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RF 24-105 F4L horrible purple fringing

Started Apr 28, 2021 | Discussions thread
Tristimulus Veteran Member • Posts: 9,998
Re: I think you may be expecting too much out of the lens

Karl_Guttag wrote:

phatgreatwall wrote:

thanks for all the info. i downloaded a trial of DXO and it works like magic. DPP/Luminar could not completely eliminate it, which is surprising since DPP is supposed to be Canon's official software that covers their lens flaws. also the fact that an L lens exhibits such bad purple fringing is a shocker, i would've thought L for the price would be at least better than my iphone.

I'm not an expert on this, but my understanding is that purple fringing is largely due to the UV light getting to the sensor (see: https://en.wikipedia.org/wiki/Purple_fringing). UV light is out of the range of wavelengths for which the lenses are designed, but which the camera ends up detecting as purple.

UV light does not reach the image sensor at all. Cameras have UV and IR block filters over the image sensor.

Purple fringing is caused by dispersion. Red or blue light is slightly out of focus.

Even people with very high-end lenses will get purple fringe in the right conditions. It turns out the overcast days have a lot of UV light which makes the problem worse.

Nope.

But get some branches closer than the focus point towards the corners of the image. Add a large aperture. Then you will provoke purple fringing most effectively.

In the cases where purple fringing becomes seriously bad, it can be easily removed.

Yes.

But you may not want to process it out all the time due to the computational effort and time and the risk of damaging something else in the image.

Nope. Just remove secondary chromatic aberration in post processing without fear! 

Longitudinal chromatic aberration however is rather pesky.

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