Originally Posted by Gobigorgohome
Yes, I understand. For most situations the Sigma 150-500mm would be enough anyways ... yes, I read about the lightning too at the review I posted in my last post, it seemed that they could not zoom in max with a 100-400mm lens either, so it would not have been optimal for the 150-500mm either way.
Most people are excited about long lenses, but the tough truth is long lenses = bigger lenses = more glass, which also means beefier lens body to support it = harder to design and build cheaply.
It gets expensive, even for not "amazing" lenses.
TC's won't help you much unless the starting point is already very good : e.g. good 2x TC on a 70-200 2.8 or 300 2.8 = viable option. 1.4x TCs on good f/4~5.6 lenses (mostly primes) are also ok.
Most people that are excited about long lenses etc, usually get to shoot them once a year to so on some vacation trip.
My take would be to get a xx-400 / or xx-500 used & relatively cheap, "test the waters" and see if you will get enough usage out of it or it is just the excitement of a "what if" and "G.A.S."
After a few months you will know if that is something you want to pursue further, and ofc you will know that there is little you can do other than dropping some serious cash for you to get something considerably better.
No silver bullet on this one.Edited by pcfoo - 1/13/15 at 12:50pm