I recently bought a Sigma 70-300mm Macro Telephoto Lens: ...and now I got a Nikon Vivitar Series 1 70-210mm Macro Focusing Telephoto Lens to compare them side-by-side: At the end, only one can survive -- the other is off to eBay. --The specs-- Focal Ranges Sigma: 70-300mm Nikon: 70-210mm Aperture Sigma: f/4-5.6 Nikon: f/3.5 Magnification Ratio Thingamabob Sigma: 1:2 at 300mm (for comparison, 1:2.9 at 210mm) Nikon: 1:3.5 Weight Sigma: 19 oz Nikon: at least 7 tons (but closer to 30 oz) --Nikon "Yay"s-- The Vivitar is a LOT sturdier than the Sigma. I'm pretty sure it's build out of pure lead and uses plutonium for the glass. I'm convinced could roundhouse kick this thing onto oncoming traffic and it wouldn't break. It's also a faster lens than the Sigma. Considerably faster at the max focal length (over 2 stops). --Nikon "Aww"s-- Biggest aww about the Vivitar is that it doesn't do anything automatically with my CVS Powerflash. No autofocusing, no aperture control; therefore, it only works in Manual mode. Not-so-bad when you're working in a controlled environment, but very annoying when you would rather be on Aperture Priority and can't necessarily mess around with different shutter speeds. Second biggest aww about the Vivitar is the magnification ratio thingamabob. See pictures below to see what I'm talking about. --Test Pictures-- Nothing too fancy, just a few test shots... Nikon at 210mm f/3.5: Sigma at 210 f/5.6: ...but because of the bigger focal range and smaller magnification ratio thingamabob, I can get a lot closer with the Sigma (here, at 300mm f/5.6): Nikon at 210mm: Sigma at 210mm: Again, Sigma at 300mm: Nikon's bokeh: Sigma's bokeh: Possibly the ugliest photo I've ever taken... ...with the Nikon at 70mm: ...with the Sigma at 70mm: Therefore, even though I like the colors on the Nikon better, I believe that the Sigma wins! It's a beast at autofocusing, it does macros a whole lot better, it has a better focal range, it's newer... Don't get me wrong, the Nikon Vivitar is still an awesome lens -- but the Sigma's better IMHO. C&C's?