Best lenses for an old manual Pentax KM camera?

I was given an old Pentax camera with a Pentax M 50mm f/2 lens on it. What other lenses would you recommend for this camera? Third party lenses are OK as well as Pentax lenses. Thanks

Some very good advice from Pauly on the 135mm telephoto as it's a very sharp lens. I also like the idea of a 28mm wide angle and possibly a zoom.

The Vivitar Series 1 zooms (especially those made for them by Tokina) were very good lenses. Great results across most of the usable zoom range and a very sturdy well built lens (a bit on the heavy side).

Pentax makes a very nice 28-90mm zoom that was designed for their autofocus line but will work quite nicely on your KM.

A great resource for lenses and specifications:

http://www.bdimitrov.de/kmp/

This is a fantastic resource for all Pentax owners and will give you a full account of all Pentax offerings. Keep shooting.

It all depends what you want from your lens: Wide angle? Telephoto? Zoom? There's lots of choices on eBay.

I have purchased some great lenses on ebay for my pentax cameras. You can find other prime lenses by Takumar, which is a division of Pentax, on ebay pretty easily. I have a 135mm prime lens which is good for moderate telephoto shots. A great all around lens is the one you have already, 50mm. You may want to look at getting a 50mm f/1.8 since this would be a "faster" lens for low light shooting.

There are literally hundreds of Pentax manual lenses on ebay weekly for sale. Take your pick. I also have a Takumar 80-200mm lens, which is a great lens for taking wildlife photos with.

In my opinion, the standard 3 lenses you want to own would be a 28 mm for wide angle shots, the 50 mm for standard and a 135 mm for short telephoto/portrait combination. as one other person suggested, and 80-200 zoom will cover the portrait to telephoto range. 85 mm is the recommended lens for portraits. anything beyond the 200 you probably would need a tripod to eliminated camera shake. pentax lenses are reasonably priced used on e-bay, vivitar lenses are generally cheaper but still are of decent quality. if you can find a vivitar series 1 lens for the k mount, these are great lenses.