Purple fringe with Pentax DA 35mm f/2.4 AL Lens

Noggin · 10-18-2011, 01:32 AM

I just bought the Pentax DA 35mm f/2.4 AL Lens and was playing around with it at the weekend, I am seeing pretty bad fringing in high contrast images... is this a lens problem?

kanzlr · 10-18-2011, 03:15 AM

that's not bad fringing. look at what the Nikon 85/1.4 produces

Also, the part you are refering to is out of focus. out of focus means that the red, green and blue rays do not meet at the same point any more, thus aberrations like these are normal.
And every lens (or sensor) will exhibit this at hard black/white contrast lines.

aurele · 10-18-2011, 06:30 AM

show us the EXIF of the picture, but i bet you didn't stop it down enough.

JohnBee · 10-18-2011, 07:30 AM

I would say yes, to the optical question. However... I also think its worth mentioning that issues such as these are no longer issues given the tools that we have at our disposition today. And the first and formost method that I'd recommend for this is a very simple Photoshop maneuver that I like to call the gaussian army trick(because its very old). Which is nothing more than: duplicating the image layer, applying a gaussian blur and then assigning a color blend mode to it. And presto! you have a 5 second solution(3 if you're really quick on the draw

)

PS. in most cases, the issue can be addressed without further editing. But in some cases, it may be necessary to mask in the corrected areas so as to avoid color shifts or desaturation.

Having said that, the second and most profitable method of dealing with CA and OOF fringing is to shoot in RAW and use a developer like Raw Therapee. Which offers an elaborate set of CA a defringe correction tools.

Hope this helps.

**Just1MoreDave** · 10-18-2011, 08:44 PM

My FA 35mm f2, the starting point for the DA 35mm f2.4 design, can create some alarming fringing under certain conditions. I didn't notice it for the first year I owned it, then someone else took about 4 shots with it and had purple everywhere. Because the FA is already very fast, I almost always have the option of stopping down some when it does occur, which is still rare.

Noggin · 10-19-2011, 07:20 PM

Thanks for the replies, its an easy fix in PS I just wondered what caused it.

Laurentiu Cristofor · 10-19-2011, 09:24 PM

Originally posted by Noggin

I just bought the Pentax DA 35mm f/2.4 AL Lens and was playing around with it at the weekend, I am seeing pretty bad fringing in high contrast images... is this a lens problem?

Like kanzlr mentioned, this isn't so bad. Check my color fringing samples for worse examples. If this was shot wide open, I would say it's pretty impressive - what was the aperture?

Katsura · 10-19-2011, 09:46 PM

OP, you haven;t seen purple fringe until you have witnessed FA 77 Limited shooting into a bright background wide open

I had to rename some of my photos to Prince because of the purpleness.

10-18-2011, 01:32 AM	#1
Noggin New Member Join Date: Sep 2011 Posts: 21	Purple fringe with Pentax DA 35mm f/2.4 AL Lens I just bought the Pentax DA 35mm f/2.4 AL Lens and was playing around with it at the weekend, I am seeing pretty bad fringing in high contrast images... is this a lens problem?

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10-18-2011, 03:15 AM	#2
kanzlr Forum Member Join Date: Jul 2011 Location: Vienna Posts: 92	that's not bad fringing. look at what the Nikon 85/1.4 produces Also, the part you are refering to is out of focus. out of focus means that the red, green and blue rays do not meet at the same point any more, thus aberrations like these are normal. And every lens (or sensor) will exhibit this at hard black/white contrast lines.

10-18-2011, 06:30 AM	#3
aurele Veteran Member Join Date: Jan 2011 Location: Paris, France Photos: Albums Posts: 3,217	show us the EXIF of the picture, but i bet you didn't stop it down enough.

10-18-2011, 07:30 AM	#4
JohnBee Veteran Member Join Date: Sep 2008 Location: Newrfoundland Photos: Albums Posts: 4,667	I would say yes, to the optical question. However... I also think its worth mentioning that issues such as these are no longer issues given the tools that we have at our disposition today. And the first and formost method that I'd recommend for this is a very simple Photoshop maneuver that I like to call the gaussian army trick(because its very old). Which is nothing more than: duplicating the image layer, applying a gaussian blur and then assigning a color blend mode to it. And presto! you have a 5 second solution(3 if you're really quick on the draw ) PS. in most cases, the issue can be addressed without further editing. But in some cases, it may be necessary to mask in the corrected areas so as to avoid color shifts or desaturation. Having said that, the second and most profitable method of dealing with CA and OOF fringing is to shoot in RAW and use a developer like Raw Therapee. Which offers an elaborate set of CA a defringe correction tools. Hope this helps.

10-18-2011, 08:44 PM	#5
Just1MoreDave Site Supporter Join Date: Feb 2007 Location: Aurora, CO Photos: Gallery \| Albums Posts: 6,340	My FA 35mm f2, the starting point for the DA 35mm f2.4 design, can create some alarming fringing under certain conditions. I didn't notice it for the first year I owned it, then someone else took about 4 shots with it and had purple everywhere. Because the FA is already very fast, I almost always have the option of stopping down some when it does occur, which is still rare.

10-19-2011, 07:20 PM	#6
Noggin New Member Join Date: Sep 2011 Posts: 21 Original Poster	Thanks for the replies, its an easy fix in PS I just wondered what caused it.

10-19-2011, 09:24 PM	#7
Laurentiu Cristofor Banned Join Date: Nov 2009 Location: WA Photos: Albums Posts: 3,055	Originally posted by Noggin I just bought the Pentax DA 35mm f/2.4 AL Lens and was playing around with it at the weekend, I am seeing pretty bad fringing in high contrast images... is this a lens problem? Like kanzlr mentioned, this isn't so bad. Check my color fringing samples for worse examples. If this was shot wide open, I would say it's pretty impressive - what was the aperture?

10-19-2011, 09:46 PM	#8
Katsura Senior Member Join Date: Nov 2006 Location: Noosa, Queesnland Photos: Albums Posts: 199	OP, you haven;t seen purple fringe until you have witnessed FA 77 Limited shooting into a bright background wide open I had to rename some of my photos to Prince because of the purpleness.