[Digitalis]

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how much are apature ones? where they arent manual

not that much more expensive I suspect. Extension tubes are pretty simple things.

[shadmanaj]

you can try looking at Thomas Shahan's work on flickr. He uses some old k-mount lenses with extension tubes. Guy's a genius.
Flickr: Thomas Shahan's Photostream

[JeffJS]

The last set I saw, that were capable of A type operation (you'll still be manual focusing) was about $120. Made (or marketed) by Vivitar. No one makes them for Pentax anymore as far as I know. What you could do is get a couple cheapo 2x Tele-converters and remove the glass. Just about any with the contacts will work. Stack a couple of those up and you'll be back to full auto exposure.

For the matter of manual ones, like the ones you linked to, the bellows you say you bought will do the exact same thing AND give you some variability. It is just not as easy in a carry around package.

[mantis]

ah dam, thought you could get auto focusing ones, and more so, thought you could get them for pentax, unless i get a second hand one.

yea maybe ill just stick with my bellow, i havnt received it so i dont know what its like exactly, wether its flimsy, hard to use, etc etc

[yeatzee]

and how much are apature ones? where they arent manual

~$180 iirc on ebay

Not worth it by ANY means IMO.

I can't think of one reason to spend 9+ times the normal price of extension tubes for those...

edit: http://cgi.ebay.com/Anillos-extensores-DELTA-macro-13-21-31-para-PENTAX-/350...item518bb5fd4a

[JeffJS]

Somehow, I don't think you're quite getting how this all works.

Take one of your lenses, not on the camera, any of them (k mount) and set it to f22 with the aperture ring. If no ring exists, it's already there at f22 (or whatever the largest number is). On the rear of the lens is a lever, spring loaded, that will open and close the aperture blades. Moving the lever, you should see the aperture blades moving (take both caps off of the lens). You should be able to open the aperture, release the lever, and the blades will snap back to the smallest opening. This is true of ALL K mount lenses.

Your camera does exactly the same thing. When you put the lens on your camera, it holds the shutter blades all the way open for focusing. When you take the photo, the blades are allowed to snap down to the predetermined aperture. At the very least, you want your extension tubes to have the connection levers for that to take place. Otherwise, (and this isn't necessarily a bad thing) you have to use your lens in manual mode (there has to be an aperture ring and take the lens off of A), and stop the lens down to your desired aperture yourself. This will also be true with your Bellows, Unless, it is a type that with a cable you can actuate that lever. The Pentax Bellows A can do this but it requires that extra step at exposure time (and still requires an aperture ring).

The 'A' type lenses, are Manual focus lenses that allow Auto Aperture control. They have a contact on the mount that will communicate with the camera at exposure time where to set the aperture. A, FA, DFA, DA, F, type lenses all have this ability. M, K, and M42 (screw mount) lenses do not. The premium types of extension tubes will have the Contacts on them to allow that A type operation. There is not now, nor (to my knowledge) has there ever been a set of extension tubes that allows Auto Focus. There are Tele-converters that do, but not extension tubes.

[mantis]

haha cool, ok thanks mate, i was under the impression the extension tubes were able to do so.