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08-02-2011, 03:19 PM   #1
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Lens defect?

Hi, I just purchased a Pentax zoom lens, and I'm getting very poor results. The photos are VERY soft and they have a strong halo to them. I checked the forum's reviews, and the lens generally received pretty decent reviews. No mention of softness and the strong halo effect. Does anyone know what might cause this softness/halo?

08-02-2011, 03:22 PM   #2
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Which zoom lens are we talking about in particular? Could you post sample shots by any chance?
08-02-2011, 03:29 PM   #3
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Is this a new or used lens? If used, there are almost infinite possibilities of what could be wrong, such as a film on interior elements, scratches on the surface, etc.

Paul
08-02-2011, 03:33 PM   #4
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QuoteOriginally posted by K57XR Quote
Which zoom lens are we talking about in particular? Could you post sample shots by any chance?
Hi, it's a used Pentax FA 28-105mm f3.2
Some sample shots here:

https://picasaweb.google.com/mika2k1/FA28105mmF32

.


Last edited by mika.; 08-02-2011 at 03:39 PM.
08-02-2011, 04:02 PM   #5
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QuoteOriginally posted by tibbitts Quote
Is this a new or used lens? If used, there are almost infinite possibilities of what could be wrong, such as a film on interior elements, scratches on the surface, etc.
Hi, Paul. I'm going to have a closer look at it tomorrow morning under some better light. Will report back then.
08-02-2011, 04:25 PM   #6
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The depth of field for f/4 at 43mm from 3 feet is 3 inches. Learn more about depth of field before complaining of soft focus. All of your photos were shot at f/4
08-02-2011, 04:29 PM   #7
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Forgot to include these links:
Depth of field - Wikipedia, the free encyclopedia
Depth of Field Table
08-02-2011, 04:32 PM   #8
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The first two at least do look rather like a soft-focus effect. Some outdoor shots in better light may improve results.

08-02-2011, 04:38 PM   #9
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QuoteOriginally posted by mdave13 Quote
The depth of field for f/4 at 43mm from 3 feet is 3 inches. Learn more about depth of field before complaining of soft focus. All of your photos were shot at f/4
I don't appreciate your tone of voice here. An aperture of f4 and 3 inches depth of field, should be more than enough to capture the objects in sharp focus. The photos are extremely soft and they have a very strong halo to them. Basically, garbage. I can show you comparable photos shot with other lenses, and the results are like night and day. Me learning more about depth of field is not the problem here.
08-02-2011, 04:40 PM   #10
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I own this lens, and it is certainly a bit soft - it's very much a portrait lens - the soft focus is a feature. If you stop it down 2/3 of a stop, it behaves very similarly to the other lenses at that focal length. Also, a hood helps.

Just started my Single in August with this lens, and it does well wide open.
08-02-2011, 04:45 PM   #11
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Still say the halos are caused by the razor thin depth of field. Take the same photos at f/8 and see if the halos disappear.
08-02-2011, 04:45 PM   #12
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QuoteOriginally posted by icywindow Quote
I own this lens, and it is certainly a bit soft - it's very much a portrait lens - the soft focus is a feature. If you stop it down 2/3 of a stop, it behaves very similarly to the other lenses at that focal length. Also, a hood helps.

Just started my Single in August with this lens, and it does well wide open.

I'll try that tomorrow. But it still doesn't explain the strong halo effect in the photos.
08-02-2011, 04:47 PM   #13
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QuoteOriginally posted by mdave13 Quote
Still say the halos are caused by the razor thin depth of field. Take the same photos at f/8 and see if the halos disappear.
I will. I'll post the results tomorrow.
08-02-2011, 04:49 PM   #14
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One other thing I noticed with my copy - it's supposed to have better flare resistance than previous models, but it scatters light kind of strangely. I get rainbow halos when I shoot the sun. I don't know if that has anything to do with the halos, but I throw it out there.
08-02-2011, 05:08 PM   #15
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Just a quick question

The effect your getting makes me think that you might have fogging on one of your surfaces, of either the lens or camera. I've had similar situation when the lens is taken from a cool location to warmer environment and it forms a thin layer of moisture. The look is great for portraits not so cool for everything else. But I'm not sure that's your situation, just a thought.
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