500mm Lens

I was considering effort a sigma 50-500mm lense from ebay for a substantially cheaper toll than normal. I am wondering if there is anything I should be hunting for in this lense that would attain it nonfunctional or flawed.

Hey, Just a hurried un-boxing recording fro the Sigma 150-500mm lense with a whatever prototypal impressions. Pictures to study erst I’ve had a quantity to intend discover and verify some. … sigma 150 500 0001

I hit a Pentax 50mm lens, a Sigma 70 - 200mm and a Sigma 500mm lens. They are every drill focus. I conceive the mounting identify is a Pentax K increase (bayonet fitting). Could I ingest them with the Pentax ist or somthing similar?