Looking for a 50mm prime Pentax compatible DSLR lens

[Okeydokey]

I am suffering under the burden of choice, there seems so many different makes and models.  I am guessing f1.7 is better than f2 for DSO, the older lens go for less at times and more at others.  Same lenses attracting different prices, what a malarky!

Any brands I should avoid?  Also would f1.2 be better than 1.7 or for that matter f2?

I have amotorised (RA) EQ3-2 mount and don't really want to collect 50mm lenses.

Tight budget, any advice welcome, many thanks!

[Mr Spock]

If you can find one the Chinon 55mm f1.7 is as sharp as a Nikon

The f1.2 or f1.4 lenses of that era are not very good wide open and best avoided.

[Okeydokey]

I do hope this is the kind you are talking about!

http://www.ebay.co.uk/itm/CHINON-55mm-f1-7-m42-screw-manual-prime-lens-/331035074328?_trksid=p2047675.l2557&ssPageName=STRK%3AMEWNX%3AIT&nma=true&si=CmRxV1VCpksDBj1quhIU7Xoej0U%253D&orig_cvip=true&rt=nc

leap of faith