lenses confused

Bit of a dummie question ive got a k5 and am very new at this lark , looking on ebay at old pentax lenses which will fit straight on to my k5 what fitting is it the k fit????:

The following lenses will work with some limitations:
Screw thread with M42 adapter.
SMC Pentax
SMC Pentax-M

All later lenses will work fine. A series lenses are manual focus only and of course remain so. Autofocus lenses are all fully compatible.

Thanks so have i got this right all of them except screw thread which i will need an adaptor and some will only be manual focus,sorry to be a bit thick but like to get some nice old primes but want to get it right cheers

Pentax DA or DFA lenses are for digital (DFA ones also work with film SLRs).
Pentax FA or F lenses are autofocus lenses which will work on digital SLRs.
Pentax A lenses (sometimes described as PKA) are manual focus but otherwise work without limitations. (Look for the 'A' setting on the aperture ring if in doubt.)
Pentax M lenses (sometimes described as PK) as above but you also need to use them in manual exposure mode. (This means pressing the green button to meter every time you take a shot).
Pentax K lenses work the same as M lenses.

A great starting point would be something like a Pentax-A 50mm f1.7

cheers at the moment ive got the 18 55mm kit lens , the 55 300mm da and 100mm macro what would be a nice size portrait lens

Your 100mm macro would double reasonably well as a longish portrait lens, especially if you keep it wide open to f2.8.

Otherwise, if you want something shorter, and cheap, it might be worth trying out an old manual focus prime - I'd recommend the 50mm/1.7 SMCM as a plentiful and decent quality lens that you ought to be able to find easily without spending a fortune.

Here is a full terminology of all Pentax lenses exempt the M42 as this is a screw lens and as such needs an PK adapter. Everything else is explained.
I can not remember where I found this but I copied and pasted this from a website and I go by it all the time. It is very handy to have.
My thanks to the originator of coming up with such a comprehensive explanation.
I hope that will help you as well as it does me.

Pentax Lens Terminology
Lens Series

K: the original K-Mount lenses, full 35 mm frame coverage, made out of metal, extremely solid and well constructed, great mechanical feel. Capable of only manual metering and aperture priority
M: like the K-series, but generally smaller and lighter
AF: like the M series but, but with an AF motor in the lens
A: like the M series, but with an "A" setting on the aperture ring, thus supporting additionally shutter priority and program operation
F: like A series, but supporting modern-age auto-focus (AF motor in the camera body) and digital communication with the camera body
FA: further development of the F-series, more extensive communication with the camera body
FAJ: like FA lenses but without an aperture ring, thus only operable on bodies that can control the aperture electronically
DA: like FAJ, but optimized for digital bodies and covering the image circle of the reduced-size digital sensor
D FA: like FA, but the optics are optimized for both film and digital
DA L: like DA, but featuring a very light construction, thus optimally paired with very compact and light bodies like the K-m

General Terms

* *: the star sign follows the lens series designation (e.g., A*, FA*), and denotes a high-performance lens that uses special-glass elements.
* Limited: Similar to the * designation in that the lenses are of very high quality, but not meaning that the lens is being produced in limited quantities. Star-lenses are generally large and expensive zooms and Limited lenses are generally compact and expensive primes with not very wide apertures.
* AL: a lens that uses one or more aspherical elements (aimed at achieving flat field and corner sharpness with wide-angle lenses).
* ED: a lens that uses extra-low dispersion glass elements (aimed at reducing colour aberrations in telephoto lenses).
* IF: a lens that uses an internal focusing mechanism (lens groups are being moved with respect to each other instead of the entire optical assembly being moved towards or away from the film plane); IF is typically used for longer lenses with large front elements in order to reduce power requirements for the focusing motor and to make such lenses easier to use with polarizing and graduated filters. IF lenses typically change their focal length slightly during focusing. They get wider as they get focused closer.
* Fixed Rear Element Extension (FREE): a lens whose last cell i remains fixed during focusing. FREE lenses achieve low field curvature and low spherical aberrations not only when focused close to infinity but also at very short distances. For normal applications the FREE system leads to small physical extensions, and thus allows the design of physically smaller and lighter lenses. For macro applications FREE lenses exhibit non-proportionately long extensions which aid precise focusing. However, to achieve these positive effects, the FREE design causes the lens focal length to decrease as the focus distance decreases. Pentax has listed FREE as a feature only for prime lenses even though there are zooms that also have a fixed rear elements (e.g., SMC-A 70-210/4, SMC-A 28-135/4).
* Weather-Resistant (WR): a lens that features special seals and is thus resistant to dust and light rain.

Well that explains it cheers

This line could be potentially misleading to the uninitiated. This only applies to one lens, the early AF lens for the ME-F camera. It has nothing to do with modern AF lenses and is a one-off. To call it an AF series is actually just making it up!

I did nor write this one but only use it as a guidance and nothing else. I was aware of the AF issue but I was not sure if I should alter the list or not as I am not the originator.
I decided not to edit this but forgotten when I pasted it in here that some may misread this.
Thanks for pointing this one out!

link you mean like this one

That's the one, although that particular seller - EmiliaArts - often overprices by as much as 50% IMHO. In this particular case it isn't quite so extortionate, but you regularly see these lenses going for £50-60. I see they're also advertising a one year warranty, not sure how that would work...

Hi there and welcome.
I'm a bit perplaxed as to why you've acquired a flagship model K5, and are now seeking 30 year old lenses at bargain basement prices. Seems to me, if you've got the budget for a K5, you should have a 50-135 hanging off the front of it. Regardless, Pentax is a brand where you CAN buy the latest model camera body, whack an M series 200 f4, 135 f3.5, or A-50 f1.7 on, and enjoy fantastic results not available with even the most modern plasticy overpriced variants. Any of those lenses mentioned will produce great results with a bit of care, and are plentiful and relatively cheap on ebay. Good luck with the LBA (Lens Buying Addiction), these manual lenses are the trigger for that incurable addiction.
Regards

i take it then the 50 135 his the dogs danglers then, and has for my budget i aint rich and spent my hard earned cash on a k5 because i wanted to and thats good enough for me, and i think you just explained why im looking at older lenses, not particularly for the cost but just to expand my range and experiment a bit. regards

oh yes the 50-135 is the dogs danglies & my favourite lens by a longway...