Slains Castle

by pakman

submit your photo

Hall of Fame
View past winners from this year

Please participate in Meta
and help us grow.

Sign up ×
Photography Stack Exchange is a question and answer site for professional, enthusiast and amateur photographers. It's 100% free, no registration required.

What is Chromatic Aberration? Is it a physical part of the lens, or just an optical illusion?

share|improve this question

3 Answers 3

up vote 20 down vote accepted

Chromatic Aberration is a distortion that occurs when a lens focuses different colours slightly differently.

It is caused by the refractive index of the lens (the amount that the lens bends light) being slightly different for different colours, so I suppose you could say it is caused by physical properties of the lens. It is possible to produce higher quality lenses that exhibit this effect to a lesser extent.

Wikipedia has a very detailed article on chromatic aberration.

share|improve this answer

When light enters or exits glass at an angle, it bends. But the different colours in the light bend by a different amount.

Lenses try to correct for this by sandwiching together different densities of glass, but they have to take compromises - there's no such thing as perfect as it would compromise on something else.

So you may still see colour fringes, particularly at the edge of your frame (where the light hits your lens at a greater angle) in some conditions (typically high contrast). The colour fringes will often be blue (or purple-ish) as blue light bends (refracts) more than other colours. You may also see colour fringes in out of focus areas (bokeh). Different lens designs will show this up differently.

share|improve this answer

If you're trying to figure out how to identify it in your photos, it's that faint purple halo that appears. It's usually easy to spot when shooting a dark object against a bright background.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.