Shake reduction on "old" lenses

hiya,

I'm using a Pentax-a smc 24-50mm f4 on my K20D. Will probably consider buying fancier lenses at a later stage (like the 16-50mm f2..

Anyway, I'm not sure how to set the Shake Reduction function with a zoom: would it be a good idea to select the actual focal length each time before taking a photo? Or is it enough to set it at a fixed value (which one? 24? 50?)?

Either way, I suppose I should choose the actual focal length (say 24 = 36, so I'll input 35 in the camera settings), correct?

Ideally set the SR to the length you are using. If that is inconvenient the advice tends to be to set the SR setting to the shortest of your zoom range. If you set to the longest it will over compensate and give you blur.

You should use the actual focal length of the lens in question. You have a 24mm lens at its widest so you input 24 (NOT 35 !!!). Focal length relates only to the lens, not to whatever digital/35mm/medium format camera it was designed for.

Thanks Peter.