Question
I am not a professional photographer, but I do make many product photos for the company I work for. For this I use Canon 400D with two external flash devices Walimex CY-600K.
I've noticed an interesting effect on many of the photos I take with white background. On the resulting image there is a red/blue area visible between object and the background. The effect is strongest for black objects and also seems too decrease when I make a brighter photo. It is mostly visible only if zoomed in really close and is not a real problem for me as the resolution is quite high and the resulting images are only 500px wide.
I am just curious as to what is causing it exactly.
For the following example photo I used manual mode with these settings: 1/200 F10 ISO200:
Can't post images yet, so here is a link: photo.
You can see blue area left from the object and red area right from it. What is causing this?
(not really sure which tag to give this..)
Answer
This is called Chromatic Aberration (CA). In photography its is also known as Purple Fringing. It occurs because lenses have a different refractive index for different wavelengths of light. The refractive index decreases with increasing wavelength. Its most visible when you shoot a dark object against a bright background.
To overcome this problem totally, you'll need to use a better optics/lens. Some lenses have very good control over CA, others do not. You did not mention what lens you are using on your 400D, but I assume its the 18-55mm kit that comes along. If you're not ready to purchase a new lens, I'd suggest shooting in RAW format, and use the Canon's Digital Photo Professional software which have the ability to fix CA issues mostly if not completely in post processing.
As long as you are not doing professional product photography or making large prints, I wouldn't want to spend thousands of dollar for a better lens as you've mentioned you re-size the image to a smaller size.
Check more discussion of this question.
No comments:
Post a Comment