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02-20-2011, 05:58 AM   #1
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Urgent opinion...is my 16-50 faulty?

Hi friends, i want a your opinion about my 16-50.
Observe this 2 images:

f5.6 40mm
http://img716.imageshack.us/img716/6406/49902333.jpg

http://img404.imageshack.us/img404/4563/91572681.jpg

Observes the right border: right border appears to me much more soft than left border.

Now i just read that a light asymmetry can be normal in a zoom...my question is: i must return it back or not?

02-20-2011, 06:17 AM   #2
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may be i'm not a pro at pixel peeping.. but i see fine... lol.. take some picture on something standard.. like a page of a book and it's much easier to compare
02-20-2011, 06:40 AM   #3
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I'm not an expert, but the image is not allright.
This could either be decentering or a problem with the body SR. Trythe same on tripod with SR off. If problem persists, the lens could be decentered.
02-20-2011, 06:47 AM   #4
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QuoteOriginally posted by elho_cid Quote
I'm not an expert, but the image is not allright.
This could either be decentering or a problem with the body SR. Trythe same on tripod with SR off. If problem persists, the lens could be decentered.
Thanks for the replies

The camera was on professional tripod and SR was OFF.

Another image:
http://img525.imageshack.us/img525/3810/76285112.jpg

02-20-2011, 06:49 AM   #5
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To begin with, several things. Your photos are over exposed. Everything in them is shot at an angle, nearly wide open, at a distance. Yes, in the second shot, the trees look softer on the right than those on the left. In the other photo, where the brick building is in the center, I'm not seeing any particular problem. In your third photo, I can see with the re-bar on the right that it is definitely softer than on the left.

Some of the original batch of 16-50 lenses were known to have decentering defects (3+ years ago). It was seen mostly however at 16mm f2.8. I hate to say this but if you want to test left to right sharpness, take a photo of a flat textured object equal distance from the left and right side of the lens. Also make sure you are focusing where you think you are. If you think you have a bad copy, return it for exchange or if possible, have it adjusted under warranty (probably the better option).

02-20-2011, 08:10 AM   #6
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The sudden drop in sharpness on the RHS is too obvious to argue. Return it w/o question, don't even try to have it repaired. Good luck.
02-20-2011, 08:46 AM   #7
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agree

QuoteOriginally posted by JeffJS Quote
To begin with, several things. Your photos are over exposed. Everything in them is shot at an angle, nearly wide open, at a distance. Yes, in the second shot, the trees look softer on the right than those on the left. In the other photo, where the brick building is in the center, I'm not seeing any particular problem. In your third photo, I can see with the re-bar on the right that it is definitely softer than on the left.

Some of the original batch of 16-50 lenses were known to have decentering defects (3+ years ago). It was seen mostly however at 16mm f2.8. I hate to say this but if you want to test left to right sharpness, take a photo of a flat textured object equal distance from the left and right side of the lens. Also make sure you are focusing where you think you are. If you think you have a bad copy, return it for exchange or if possible, have it adjusted under warranty (probably the better option).


I totally agree with JeffJS, test it in the right way and don't freak out, nothing is flawless.
02-21-2011, 10:12 PM   #8
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I agree with wlachan, there is a sudden and obvious drop in RHS sharpness clearly visible by looking at the window sills on the right in the second photo.

Best to do some brick wall or newspaper shots to cut out any variables that may be causing it.

BTW, is the location in India?

02-22-2011, 02:27 PM   #9
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I'd also say this is an effect of decentering. Mine does this as well but not as bad as yours.
Since the soft part is always on the right, I'd rule user error out.
03-27-2011, 05:04 AM   #10
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so much for pentax fixing this problem
got first copy end of jan, and it was decentered, that one wasn't too shocking but it also had some mark on front element on the inside so i sent it back, 2nd copy came in (higher serial number) and worked great but it was so badly decentered at long end it was going all blurry almost right from the centre.
03-27-2011, 10:01 AM   #11
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IMO that lens is clearly decentered. No doubt about it. Notice the RHS is not "soft," but clearly out of focus. I have seen this problem many times with the 16-50, and yours is consistent with those. Return it. Dont waste your time with taking any other pictures to test it. It is clearly out of focus on the RHS even though the items are in the hyperfocal distance range.

Also, decentering is not normal nor acceptable in a zoom. I have never heard that before except from people trying to justify a flaw on an obviously flawed item. Send this lens back for a refund. You paid way to much for sub par performance.

Last edited by PentaxPoke; 03-27-2011 at 10:06 AM.
06-01-2011, 03:00 PM   #12
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Ok, i solved, yesterday the 16-50 return from Pentax and now it's perfect, thanks to all for the support.

QuoteOriginally posted by selar Quote
I agree with wlachan, there is a sudden and obvious drop in RHS sharpness clearly visible by looking at the window sills on the right in the second photo.

Best to do some brick wall or newspaper shots to cut out any variables that may be causing it.

BTW, is the location in India?
selar, the location is south Italy.
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