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02-01-2009, 10:52 AM   #1
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Purple fringing on DA* 16-50

Hi all,
this my first real post
This weekend I buyed the DA* 16-50 and i tried to do some photos with my k20D.
Because I read many post about problems on this particular lens, and because I'm not an expert, I'd like to ask you if all is ok.
Below there is a photo with DA* 16-50.
The exposition:
21mm
F8
1/200
ISO 100
TAv



I see some purple fringing on the extreme left and right of the church.






In your opinion is the len ok?
Best regards
Marco


Last edited by spinmar; 02-01-2009 at 11:21 AM.
02-01-2009, 11:36 AM   #2
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Are we being a little too picky here? Who is going to notice that? I think most lenses will give you at least that much PF in such a high contrast area.
02-01-2009, 11:43 AM   #3
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Spinmar,

I'll give you a $100 for that piece of crap. It looks pretty good to me.

Tom G
02-01-2009, 11:57 AM   #4
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CA and PF are common issues that most Pentax lenses suffer from.
Luckily CA can be corrected in programs like Photoshop, and may improve the PF a little, but it won't go away totally.

People might be surprised to find out that our dear trilogy of FA limited lenses suffer from a lot of CA and PF in high contrast areas - that doesn't stop them from producing great images and being works of art themselves...

02-01-2009, 11:59 AM   #5
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Thanks very much for your replies.
So I suppose that my len is ok.
For an unexpert photographer it's no easy to understand if the len is ok or not.
Because there are a lot of posts which report problems with da* 16-50, I wanted to know if my len was defective or not.
So can I insert my serial number as ok?
02-01-2009, 12:18 PM   #6
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You should test it at 16, 24 and 50mm each at f/2.8 and f/4 on a background like a brick wall or garage door to look at sharpness throughout the image. No doubt, you'll find vignetting and barrel distortion at 16mm especially wide open, but sharpness should be quite reasonable at 100% throughout.
02-01-2009, 01:53 PM   #7
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When you stop down aperture to f4.5 and above, the PF problem is really minor.

If that really bothers you, use replace colour in photo editing programme with either blue or white colour.
02-01-2009, 03:14 PM   #8
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check this

I'm in the process of testing out my new 16-50 too. Check this, if you stop the lense down and look through it, is the aperture symmetrical? I feel like i'm getting a lot of CA, and I wonder if this is why. I need to do some sharpness testing still, but i'm just taking pictures to get a feel for it now. Anyone else have a lot of trouble with ghosting in dirrect light with this lense? I know dirrect light is though, but I'm talking about incandescent lights.

02-01-2009, 04:32 PM   #9
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QuoteOriginally posted by Ash Quote
You should test it at 16, 24 and 50mm each at f/2.8 and f/4 on a background like a brick wall or garage door to look at sharpness throughout the image..
I disagree. The OP should take photos and be happy.

We only have so many hours in the day. Does one want to spend it capturing moments and making art or doing test after test with the requisite pixel peeping? Although I suppose if that's what you're really into then it is fine...
02-03-2009, 02:05 AM   #10
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I'm a quite confused
Should I do some tests or not?
What do you advice me?
Best regards
02-03-2009, 06:32 AM   #11
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you can test all you want, but I think that people are reading too much and not shooting enough.

the issue with purple fringing is that it is simply a form of chromeric aboration, CA, where the colors when not in focus, do not all focus at the same point. It is a very difficult thing to control in any lens design, but the purple fringe is the easiest to see so people start talking about it.

in your last pboto, in the top left along the line of the eaves, you can also see green CA. no one picked up on that, only the dreaded PF.


to me your lens looks fine, and ifd you test, it should not be to post in some forum, but for you to understand the absloute limits of your equipment, and that is all,
02-03-2009, 06:44 AM   #12
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QuoteOriginally posted by spinmar Quote
I'm a quite confused
Should I do some tests or not?
What do you advice me?
Best regards
Do some tests, but remember that if you test to destruction, you end up with exactly that. The reason why so many people are unhappy with their cameras is simply because everyone now has the ability to do destructive testing without realizing the consequences.
Be aware that in some situations your equipment is going to fall down a bit. Test, if you feel the need, to find what those situations are, so that you can avoid them.

Let me give you an example of how I work. I don't "test" equipment in any formal way. I have some 50 lenses at my disposal, and to test every one of them every time I buy a new camera isn't going to happen.
I like to think I have a life.
I take pictures, and if I notice a problem during post processing, I determine what caused it and go from there.
I find that generally, problems that I can bring up on the screen are not problems when I make prints. A little CA isn't anything to get worked up over, it's something to deal with during raw conversion.
02-03-2009, 06:44 AM   #13
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Generally speaking, PF and CA all together is minimal to non-existant on the DA*16-50mm... well at least for me. But I am not much of a pixel peeper either.

02-03-2009, 06:55 AM   #14
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QuoteOriginally posted by Lowell Goudge Quote
you can test all you want, but I think that people are reading too much and not shooting enough.
.....
to me your lens looks fine, and ifd you test, it should not be to post in some forum, but for you to understand the absloute limits of your equipment, and that is all,
Thanks very much for your support.
Now I have only one thing to do: shoot, shoot, shoot
Best regards
02-03-2009, 07:03 AM   #15
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QuoteOriginally posted by Buddha Jones Quote
Generally speaking, PF and CA all together is minimal to non-existant on the DA*16-50mm... well at least for me. But I am not much of a pixel peeper either.

Ohh...
I hope that I 'll be able to do this kind of photo in the future....
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