Experts - Question about CA

[DECHUSA]

http://s91227504.onlinehome.us/tamr24135.jpg

Above is a 2X enlarged crop of a pic taken with the Tamron 24-135. (Nikon D50 at 24mm f11) It is from the upper left corner of the pic. It is from this gallery:

http://gerryd.smugmug.com/gallery/1351289

(thanks to Gerryd for the pic)

IMHO, this is an unacceptable amount of CA, but this degree of CA only appears in this one pic in this gallery. There are other pics of similar objects at similar exposure levels and focal lengths that have much MUCH less CA.

Why could this be the case?

Should this one pic cause me to worry that CA might be an inherent problem with this lens, or should I consider it an aberration? ( I would be using the lens on a 20D, and plan to buy a 1D MKII )

THANKS

Best regards,

Steven

[FlashZebra]

Stephen,

I am not an expert.

But, read this test report on the Tamron 24-135. It seems to have a marginal CA performance, expecially at the wide end.

So, it seems that you can expect CA if you use this lens at the wide end under conditions that tend to promote CA.

See:

http://www.photozone.de/8Reviews/lenses/tamron_24135_3556/index.htm

Enjoy! Lon