Doug
03-02-2010, 06:33 PM
Hi -- Looking for suggestions on how best to deal with CA's -Chromatic Aberrations- and Lateral Color and purple fringing. This seems to be a bigger issue with digital files than with scanned color negs.
Relatively new to digital, I hadn't really paid much attention to this matter until recently looking more closely at full-res processed TIFF files, and thinking of making prints. Specifically, looking at the same digital pics I've been uploading to the Gallery, all taken with the 24mm f/2 Pentax-FA lens. Looking at older film pics from this same lens, I see Lateral Color and purple fringing to a lesser degree.
Other lenses show less aberration, such as the 15mm f/4 DA and the Zeiss 28mm f/2 ZK. If/when I shop for a new lens, I'll now put more weight on the reviewer comments about CA's. Any experiences or opinions to share on avoiding the problem in the first place? Is this at all a function of the camera/sensor, or just the lens?
Then, maybe even more importantly, how can this effect be dealt with in post-processing? I have had Photoshop for years but never used it much. Pentax Photo Lab has sliders for Red and Blue CA correction. I've been experimenting and fine-tuning but it's difficult to get a handle on it... can't seem to get it all out. And it doesn't address purple fringing at all.
I have run some PEF raw files through CaptureOne, and my first impression is of less CA's in the output TIFF, even though there's no specific control to adjust for this. Maybe it does something about it automatically? I would think the pro users of C1 would certainly want to banish any CA's that might be in their files...
What are your thoughts?
Relatively new to digital, I hadn't really paid much attention to this matter until recently looking more closely at full-res processed TIFF files, and thinking of making prints. Specifically, looking at the same digital pics I've been uploading to the Gallery, all taken with the 24mm f/2 Pentax-FA lens. Looking at older film pics from this same lens, I see Lateral Color and purple fringing to a lesser degree.
Other lenses show less aberration, such as the 15mm f/4 DA and the Zeiss 28mm f/2 ZK. If/when I shop for a new lens, I'll now put more weight on the reviewer comments about CA's. Any experiences or opinions to share on avoiding the problem in the first place? Is this at all a function of the camera/sensor, or just the lens?
Then, maybe even more importantly, how can this effect be dealt with in post-processing? I have had Photoshop for years but never used it much. Pentax Photo Lab has sliders for Red and Blue CA correction. I've been experimenting and fine-tuning but it's difficult to get a handle on it... can't seem to get it all out. And it doesn't address purple fringing at all.
I have run some PEF raw files through CaptureOne, and my first impression is of less CA's in the output TIFF, even though there's no specific control to adjust for this. Maybe it does something about it automatically? I would think the pro users of C1 would certainly want to banish any CA's that might be in their files...
What are your thoughts?