SIGMA 50-500 "old" vs "new"

Dear all,
Who has any “comparative experience” with the SIGMA 50-500 “BIGMA” Zoom “old vs. new”.
My question in particular: Is it worthwhile to up-grade from the older non HSM version to the new one?
What advantages are there - if any ??
I’ve got the K-5 and have the older BIGMA and I’m contemplating this up-grade.

(OPTION: Are there any alternatives - I also do occasional videos, so the usual cropping would be rather difficult...)

Thanks for any feedback – or helpful links, if this topic was discussed elsewhere before

Regards

Urs

I had the old one and now have the new.

The OS version supposedly has better optics but to be honest I have found very little in it. I got some great shots on the old one at 500mm and get the same on the new version. The main differences are HSM and OS (and when I compare Pentax SR to Sigmas OS there is no real benefit apart from a stable image in the viewfinder).

Personally, knowing what I know now I probably wouldn't bother.

Mike,

Thanks - Looks like I might hang on to old one

Urs

Strange...

I've been fortunate to try all the Sigmas (old and new) and still maintain the 150 500 to be much sharper.

Just my two cents

QuestionableCarrot,

just had a look at some of your photos on your homepage:
EXCELLENT stuff - congrats !

Urs

I've owned both the 50-500 and the 150-500 and I agree 100% with Alistair's comments above. The 150-500 is miles sharper at all focal lengths than the 50-500. Of course, that could just be down to the copy of the 50-500 I had, but I can only base my findings on my own experiences. The 50-500 was the 'old' one and my current 150-500 is the non-OS version.

Regards
David