I am an astrophotographer and need a large aperture (at least f2., very sharp, 135mm lens, K or M42 fit. Pics of stars show up any lack of sharpness very easily. I see Pentax have made various 135's in the past - f2.5, f2.8 and rumoured, an A* SMC f1.8. Has anyone experience or advice for me as to which are the best ones to go for? Or are there other makes that are worth considering?

Thanks in advance. Mick

Matt

Many thanks for the URL - the information there gives a good guide for which ones to look at more closely and the ones to avoid.

For the astrophotos I'm using the camera direct on a 2000mm fl telescope using a K adapter for my K1000, or piggy-backed onto the telescope (to use its drive) when using prime lenses to get a bigger field of view than the telescope gives. A 135 has a big enough field of view to get quite large groups of stars in.

Mick