What I would say is that a good photographer with the normal lenses will achieve things that others will struggle to match with the * or Limited range.

It does seem to be the main way to get fast glass though - I have an old K series 120mm f2.8 which I think is probably one of the fastest normal telephotos (aside from the 135mm f2.5 of the same era), I'm not aware of anything longer with a similar aperture unless you get into the * or Limited ranges.

I had a Chinon 70-210mm zoom with my P30T, it wasn't a bad performer then but I suspect it'd be seriously embarrassed on digital. I mainly bought it because it was cheap and had an A setting on the aperture ring.

In all honesty I'd say to save your money and buy something better. There are some cracking Pentax manual zooms out there for not much money if you're after an old zoom to play with. Have a look at this or this.

I think there's a definite correlation between online reviews and ebay ending prices. The Pentax-M 40-80mm for example, while a very nice lens gets indifferent reviews on a well-known forum (unfairly to my mind) which I suspect impact the prices. I know I managed to buy an excellent one with original front cap for £20, nobody else bid on it and it's now my favoured macro lens.

Hmm, I think the next working ME F I see is likely to join my collection!

There's a tidy but apparently dead one on ebay for £20 at the moment, I've thought seriously about making them an offer...

That's about £45 - if I saw one that cheap here I'd buy it in an instant! The ME F is a bit more common as I get the impressions that many were sold with plain 50mm lenses attached, but the lens tends to cause bidding frenzies.

Yep, I've always been confused why they did that. It isn't hard to figure out though as the non-standard original auto focus is only found on the ME F and the 35-70mm f2.8 (which look nothing like the SF series bodies and Pentax-F lenses, which were the first to use the KAF mount).

I wouldn't mind an ME F and matching lens, but don't rate my chances of finding both as they usually go for ridiculous money. Might snag an ME F one day though, and the focus confirmation stuff is supposed to work with any lens...

Ahh, hang on - I think the Kf mount you have there is the one-off used on the ME F and the associated zoom. That works like any other pre-A series mount if you attach a different lens to the camera or the special lens to a different camera, the AF will only work with that lens on the ME F.

The Pentax-F lenses were different - they were the first to use the now-standard Pentax autofocus mount with screw drive (basically the A series mount but with the screw drive added).

Stick with what you have and save for some decent primes. Look for the Pentax-M 28mm f3.5 (or the K series version, but that's much rarer), it's a lot better than the standard f2.8 version. Also worth looking for a Pentax-A 50mm f1.7. Even at current prices you should be able to get good examples of both for about £120 the pair.

I have bought all the readily available lenses I want and can afford, now I hunt for the rare and unusual oddballs. Anything K series in other words - I have a 55mm, 120mm and 85-210mm zoom from that range, all of which are great.

I have a Pentax-F 35-70mm zoom which works perfectly on my K-m, so yes, they will. The Power Zoom contacts (where present) were designed so that they wouldn't foul on bodies or lenses that don't have them, if that makes sense.

AFAIK Pentax now use the same contacts to power the SDM motors, hence why they're present in some DSLRs. These can power the zoom function but can't do any of the special tricks that the Z series film bodies were able to do with power zoom.

To the best of my knowledge the slowest Pentax AF 50mm is an f1.7.

The problem you'll run into is that by the time Pentax went auto focus the consumer market wanted zooms rather than primes, so the AF primes aren't as common as the manual ones. The old M 50mm f1.7 for example was sold with thousands of cameras as a kit lens, by the time the F or FA versions appeared the kit lens would have been a zoom. Pentax have never made cheap primes - the zooms are designed to fill that market with the idea being that if you want a prime you'll be serious enough to pay.

Have a look for the Pentax-A 50mm lenses (they offered an f2, f1.7, f1.4 and f1.2), these will work with the auto modes on your K100D but are still manual focus. You'll have to buy second hand but there are plenty of excellent examples out there.

I'd say to use it.

I've been keeping an eye on ebay for an LX too, but all the sub-£200 ones seem to be a bit rough cosmetically and you've no idea how long they'll work for before needing a service (which will not be cheap). Yours is a brand new camera with no need to worry about that for some time to come. Failing that there's an example on ebay currently for £170 which is definitely "well used" - if it was nearer £120 I would be tempted however...

I'd have pulled the protective film off and put a roll of HP5 in by now if it was mine!