what's the difference????

dbaker1221

if I buy a used 50-500 sigma or a new 50-500 sigma DG? other than one's new, & will cost me 300 or so more.

the more I try to figure out what lens to buy on my 1000 or a bit more budget the more my brain turns to mudd!!!!!!!!!!:scratch

Scott_Quier

The difference, as I understand it, is that the newer ones are designed to work better with digital sensors. This is done in at least two ways:

• Modifiy the optics to force the light rays to hit perpendicular to the surface of the sensor. Did they do this with the BigMa? I don't know, but I doubt it.
• Another thing I have heard is that they use different coatings on the rear element of the lens to cut down on the amount of light that is reflected off that element and back onto the sensor. This wasn't such an issue with film as the film surface was/is not very reflective. The sensor is covered by a piece of glass that is all smoooooth and can/will reflect more light than will a similar sized piece of film.

Are there other ways to make "digital" lenses different from "film" lenses? Probably, but these are two that I know about.

dlibrach

I bought a used non-DG "Bigma" last year to go with my 20D and have had no problems. I did a lot of research and could find no tests that could show any quality difference in the images between the DG and non-DG w/ a DSLR.

DG is supposed to provide an extra coating (or a different coating) that helps reduce glare that can sometimes be found on digital sensors. However, I've never had a problem. I think it was more of a way for Sigma to market a new upgrade of their lens without having to totally re-do it. I use the hood all the time and although it's hard to make one that is perfect for such a large focal range, it does it's job.

I would go ahead and save a few $ and get the non-DG. You won't regret your purchase.

Cheers,
D