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LL & DxO open letter : wide aperture lenses & light transmission
#40
[quote name='Brightcolours' timestamp='1291470806' post='4755']

If different colours have different focus planes, it may well be that AF systems are made to be more receptive to green in order to get the best results for us, the viewers of the results. Of course, black and white are not colours of light, so the same applies.



PF and LoCA are NOT the same thing. LoCA is green and magenta.

PF is purple to blue-ish (usually, it can also appear towards red oddly enough).

Nice PF example from the Sony 16mm f2.8 fisheye:



[/quote]

This is actually LA, maybe enhanced a little by PF due to the extremely high contrast transitions, but definitely lateral colour aberrations: green on one edge, purple and blue on the opposite edge.

Quote:PF in lovely "orbs":

[Image: 682px-Coma_and_chromatic_aberration.jpg]
Yep, PF
Quote:PF like we know it from compact digitals:

Nope, lateral colour aberrations again. Check the green fringing on the opposite edges to the blue ones.
Quote:Longitudinal Chromatic Aberration:



LoCA from Canon EF 100mm f2.8mm macro:





Photosites do not "react" to eachother,

Actually, they do, from an electronic POV. The charge in one may affect the charge or relative charge in the surrounding ones. This is why there was a black pixel phenomenon, f.e., early on with the 5D II.

Quote:LoCA is lens dependent. PF is lens dependent too, and seen mostly with cheaper compact digital cameras. Manufacturers have made changes in back element coating to combat PF, Sigma has introduced the DG(DC) line and Tazmron the Di(Di II) line specifically for PF (not LoCa). Nowadays you do not see PF very often anymore.

You still see it a lot. IMO it is not only lens dependent, but also sensor assembly dependent. I reckon that reflections internally to the filter assembly on top of the sensor, which as we all know in effect is a half-mirror, may also contribute to fringing effects. AFAIK, even the AA-filter itself may contribute to these effects.

Quote:You do see a lot of LoCA still, specifically with wide aperture lenses and macro lenses.

Not that often with macro lenses. Normally, lenses with relatively long tubes and smaller apertures show virtually no LoCa. There are exceptions, of course, but from my experience macro lenses have relatively few problems with LoCa.

Quote:LaCA ("normal" CA) is mostly seen with standard zooms and wide lenses, but also with other lenses. Some brands show laCA more (often) than others (Nikon, Tokina, Pentax come to mind).

Don't forget Sigma, especially their wides. The 12-24 EX is a prime example for LA (of the blue-green variety).



Kind regards, Wim



P.S.: Could not quote all of your images, unfortunately. The reply editor didn't let me.
Gear: Canon EOS R with 3 primes and 2 zooms, 4 EF-R adapters, Canon EOS 5 (analog), 9 Canon EF primes, a lone Canon EF zoom, 2 extenders, 2 converters, tubes; Olympus OM-D 1 Mk II & Pen F with 12 primes, 6 zooms, and 3 Metabones EF-MFT adapters ....
  


Messages In This Thread
LL & DxO open letter : wide aperture lenses & light transmission - by genotypewriter - 11-30-2010, 11:41 PM
LL & DxO open letter : wide aperture lenses & light transmission - by genotypewriter - 12-01-2010, 12:17 AM
LL & DxO open letter : wide aperture lenses & light transmission - by genotypewriter - 12-01-2010, 10:53 PM
LL & DxO open letter : wide aperture lenses & light transmission - by genotypewriter - 12-03-2010, 04:10 AM
LL & DxO open letter : wide aperture lenses & light transmission - by genotypewriter - 12-03-2010, 10:52 AM
LL & DxO open letter : wide aperture lenses & light transmission - by genotypewriter - 12-04-2010, 03:51 AM
LL & DxO open letter : wide aperture lenses & light transmission - by genotypewriter - 12-04-2010, 04:03 AM
LL & DxO open letter : wide aperture lenses & light transmission - by wim - 12-05-2010, 05:45 PM
LL & DxO open letter : wide aperture lenses & light transmission - by genotypewriter - 12-06-2010, 04:34 AM
LL & DxO open letter : wide aperture lenses & light transmission - by genotypewriter - 12-06-2010, 04:38 AM
LL & DxO open letter : wide aperture lenses & light transmission - by genotypewriter - 12-06-2010, 05:09 AM
LL & DxO open letter : wide aperture lenses & light transmission - by genotypewriter - 12-06-2010, 11:42 PM
LL & DxO open letter : wide aperture lenses & light transmission - by genotypewriter - 12-08-2010, 03:22 AM

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