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Chromatic Lens Aberration
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Dec 26, 2017, 19:24 #1
WDHewson Member ***
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I can't say that I understand lens aberration well.

But I've never seen a chromatic aberration like this one!!

Explanations are appreciated.  Thanks.


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Dec 27, 2017, 02:29 #2
EdMak Posting Freak *****
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Had a camera club member, 1950's, who frequently mentioned this, when critique was asked. I was 15/16, at the time.I looked it up in Ilford manual of photography, Xmas present, 1947. Memorized this, and spouted it when it was brought up by member asking exactly what it was. So from memory, forgotten now on what page.


In a lens showing chromatic aberration, differently coloured rays do not come to a common focus. It can be corrected by using, as a second component, a concave lens, in which the dispersion is equal, and opposite, to that produced by the first lens.

Ed. aka known as Lesley Welch, the memory man.

https://en.wikipedia.org/wiki/Leslie_Welch

To each his own!

Dec 27, 2017, 02:44 #3
MrB Posting Freak *****
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That looks like lens flare (not chromatic aberration), caused by a bright light source just outside the field of view. The stray light is reflected and refracted by surfaces inside the lens and reaches the sensor, producing odd coloured shapes in the image. It can be minimised by using a lens hood of the correct shape and size for the lens.

Cheers.
Philip

Dec 27, 2017, 09:13 #4
GrahamS Senior Member ****
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This is not chromatic aberration, although the underlying cause is similar. This is flare, caused by light from the sun, or reflected light from the sun striking the front element of the lens and being refracted from one element to another until the result strikes the image plane (sensor or film.) . Think of the front element as a curved prism.

GrahamS
Take my advice. I'm not using it.Wink


Dec 30, 2017, 05:32 #5
WDHewson Member ***
Status: Offline Posts:125 Threads:6 Joined:Nov 2013 Reputation: 2
Thanks guys.

Because of the color I was drawn to the chromatic explanation, and thought flare was white light.

Strange circular twist to the flare. Never seen anything like it.

Dec 30, 2017, 07:12 #6
EdMak Posting Freak *****
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CA is very subtle. B & W, it makes the image look slightly out of focus. Ed.

To each his own!


Jan 13, 2018, 20:04 #7
EnglishBob AKA Craig *****
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Lens flare there as others have said. Chromatic aberration typically forms along edges of subjects, typically where there is a strong difference in light levels.






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