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Author Topic: White fringing on contrast edges Canon 24-105  (Read 1777 times)

David Sutton

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White fringing on contrast edges Canon 24-105
« on: October 20, 2011, 03:00:44 am »

Hi all. I recently upgraded from an Epson 3800 to a 24 printer and find to my horror that every tiny technical fault is now amplified for all to see. Working at 1:1 on screen is no longer enough and often it needs to be at 300% just to see what is going to be obvious in print.
In particular I am getting a white fringe on high contrast edges (image 1 below). Normally I would say that this is over-sharpening, except that:
1) is is only seen on files shot with my Canon 24-105 since I purchased it in 2007.
2) it is the same with all versions of Lightroom and all the cameras (350D, 40D and now 5D2)
3) I am fairly careful about sharpening in general and never sharpen edges
Out of curiosity I went back to the raw file and turned off Lens Corrections (image 2 below). Now that is interesting. I didn't know that the Lens Correction automatically dealt to chromatic aberration as well. Now I have a green line but still the white one as well. My capture sharpening is fairly modest, and third image below is with sharpening turned off. That has dealt to most but not all of it and I will still need to go over each file carefully and do some cloning on the edges. The posted files are at about 400%.
If I want to do capture sharpening with shots from this lens I can do two iterations of the raw conversion and blend them so there no capture sharpening on any edges, but I think I may be better off ditching the lens altogether.
I do mainly landscape and am covered on the 16 to 35mm and 70 to 200 ranges. The main contender then is the Canon 24-70 f2.8 USM L.
Thoughts and recommendations welcome.
Sorry for the long explanation.
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michaelnotar

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Re: White fringing on contrast edges Canon 24-105
« Reply #1 on: October 20, 2011, 03:28:34 am »

i read your post thoroughly, thats a sharpening issue only. a lens cant do that. i think your capture sharpening and printing sharping could be fine tuned. i did that between capture one and photoshop. i reduced the c1 pre-sharp, but for other reasons.  i think your radius is too high mainly. esp if you are going to up size the files then details will be magnified. so perhaps capture sharpening...?

re-reading your post again, while i have a keen eye for detail, i think that sharpening artifacts the white you mention is normal.
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David Sutton

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Re: White fringing on contrast edges Canon 24-105
« Reply #2 on: October 20, 2011, 05:41:55 am »

Hello Michael. Thank you for replying. A software solution would be easier than a new lens, so in Lightroom I tried lowering the Radius from .8 to .5, dropping the Detail to zero and the Amount to 19.  That will get the fringing to acceptable limits probably for 17 inch print, but no more. For a 24 inch print capture sharpening still needs to be off.
However, that may well be normal in larger prints and if that is the case I will stick with the lens.
FWIW, I tried DXO as well with similar results.
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Ronny Nilsen

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Re: White fringing on contrast edges Canon 24-105
« Reply #3 on: October 20, 2011, 06:29:42 am »

If you print out of LR, you might take a look at your output sharpening as well. That might well be the one step that introduce the problems in the print if it is to aggressive for the size/resolution.

Ronny
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Bart_van_der_Wolf

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Re: White fringing on contrast edges Canon 24-105
« Reply #4 on: October 20, 2011, 07:20:31 am »

Hello Michael. Thank you for replying. A software solution would be easier than a new lens, so in Lightroom I tried lowering the Radius from .8 to .5, dropping the Detail to zero and the Amount to 19.

Hi David,

The Detail slider gradually changes the type of sharpening from a USM type of sharpening at 0, to a Deconvolution type of sharpening at 100. USM produces halos, you can only reduce the radius and increase the amount to influence the result. Deconvolution sharpens detail without halos, but can also increase noise (use a mask to exclude smooth surfaces).

In Lightroom, the noise reduction settings play together with the sharpening settings, so changing one may require to change all. I tend to do no noise reduction if I can avoid it, and it may even not be as noticeable in print compared to display.[/quote]

Cheers,
Bart
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David Sutton

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Re: White fringing on contrast edges Canon 24-105
« Reply #5 on: October 20, 2011, 06:07:25 pm »

If you print out of LR, you might take a look at your output sharpening as well. That might well be the one step that introduce the problems in the print if it is to aggressive for the size/resolution.

Ronny
Hi Ronny. When I first noticed the fringing in print I went back to the image on screen at a higher zoom, and sure enough it was there. Just a matter of training my eyes to see it. I'm printing out of Qimage and getting a pretty good print to screen match now that I know what to look for.

In Lightroom, the noise reduction settings play together with the sharpening settings, so changing one may require to change all. I tend to do no noise reduction if I can avoid it, and it may even not be as noticeable in print compared to display.

Cheers,
Bart
Yes. For images with fog or large areas of sky I tend to turn the whole Detail panel off and look at the final result before doing any selective sharpening or noise reduction. The files from the 5d2 are remarkably good in this regard. In fact I have been adding a little noise to mask small imperfections.
I think I will leave Detail panel off now for any image I may want to print over 17 and do a single step sharpen in Photoshop where I can accurately control where the eye is led.
Cheers, David
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