body - Differences between Pentax K, Q, and "Lithium-Ion" SLR bodies?

This may be a total noob question...

My dad had a decent Pentax 35mm SLR (I forget the model but it had AF etc. and was moderately fancy for the time) with a couple of good lenses. I believe I can buy a digital body & re-use the lenses which should get me a decent setup for low outlay.

eBay lists categories of Pentax bodies: K Body, Q Body and "Lithium ion" body, can anyone tell me the differences between these?

Also, which would be a decent pick 2nd hand as a solid basic digital body? I don't need bells & whistles or "more megapixels".

Edit: Just to follow up, I've dug the gear out and the list is as follows:

• SFXn 35mm body


• 1.7x AF Adapter



• Manual 50mm lens


• 28-80 1:3.5-4.5 AF lens


• 70-210 1:4-5.6 AF lens


• Tamron Tele-Macro 100-300 1:5-6.3 AF Lens

I've asked a new question about what I've got and how useful it is.

Answer

Pentax introduced autofocus with their K-mount, so the camera in question is most likely to use that mount. Before that, they used a screw-mount, so you should easily be able to tell which you have.

Pentax has the reputation of one of the best compatibility with legacy lenses. Pretty much any Pentax (or third-party) K-mount lens built since 1970 can be used on a Pentax DSLR. All of them have model numbers starting with K: K-1, K-5 IIs, K-70, K-200, K-P, etc. Generally speaking, fewer digits are used with higher-end offerings, which means more direct controls.

The obvious choice for legacy Pentax lenses is a K-1 which is the flagship DSLR and the only full-frame one in the line-up. It is expensive but will use legacy lenses with the same field-of-view as on a film body.

All other Pentax DSLRs are APS-C which means that the field-of-view of lenses gets reduced by 1.5X, so everything will appear more zoomed-in. The K-5 IIs is spectacular in this category but a K-5 II and K-5 is almost as good. The K-7 is one generation older but still very good.

There are Q-mount cameras which use a completely different mount. This is not popular and there is often a rumor circulating that it has been silently discontinued. It has a huge crop factor, 4.6X to 5.6X, depending on the model, so adapted lenses significantly longer. Image quality is also rather low as it is akin to an ultra-compact.

Lithium-Ion is a type of battery, nothing to do with the body. Nearly all digital cameras on the market (if not all current ones) use this type of battery but older models, until the K200D also supported standard AA batteries which could be Lithium, Alcalin or, more commonly for rechargeables, NiMh. The last two models that supported AAs also supported Lithium-Ion batteries which have less capacity but are at least rechargeable when compared to plain Lithium AAs.