Sigma 'APO' Question.

[rockabillyrebel]

I notice on some of the Sigma lenses that the letters APO appear in the lens description, these particular lenses are also slightly more expensive than their non APO equivalents. Can anyone tell me what additional benefits I'd be getting if I bought a lens with this APO? Is it something to do with the glass & therefore image quality?

The lens I was looking at buying is the Sigma AF 70-300mm f/4-5.6 APO M/Super II for Canon.

Thanks for any help.

[kahfluie]

I have an APO lens ( 70-200 f/2.8 ) from sigma and it works great for me...

Taken from Sigma's website:

APO lenses. These lenses use apochromatic design and Special Low Dispersion glass (SLD) for minimum color aberration and ultimate telephoto image quality, improving contrast and sharpness.

Apochromatic (APO) telephoto lenses greatly minimize color aberration, a phenomenon created by different wave lengths of light refracting at different angles. This causes each color to have a slightly different imaging point, resulting in poor image quality.

APO Zoom Macros offer up to 1:2 magnification in the telephoto range with instant shifting from normal to macro shooting.

APO Tele-Macros offer 1:3 image size close focus, long thought to be impossible for a telephoto lens — and are no larger than a fixed focal lens of the same class.