12-05-2010, 01:51 PM
[quote name='Brightcolours' timestamp='1291553467' post='4768']
No, it does not. As I have said (and there is plenty to be found about it) the article is talking about loCA and showing loCA (green/magenta).
There is also something ELSE to be found, that is PF.
They are two separate things, and the article only touches on PF at the end to debunk "sensor blooming" and such as being a cause for PF. Of course, some "PF"-cases can actually be attributed to loCA, the magenta part. But that then is just a case for wrongly identified PF.
In short, the term purple fringing gets used for a number of different phenomena. It gets used for LaCA where magenta shows up as one of the offending colour edges. It gets used for magenta showing up with LoCA. And it gets used for purple/blue-ish or even red-ish occurrences that are neither LoCA or LaCA. And that, according to me, is PF.
What popo showed was clearly LoCA, with a green or purple edge ALL OVER the bokeh edge parts. That is very very inherent to loCA... it is coloured bokeh. And that is very different in character to the two cases of PF is showed, they are not related to bokeh but only to light intensity seeming to "radiate" into the dark surroudings, not even and not bokeh like as with LoCA.
[/quote]
Ok, let me quote that again:
"As the human eye and autofocus systems are particularly sensitive to green light, both manual focus and autofocus tend to bring the green image in sharp focus. The other colors of the spectrum are left defocused and add up to a magenta fringe. For this reason purple fringing is more common than green fringing."
To me it clearly says that PF is LoCA - just in this case you get purple fringing only, without its green counterpart.
No, it does not. As I have said (and there is plenty to be found about it) the article is talking about loCA and showing loCA (green/magenta).
There is also something ELSE to be found, that is PF.
They are two separate things, and the article only touches on PF at the end to debunk "sensor blooming" and such as being a cause for PF. Of course, some "PF"-cases can actually be attributed to loCA, the magenta part. But that then is just a case for wrongly identified PF.
In short, the term purple fringing gets used for a number of different phenomena. It gets used for LaCA where magenta shows up as one of the offending colour edges. It gets used for magenta showing up with LoCA. And it gets used for purple/blue-ish or even red-ish occurrences that are neither LoCA or LaCA. And that, according to me, is PF.
What popo showed was clearly LoCA, with a green or purple edge ALL OVER the bokeh edge parts. That is very very inherent to loCA... it is coloured bokeh. And that is very different in character to the two cases of PF is showed, they are not related to bokeh but only to light intensity seeming to "radiate" into the dark surroudings, not even and not bokeh like as with LoCA.
[/quote]
Ok, let me quote that again:
"As the human eye and autofocus systems are particularly sensitive to green light, both manual focus and autofocus tend to bring the green image in sharp focus. The other colors of the spectrum are left defocused and add up to a magenta fringe. For this reason purple fringing is more common than green fringing."
To me it clearly says that PF is LoCA - just in this case you get purple fringing only, without its green counterpart.