It depends on what you want it for.

If you want a standard lens for your K7 then the 35mm is a clear winner. I find 40mm just a bit too long on digital. That said, unless you actually need the Macro function then at least try the new DA 35mm f2.4, it's an absolute bargain considering the image quality.

40mm/43mm is great on film, but I can't fathom why Pentax made the DA 40mm but nothing around the 28mm mark. Something like a 28mm f1.8 would have an equivalent field of view to the 43mm on film (Pentax made this as they reckoned it was the true standard lens, as opposed to the 50mm which 99% of cameras were sold with before zooms took over) with the same potential for shallow depth of field effects. I know I was very happy with the old K 28/3.5 on digital and only added the DA 35mm f2.4 to the collection as it's easier to work with (all exposure modes and AF, rather than stop down metering, no aperture data in EXIF, and manual focus).

I think I know the answer to this but want to check I've interpreted the manual correctly. If I put my Super A in Av mode (camera set to auto with lens set to a numeric aperture, rather than "A") as I would with K or M lenses, will TTL flash still work?

I took the manual's wording as meaning that the camera and flash will automatically decide what level of light output is required based on the aperture selected and film speed, but is this correct?

The recoil would presumably be the biggest problem. Your secret agent assassin will struggle to blend into the crowd while slipping away with a broken nose!

I have the AT-X 28-85mm. It's a PK mount, came with a nice black ME Super I wanted but it isn't a bad lens at all. Fairly light, smooth controls, my only complaint is that the focus ring is backwards compared to standard Pentax gear, it's also a bit bulky. I found it reasonably sharp on test, AFAIK AT-X was Tokina's premium range at the time?

If you can get it cheaply then give it a go, my view is probably coloured by the fact that I paid the going rate for a tidy black ME S and the lens was a bonus. You don't tend to value (effectively) free stuff quite as highly as things you've paid for.

The button on the camera body doesn't lock M42 lenses in place as they usually aren't wide enough to cover it (some are, and can have a hole carefully drilled to convert them to K mount if you fix the adapter to the lens and remove the little tab which would lock it in place).

The standard M42 stop down mechanism is a pin protruding next to the rear element of the lens. Press this in and the lens stops down to the chosen aperture (M42 bodies have a little paddle to do this). This can be a problem if the lens doesn't have an Auto/Manual switch as the lens won't stop down (K bodies lacking the paddle to depress it). Some people use a thin sliver of plastic superglued over the pin to wedge it down permanently. If there's a switch then just flick it to Manual and all will be well.

As for the SR, it should ask this as soon as you turn the camera on. Are you sure SR is switched on and the camera is properly set up for manual lenses (aperture ring set to "permitted" or whatever the exact wording is)?

Providing it's in good condition then you got a bargain alright. When they do turn up on ebay they tend to be priced higher.

Talking of which, keep an eye on there for the lens hood, they do appear from time to time. If you visit the Dimitrov K mount site you should be able to find the part number for the hood, which will help with the search (try Google as well - there may well be a dealer with a few spares hanging around).

A use for all those broken M series bodies and scratched lenses?

This would be why I keep a battered old ME and 50/1.7 handy in the car when on 4x4 events. If I have to stand in a giant mud hole and photograph a winch recovery I don't really want to take something which cost more than £20 all-in!

Yep, that's what made me think of it. Given Pentax already offer compacts with interchangeable panels it would be very simple to tool such a panel with Lego studs built in.

Lego stores already sell pick and mix cups of parts, combine that with the panel idea and some very interesting customised cameras would turn up!

The Samyang 85mm is worth looking at too. You won't find anything else as good for the same money and in most tests it isn't far behind lenses costing four times as much. It's PK-A fit so manual focus but the camera will be able to read and set the aperture when the lens is set to "A".