Please see my post just before yours; question answered!

Wouldn't you be better seeking out a set of tubes with the electrical contacts so you can use auto focus, set the aperture and stop down the lens? Search for 'Pentax K AF extension tubes' (if that's what you want rather than the M42 screw ones.) However most of those on ebay don't look to have the electrical contacts.

Something like this might be worth considering:
http://www.ebay.co.uk/itm/Tele-Plus-Extension-Tubes-For-Pentax-P-AF-Mount-7396-/...

Proof they exist! However they do seem scarce! I have a set of Jessops branded ones (sorry not for sale!) I could however help with a cased set of original Pentax K manual tubes in excellent condition, but still reckon you're better off with AF ones.

Is it for use on film, APS-C or a K-1 ?
Have you looked at the reviews on PentaxForums.com ?

I haven't! Favouritism.

It's somewhere I must go too sometime. Did you pay the £5 parking fee, sounds a lot (though not as much as your visit to the War Weekend incurred - I hope.) I gather there is a free car park too nearby.
The weather today surely didn't help with the photos though that perilous tree photo always works.

There's an independent test of Windows Antivirus packages here:
https://www.av-test.org/en/antivirus/home-windows/
For general home use it seems the free versions from Avast, AVG and Avira are rated nearly as highly as Kaspersky and BitDefender with regards to virus detection. The Microsoft one doesn't fare so well!
It's still necessary to block/check for malware and spyware for which the excellent Malwarebytes program proves useful.

Last night I discovered a site that does 'online' photo effects: http://www168.lunapic.com/editor/

Some may find it useful for something such as this:




The original image was this:

Did you mean: for Tokens read Tokina, and for Samsung read Samyang? Predictive text issues I guess?!

I've 40 year old SLRs and lenses and none has had a problem with dust, though a cricket did jump into one of the camera bodies once while changing lenses! Just a little too macro.
Re switching camera off while changing lenses, if it happens to be an evf type like the K-01 and Q (and for those that have them micro 4/3 etc.) the sensor will be exposed (shutter open) and far more liable to any dust issues and electrostatic so for these DO turn the camera off first. I'd recommend it too with any camera to be on the safe side, but if you forget don't worry. Just make sure any crickets are extricated from the camera body before putting the new lens on!

Really? I don't think so. I can't believe someone would spend so much on a camera and not insure it.