which lens would be better

I recently purchased a 5D (if you can call March recent) and I just got the Sony 75-300mm Telephoto as a gift, but I was leaning towords the Tamron 70-300mm LD Di Macro Telephoto http://www.tamron.com/lenses/prod/70300_di_a017.asp

I was wondering if any body has had experience with these lenses and could give me their opinions, as I am thinking of returning the Sony infavor of the Tamron. Any insight would be greatly appreciated.
Thank you.

Personally, I wouldn't go through the trouble as I think it's more a lateral move rather than an upgrade.

Thomas

If I was going to swap. it would be for the Tamron 28-300 from Cameta Camera.

Although I don't have any experience with either, I would rely that Sony's lens is a good one. It's probably a rebadged version of Minolta's and most Minolta lenses outperform 3rd party lenses - broadly speaking. Unless you step up to the Tamron - AF 70-210 F2.8 SP LD (which is very expensive and discontinued), the lens you have will be a close or better performer than the Tamron you're looking at. Think Konica Minolta 28-75 2.8 D (for its incredible sharpness) or a wide angle such as Sigma 10-20mm, Tamron 11-18mm as a 2nd or 3rd lens and you'll be better off. That way you'll have less overlap.

i got that tamron, but the non-Di version.

AF is so slow and unreliable so i can only use MF

image is soft, very very soft, u'll disgusted with its quality

But have not experienced the Di version though...