[genotypewriter]

[quote name='Brightcolours' timestamp='1291470806' post='4755']

Photosites do not "react" to eachother,

[/quote]

Can't remember saying that they did <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/wink.gif' class='bbc_emoticon' alt='' />



[quote name='Brightcolours' timestamp='1291470806' post='4755']

LoCA is lens dependent. PF is lens dependent too

[/quote]

Can't remember not saying these too <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/wink.gif' class='bbc_emoticon' alt='' />





GTW

[genotypewriter]

deleted

[genotypewriter]

[quote name='wim' timestamp='1291571116' post='4775']

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

[/quote]

Wim, I see you're really bitter about your bad experience with the 12-24 <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='' />



Actually, most people seem to say that it is a bad lens... but I've seen sample shots and tests by people that suggests there are some good samples out there (especially in regard to CA)... however rare they may be:



http://pikespeakphoto.com/tests/sigmalens12-24.htm

http://www.juzaphoto.com/eng/articles/si...review.htm



There was a similar claim on 16-9.net about the original 24L.



GTW

[wim]

<img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='' />

[quote name='genotypewriter' timestamp='1291612148' post='4783']

Wim, I see you're really bitter about your bad experience with the 12-24 <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='' />



Actually, most people seem to say that it is a bad lens... but I've seen sample shots and tests by people that suggests there are some good samples out there (especially in regard to CA)... however rare they may be:



[url="http://pikespeakphoto.com/tests/sigmalens12-24.htm"]http://pikespeakphot...malens12-24.htm[/url]

[url="http://www.juzaphoto.com/eng/articles/sigma_12-24_review.htm"]http://www.juzaphoto...2-24_review.htm[/url]



There was a similar claim on 16-9.net about the original 24L.



GTW

[/quote]

Geno,



Even in Juza's winter landscape shot you can see the blurred details in the corners, even at this small magnification. Look at the crystals in the granite boulders - they are smeared, even if maybe not as bad as with the lens specimens I experienced <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='' />.



BTW, the original 24L was declared the #1 lens in its class at 16-9.net originally <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='' />.



Kind regards, Wim

[genotypewriter]

[quote name='wim' timestamp='1291669257' post='4796']

Even in Juza's winter landscape shot you can see the blurred details in the corners, even at this small magnification. Look at the crystals in the granite boulders - they are smeared, even if maybe not as bad as with the lens specimens I experienced <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='' />.

[/quote]

I certainly don't think Juza got one of the best samples of the lens but he certainly didn't get one that deserves the sort of bashing that it gets from most reviews... especially when considering that this is the only lens giving this field of view and with zero distortion too.



If you look at the other link, only around the 21mm mark on the frame radius it looks a bit dodgy... I have a feeling that there could be some strong field curvature there because I see a diagonal line being sharp across the crop, instead of the total smear it should be. If you look at Juza's neighbourhood shot corner crops, you don't see this kind of smearing, possibly because there's enough DOF at that distance.





[quote name='wim' timestamp='1291669257' post='4796']

BTW, the original 24L was declared the #1 lens in its class at 16-9.net originally <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='' />.

[/quote]

Yes, I remember them stating that their sample was quite different from what other online review sites got a hold of.





What I can't say is how many samples one needs to go through before they get a good one <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='' />



GTW

[Brightcolours]

[quote name='wim' timestamp='1291571116' post='4775']

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. [color="#FF0000"]*1[/color]

Yep, PF

Nope, lateral colour aberrations again. Check the green fringing on the opposite edges to the blue ones.[color="#FF0000"]*2[/color]

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.[color="#FF0000"]*3[/color]



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.[color="#FF0000"]*4[/color]



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.[color="#FF0000"]*5[/color]



Don't forget Sigma, especially their wides. The 12-24 EX is a prime example for LA (of the blue-green variety).[color="#FF0000"]*6[/color]



Kind regards, Wim



P.S.: Could not quote all of your images, unfortunately. The reply editor didn't let me.

[/quote]

[color="#FF0000"]*1[/color]: Yes, I already noted myself that that Sony 16mm sample was no PF but "normal' CA.



[color="#FF0000"]*2[/color]: No, I do not see that at all. I see a blue very wide "fringe/bleed" and NO yellow wide bleed on the other side of the dark leafs into the white, which should be there when it is CA. PF I say.



[color="#FF0000"]*3[/color]: I think that is a strange wrong way of explaining what was the matter with the 5D mk II black spots. It was NOT the sensels influencing the neighboring voltages.... It was an error in DA conversion in certain specific cases, a software error basically. Where totally "full" was written as totally "empty".



[color="#FF0000"]*4[/color]: It is not "sensor dependent", really, even though the sensor may have to do with it occurring because of reflecting light. It does not matter which sensor a camera has, and as such it is not sensor dependent. It is however lens dependent... some lenses of a certain focal length and a certain aperture may show it, where in the exact same conditions an other lens with same focal length and aperture do not show it. Lens/camera manufacturers know the actual reason for PF... just of of the (many) things that keep on being speculated about on the internet, like AF. I think that the reason given for PF a few years ago (when it was still very apparent/prolific in compact digitals) has probably some truth to it, even though that reason gets snowed under in forums where PF gets to be called "LoCA" even when it is clearly not LoCA: The back element of the lens, its shape and coatings. Which may reflect light back to the sensor (light the sensor reflected). But it is hard to verify.



[color="#FF0000"]*5[/color]: Take just about ANY macro lens and shoot wide open, up close, in an angle, letters from a book. Or metal with specular highlights. You will see LoCA. I do not know how many times I have seen that occurring with people in forums, and them wondering if they had a "bad sample" of a lens (they do not) because of heavy "CA".

I know the Canon 100mm f2.8 USM macro shows very clear magenta & green LoCA. I know the Tamron 90mm f2.8 macro gives very clear magenta & green LoCA. I have seen it with the 105mm Nikon, and the Zeiss 100mm f2 macro.

Of course, you might not notice it because you use your macro lenses maybe only closed down. But LoCA they do show.



[color="#FF0000"]*6[/color]: I will forget Sigma, in this instance. I am sure, Sigma makes some lenses that show stronger CA than one would expect, but not as a general rule. The lens manufacturers I did mention do seem to have stronger CA in many models from many types of lenses, from primes, to UWA zooms to standard zooms to tele lenses and macro lenses.

[Sylvain]

Guys, I've been vaguely following the thread shift to a CA,PF & LoCA discussion. Are we still within the initial topic? I usually don't mind the usual digression but looks a bit far off now?



Greetings,

S.

[genotypewriter]

[quote name='Sylvain' timestamp='1291745071' post='4845']

Guys, I've been vaguely following the thread shift to a CA,PF & LoCA discussion.

[/quote]

Speak for yourself... I've seen this thread shift to a CA, PF, LoCA, forum-courtesy & finally a forum-philosophy discussion ;D



But yeah... guilty as charged...



GTW