stanley_rogouski Posted July 24, 2003 Share Posted July 24, 2003 <p>A particularly egregrious example of CA, courtesy of the Sony DSC- S85 (a pretty good little camera over all). <p/> <p><img src=http://rogouski.net/loose-photos/purple-fringing.jpg> What exactly are the reasons for this. Link to comment Share on other sites More sharing options...
bobatkins Posted July 24, 2003 Share Posted July 24, 2003 The sun is very, very, very bright. Link to comment Share on other sites More sharing options...
oskar_ojala Posted July 24, 2003 Share Posted July 24, 2003 Flare. Sun is just outside frame, the lens elements get many reflections and the contrast is too great for the CCD to handle, resulting in blooming. Solution: re-compose and/or use a lens hood. Note that the situation is a torture test for any lens, but the purple glow is particularly bad here. Link to comment Share on other sites More sharing options...
peter nelson Posted July 24, 2003 Share Posted July 24, 2003 Lots of things get called "chromatic aberration" in digicams (and fim ones, too) that aren't.<P> Chromatic aberration is when the lens focusses long wavelengths to a different point than short wavelengths. There are two reasons why the above doesn't look like CA to me:<P> 1. In true CA the long or short wavelenth component is still FOCUSSED , but its focus-point is just displaced. In the example you posted the magenta region is smeared over 2/3's of the frame.<P> 2. CA usually produces red or blue fringes, not magenta ones.<P> I think what you're showing us is simple lens flare resulting from a cheap, low-quality zoom lens. Lens flare often comes in weird colors like magenta, yellow, or green, because the optical coatings designed to prevent it are designed to PASS all wavelengths evenly, but don't necessarily REFLECT all wavelengths evenly. For example MgF2 (magnesium fluoride), which is a common lens coating, has a purplish reflection, which may be what you're seeing in the above image. Link to comment Share on other sites More sharing options...
gib Posted July 24, 2003 Share Posted July 24, 2003 did the aliens let you aboard their ship? Link to comment Share on other sites More sharing options...
stanley_rogouski Posted July 24, 2003 Author Share Posted July 24, 2003 <p>20 Seconds later, same place. </p> <p><img src=http://rogouski.net/loose-photos/graveyard.jpg></p> Link to comment Share on other sites More sharing options...
J.W. Wall Posted July 24, 2003 Share Posted July 24, 2003 It's because you're in a graveyard! Link to comment Share on other sites More sharing options...
bobatkins Posted July 24, 2003 Share Posted July 24, 2003 You zoomed. That's not fair. Link to comment Share on other sites More sharing options...
carl smith Posted July 24, 2003 Share Posted July 24, 2003 don't burn out your sensor in response to bob: "Waaaaaaaaaaaaaaaaaaaaaaaaahhhhhhhhhhhh!!!" Link to comment Share on other sites More sharing options...
lex_jenkins Posted July 27, 2003 Share Posted July 27, 2003 Yup, what other folks said. It's a combination of lens flare and sensor blooming. You'll get the same effect, on a smaller scale, by photographing a light bulb. Enlarge the image and study the bulb carefully - you'll see magenta fringing around the light source caused by the sensor going wacko. Link to comment Share on other sites More sharing options...
gsbhasin Posted July 29, 2003 Share Posted July 29, 2003 dude u are shooting right on to the sun/ this behavior is not unexpected at all/this would also damage your sensor since direct exposure to sun might yield a larger current at the photosites and burn up the sensor/ <p>anyways even regular pro zooms are not made to be shot directly at the sun. Link to comment Share on other sites More sharing options...
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