Sigma 50-500 vs 150-500 vs 170-500

[SwissJon]

Been looking for a while for a long zoom lens. I'm tempted by the Bigma 50-500, but the 150-500 has OS and the 170-500 is significantly cheaper..

PersonallyI think that at these lengths, I'm going to need OS, but that's twice the price of the Bigma, and the Bigma has 10x zoom..

What are your thoughts? Which would you choose and why? I'm looking to soot the moon as well as some details in a landscape, possibly picking out animals, however I'm NOT a birder.

[BuddhaPi]

Hey Jon, I have the Sigma 150-500, I'm happy with it, but would have preferred to get the nikon 400, for me it was purely a $$ decision as I was able to get the siggy brand new for the cost of shipping, If I had the money to lay down I would have went with the nikon/nikkor glass