriginally posted by Ubuntu_user Quote
See, I can't exchange it because asavings sold their inventory out.
In that case I would just send the lens back and ask for refund. Then look for another copy either at other distributors / local shops or when asavings has it in stock again (just write down the serial number of this copy to be sure you won't buy and get the same lens next time).

12-05-2010, 01:28 PM   #9
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Yeah, ideally I'd like to just return it. But see, asavings doesn't give a refund on shipping either direction. Mhm, even though they sell something with "free shipping" when you return the item, they make you pay return shipping (okay, I can see that) but then they make you pay for the initial "free shipping," thus making it no longer "free." So, if I return this lens I'll loose a good $40, I'm guessing...

After this experience, I'm pretty much committed to buying from the "Big Two" (BH and Adorama). Asavings is just way too small of an operation to offer good CS.
12-06-2010, 09:37 AM   #10
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Ubuntu,

I sincerely wish the lens had worked to your expectations and I'm sorry that you're unhappy with our returns policy

The thought of defending it occurred to me, but I felt that would fall under the category of "blatant advertising" - and accordingly, some of the forum readers won't appreciate it.

I am thankful that you chose to buy from us, and of course, I hope you'll reconsider your commitment by evaluating the value of our offers, give our returns policy, in the future.

- Lior
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