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03-10-2015, 10:59 AM   #16
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QuoteOriginally posted by photosbyspeed Quote
All this talk about science experiments and adding filters is pretty much a waste of time. Try focus peaking or zooming in on live view to get that sharp focus and minimize that fringing!
I think it's important that people don't think a UV filter will solve it, so I disagree with your 'waste of time' statement.

Also, nailing the focus won't resolve the situation either, it will just create sharper fringes. It is a characteristic of the lens, and stopping down - even as little as one stop - will likely help the most.

03-10-2015, 01:20 PM   #17
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QuoteOriginally posted by carpents Quote
It is a characteristic of the lens, and stopping down - even as little as one stop - will likely help the most.
Only if it is 'bokeh fringing' (LoCA), which is usually red/green, not blue/purple.
03-10-2015, 02:29 PM   #18
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QuoteOriginally posted by kh1234567890 Quote
Only if it is 'bokeh fringing' (LoCA), which is usually red/green, not blue/purple.
No, I'm talking about the purple fringing as seen in the OP. (Although you are correct about LoCA/axial color too.)
03-10-2015, 02:47 PM   #19
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Thanks Everyone!

Looks like good conversations between you all. I did shoot fairly close to the bike and they are crops of photos of the entire bike. True the second photo is a bit soft and I think the lens can do a bit better. I think the lens has SDM failure but I really didn't need the autofocus. One of these days I will send it in. It's a good universal lens for everyday shooting.

03-10-2015, 04:21 PM   #20
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QuoteOriginally posted by photosbyspeed Quote
All this talk about science experiments and adding filters is pretty much a waste of time.
I pretty much agree - learn your lesson and move on.

No more than 5 min in PS...

Last edited by wildman; 03-18-2015 at 08:19 PM.
03-10-2015, 10:03 PM   #21
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QuoteOriginally posted by kh1234567890 Quote
The K-5ii does not seem to have any great problem shooting a UV LED - I could probably get a better shot if I could be ars*d to set it up properly
Man, that is the worst purple fringing I have EVER seen


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03-10-2015, 11:30 PM   #22
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QuoteOriginally posted by kh1234567890 Quote
The K-5ii does not seem to have any great problem shooting a UV LED - I could probably get a better shot if I could be ars*d to set it up properly
You mean something like this? I will point out this needed a longer exposure than a visible light image would have needed. But then again the UV reactive ink wouldn't have been visible. I have been using this dye as an additive to improve the forgery resistance of my own fountain pen inks. You may be able to erase the visible colour dye but the UV marks will linger - even if you soak them in pure acetone.

Last edited by Digitalis; 03-29-2015 at 02:37 AM.
03-11-2015, 04:43 PM   #23
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QuoteOriginally posted by kh1234567890 Quote
Only if it is 'bokeh fringing' (LoCA), which is usually red/green, not blue/purple.
"Tamron's earlier Z-500 and CZ-500 models were unusual in that they were corrected for green and blue rather than red and yellow colors. This was preferable since most nature scenes predominately feature yellow and green colors, and since long distance telephoto photographs generally are affected by deep blue and UV haze. Nevertheless, the green-blue color correction in the earlier models resulted in significant amounts of red chromatic aberration and red lateral color. This significantly reduced the MTF for the earlier versions of this lens."

Tamron Adaptall-2 200-500mm F/6.9 Model 06A

I found this statement about '70's era (certainly pre-digital!) lenses to infer that color fringing could be at least party corrected and managed by optical design choices available at that time. New optical glass formulas and asymmetric lens surfaces surely add to the CA tool box today.

I've found that statement to be true regarding my own CZ500 compared to other Pentax and Tamron Adaptall SP tele lenses.

03-13-2015, 04:10 PM   #24
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QuoteOriginally posted by pacerr Quote
I found this statement about '70's era (certainly pre-digital!) lenses to infer that color fringing could be at least party corrected and managed by optical design choices available at that time. New optical glass formulas and asymmetric lens surfaces surely add to the CA tool box today
Before the use of super low dispersion glass, designers would have to correct 3(APO) or 4 colors (superachromatic) to prevent fringing. Now that these modern low dispersion glasses are common, the residual color can be greatly reduced without having to correct for 4 colors. Aspherical lens surfaces contribute to reduced distortion and reduced spherical aberration and do not affect color correction, at least not that I have heard.
03-13-2015, 07:47 PM   #25
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QuoteOriginally posted by desertscape Quote
. . . modern low dispersion glass . . . Aspherical lens surfaces contribute to reduced distortion and reduced spherical aberration and do not affect color correction,
low dispersion glass and Aspherical lens design have also allowed lenses to be much more 'compact'. Long barrels are no longer as necessary to minimize the bending of light rays to help control CA and fringing throughout the color spectrum.

A trade-off however is heaver lenses owing to the number of elements used to achieve corrections.
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