Originally posted by Blue Both versions are FF and can be used on film or digital. The EX had improved optical design with floating mechanism to control aberrations and coatings as well. The DG supposedly is specially coated to get the best color balance whilst cutting down flare and ghost caused by digital SLR cameras.
Thing that I don't quite understand is that when I read about the EX designation only, it already does this. I wonder if there is really any difference and Sigma forgot to emphasize the digital performance in original literature with the the EX version.
Edit: If the lens wasn't full format, it would be designated as EX DC rather than EX DG.
Maybe the DG version has coatings on the outside (back) of the rear element
to cut down on flare caused by reflection off the sensor itself. I think that's one
thing that the Pentax made-for-digitals have. I don't know that it matters much,
though, to the images. It may be 99% marketing, and a way to move people
towards 'upgrade'.
Anyway, at $280 this lens is now about $170 less than the Viv S1 105, so
to me that looks like a pretty good deal.
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