Common sense would say to try before buying. I have heard so many mixed opinions on the Sigma 150-500 that I don't really know what to do either. If you think you will only need to use 400-450mm at the longest, with enough light to enable at least f8, you will probably be OK. A rock solid tripod will help a great deal without OS. From what I gather, the 50-500 OS is the one to go for. If you are buying for Nikon, I would say to get the 300mm f4 and a 1.4 TC.
I've heard those stories too.I guess good jugdement clouded by good price.lol Thanks.common sense would say to try before buying. i have heard so many mixed opinions on the sigma 150-500 that i dont really know what to do either. if you think you will only need to use 400-450mm at the longest, with enough light to enable at least f8, you will probably be ok. a rock solid tripod will help a great deal without os. from what i gather,the 50-500 os is the one to go for. if you are buying for nikon, i would say to get the 300mm f4 and a 1.4 TC.