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06-14-2012, 10:12 PM   #16
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QuoteOriginally posted by FrancisK7 Quote
You guys have any idea why the FA77 would do this?
Purple Fringing is not clearly understood or defined, but a PentaxForums user (sorry, don't remember who) has made a statement in the past that it is nothing but strong bokeh fringing (longitudinal chromatic aberrations - LoCA) behind the focal plane.

Take a look at the photozone review of the FA77. Note the example of purple fringing in the water and against the tree branches. And you thought yours was bad, eh? Now look at the LoCA sample below that - you can see that the fringing in front of the focal plane is of the same purple color. If you missed focus and focused behind the subject's head (it doesn't look to me like you focused on his face in the crop), then this could explain the purple fringe on the ear.

To verify this theory you should try to reproduce the effect in an area and then focus *in front of* that area - if you then get strong green fringing instead of purple, then this is it. Otherwise, the fringing is unrelated to LoCA and just an FA77 property.

Regardless of the source, such fringing is *not* something that you will find in all lenses. LoCA, however, seems to be a characteristic of all Pentax lenses since Takumars and up to FA series. The FA 31 behaves very well, but it uses an ED element. The DA line seems much less affected by it.

06-14-2012, 10:15 PM   #17
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Thanks for the explanation, very informative!
06-21-2012, 08:01 PM   #18
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Here is a good Purple Fringe Monster. I was experimenting with the aperture settings with my K5+DA 40 ltd. and this happened wide open at F2.8...This was just before sunset as it was setting to the left.

EDIT: I think PF knocks down the file size quite a bit. This was knocked down from 6.86MB to 322KB. On the larger file the PF is horrendous.
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Last edited by SuperK5; 06-21-2012 at 08:10 PM.
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