Ian Stuart Forsyth wrote:
If I was you I would at least think about picking up a body that one could purchase the HSM version of this lens as you do not save any money buying it pentax screw drive format. When dealing with lenses at this price point picking up a body that can get you the best out of what that beast has to offer would be my first priority. I am not speaking IQ wise but better AF performance as sigma has no HSM for pentax, I would not hesitate in shopping around. I know with the sigma 300 2.8 I had always felt as if sigma through it together as afterthought with screw drive just for pentax and this that lens was really designed as an HSM 300mm 2.8. I have no idea on the 500mm but I have the feeling this also applies.-- hide signature --
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As the 300 F2.8 was introduced in 1988 and the 500 f4.5 a year earlier in 1987 its your imagination, HSM is the 'afterthought' the lens were designed for screw drive.
Its easy to let one imagination cloud your view.
As to buying another body just to support a 500 f4.5 purchase in HSM that seems a reckless waste of money to me.
If you need the 500 in HSM and wont compromise with screw then sell up all your Pentax and purchase with-ever brand floats your boat.
Running two brands with similar controls will lead to the jack of all syndrome that we often see exemplified here. Never quite comfortable with the body in hand and not sure just what each body is capable of.