what causes chromatic abberation?

[jann1033]

is it the only the particular lens or conditions as well as the lens...i am wondering this as i wonder if certain apertures, focal lengths etc would make it better

 

[0bli0]

chromatic aberation is caused by the lens not focussing all colour wavelengths at the same plane. but true CA is extremely rare. what you typically see is purple fringing - often where there is high contrast, such as branches with a sky background. it's very similar but it's a digital sensor characteristic caused by the tiny lenses that are on the sensor's surface. basically the bright light coming off the sky is focussed differently than the light from the branches - especially when the light is not hitting the sensor at a right angle.

this is one thing that makes a sensor completely different than film. a piece of film can take light coming from any angle. the microlenses are deisgned to take light at a relatively steep angle. this is why some cameras vignette with some lenses, yet the lens doesn't vignette on film. my r-d1, for example does this very noticeably due to the proximity of the lens (and the resultant light being directed toward the sensor). it will vignette a 28 mm lens but if i put the same lens on my film rangefinder, there is zero darkening.