[fstdslrkx]

On my LBA chart long tele was planned only in couple of years. Currently my longest lens is 55-300 +1.4 vivitar.
The plan was to go then either for Sigma 50-500 or Pentax A 400 + 1.7 AF adapter.
But last week i saw in a store locally used Sigma 170-500 for 420 $ and it kind of ignited the issue a bit earlier. From what i read, lens is soft on long end , but i found that i can get Pentax M 400 5.6 for same price but with shipping and taxes it will be little more eventually.
I know that it will be wiser to wait and save money for better lens but LBA is an illness and i am afraid i will cave in soon enough.
However the question is what lens should give more keeper photos at longer end - soft but AF 170-500 Sigma or OK but manual (until affordable 1.7 AF and money for it will be found together) 400mm + 1.4. I intend to shoot birds ,Moon and occasional airshow/fireworks - usual novice stuff.
Will appreciate any input.
Alex.

[Adam]

For moon and fireworks, the M would probably be a better choice, but it's out of the question for action photography. Go with the Sigma, as that's a pretty good price!

[Dma110]

I've got the Sigma 170-500. Heres a some shots with it

[fstdslrkx]

Thank you both for replies. Dma110 - good shots, especially last one - beautiful. Sigma it is then. Probably .