Occurrence CA on my 'L'

[20dster]

Own this 16-35 'L', recently doing some outdoor snapshot and shockly saw some photo gotCA... Is't normal even for those expensive 'L' glass? Or i may send to Canon sc for calibrated?

[Canew]

AFAIK, CA cannot be corrected by calibration.

[Belle&Sebastain]

almost of my L lenses got CA, 24mm, 24-70mm, 17-35mm

most of my primes got CA, 50mm, 35mm, 45mm, 90mm

[user12343]

i tink canon never really explicitly says that CAs are completely eliminated with their flagship L-series. rather, i would think that such artifacts are well-controlled and reduced to the minimum possible magnitude.

simple laws of physics, there can never be a perfect lens that all wavelengths of visible light spectrum converge into one focal point

[solarii]

CA is common is lenses... the measure of quality is how well controlled it is. Under high contrast conditions its usually there...just how obvious the fringing is. There's nothing calibration can do... its the characteristic of the lens and its design.

[+evenstar]

even my 24-70 has CA esp when shooting a subject with strong lighting behind

[Jemapela]

If I'm not wrong, CA is more apparent (visible) with digital cameras but less with film.

[kuoann]

"Chromatic Abberation" is a basic phenomenon of optics, as the lens acts like a prism.
The main processs involved in its productions are:

1. Refraction --> 2. Dispersion



Because of this, you will notice that:
1. CA becomes more pronounced the further you go from the center of the lens. (Because the light is incident at a greater angle to the lens.)

2. Blue will be nearer the center of the lens than red. (Because blue light is bent towards the center of the lens more than the red)

And that's all I remember from my "O" level physics (which is 20yrs ago!)

Because lenses work by refraction, and because refraction disperses light, you will find that even L lenses show CA to a greater or lesser degree.

[user12343]

great refresher course

Originally Posted by kuoann "Chromatic Abberation" is a basic phenomenon of optics, as the lens acts like a prism. The main processs involved in its productions are: 1. Refraction --> 2. Dispersion Because of this, you will notice that: 1. CA becomes more pronounced the further you go from the center of the lens. (Because the light is incident at a greater angle to the lens.) 2. Blue will be nearer the center of the lens than red. (Because blue light is bent towards the center of the lens more than the red) And that's all I remember from my "O" level physics (which is 20yrs ago!) Because lenses work by refraction, and because refraction disperses light, you will find that even L lenses show CA to a greater or lesser degree.

[kuoann]

CA is apparent when there is bright light next to a dark area because the dispersion of light at varying angles results in some of that disperesed light refracted into the dark area where it is more easily visible.

The reason why we are noticing CA more in the digital era is because: we blow up the pictures to 100% magnification onscreen and view pictures in greater detail. When was the last time you blew up a 35mm exposure to poster size?

[lynch]

That's also the reason why hoods are a must!

[+evenstar]

does hood affect this?

[solarii]

Originally Posted by +evenstar does hood affect this?

No. Hoods reduce flaring. Nothing to do with CA. If you've seen how and where CA occurs, you'll know that hoods have no effect.

The only way you can reduce CA, other than switching lenses, is to recompose so you don't have any high contrast edges in yr frame, which is pretty ridiculous in practical terms.

[+evenstar]

Originally Posted by solarii No. Hoods reduce flaring. Nothing to do with CA. If you've seen how and where CA occurs, you'll know that hoods have no effect.

yes i know that...it was a counter to the post by lynch, "That's also the reason why hoods are a must!"

[haagen_dazs]

in my opinion, all canon's L wide angle lenes are not very good.
Unfortunately, due to the design, the lens will always suffer from CA and some degree of distortion. I never liked the WA L lens. I have used them and have been disappointed, sad to say.

If you have the interest, you should try to check out those alternative wide angle lenses by carl zeiss (contax mount), leica or zuiko.

The CZ lens are amazing. Almost absolutely no CA. I have done tests to know this.

[solarii]

Originally Posted by +evenstar yes i know that...it was a counter to the post by lynch, "That's also the reason why hoods are a must!"

Ah a rhetoric qn.

That's the bloody problem with forums... its sometimes hard to tell if its an innocent query or rhetoric qn.

[freelancer]

Originally Posted by 20dster Own this 16-35 'L', recently doing some outdoor snapshot and shockly saw some photo gotCA... Is't normal even for those expensive 'L' glass? Or i may send to Canon sc for calibrated?

CA can be corrected in photoshop .. there are some actions that get this done very nicely.

Or if you shoot RAW, some software like RSP automatically correct for CA during the conversion to TIFF or JPEG.

[Garion]

One possible solution (tho may not be the most effective) to reduce CA is stop down the lens, I've noticed even for some Canon 'L' lens, especially wide angle to mide range zoom, there is some CA apparent under certain lighting conditions when shot wide open. Stop down a stop or two or more and the CA is diminished greatly. Different lens have varying effects with regards to this technique of reducing CA, some may still exhibit more CA than others.

[sehsuan]

Originally Posted by 20dster Own this 16-35 'L', recently doing some outdoor snapshot and shockly saw some photo gotCA... Is't normal even for those expensive 'L' glass? Or i may send to Canon sc for calibrated?

Post an image with a 100% crop, and let's see how bad it goes.

Remember, we are not working as lens reviewers, so if the level is decent, just go on.

[haagen_dazs]

Originally Posted by freelancer CA can be corrected in photoshop .. there are some actions that get this done very nicely. Or if you shoot RAW, some software like RSP automatically correct for CA during the conversion to TIFF or JPEG.

point to note is that you can fix it but you just cannot retrieve the lost details in the photo.