Posted by David Ruether on 12/21/07 15:18

"Spex" <No.spam@ta.com> wrote in message
news:13mnl5ed2rmie38@corp.supernews.com...
> Steve King wrote:
>> "David Ruether" <xxx> wrote in message
>> news:476af1cb$0$11001$4c368faf@roadrunner.com...

>>> Canon certainly got their act together on this one
[...]
>>> --DR

>> Okay. I'll admit that I am not much of a techy, when it comes to
>> photography and lenses. So, I had to look up 'WA'. Google is >> my
>> friend: Cocaine Anonymous, or a virus solution, or the state of >>
>> California, or Chartered Accountant, or Certificate Authority, or >>
>> Computer Associates, or the chemical symbol for Calcium. I think I'll go
>> with calcium. Grrrrrrrr!
>>
>> Steve King

I guess I assumed that common-usage of WA for "wide-angle"
and CA for "chromatic aberation" in this NG (ah, "news group"...;-)would
save space - only to find that a transferred single-spaced
Word doc. became a double-spaced post...;-(

> I think you meant CA not WA
>
> Chromatic Aberration.
>
> Around contrasty areas you'll see green and purple or blue and red lines
> caused by the refracting at different wavelengths. It has always been
> there just not as obvious in the low res world of SD.
>
> Lens can be coated to reduce this but it can lead to ugly bokeh if the
> lens is over optimised.

It is a lens design (or alignment fault) characteristic, not a matter
of coatings...

> I believe the new Sony EX1 actually corrects CA in the DSP which is
> another completely valid way of reducing its appearance. I can also be
> fixed in post by rescaling the R,G&B components.

Yes - neat!

> The standard Canon XL-H1 lens was the worst offender I've ever > seen for
> CA.

The original Canon XL-1 lens was no "gem", either, good as some
Canon lenses can be...
--DR

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