Gonna go out on a limb here and take a guess this is the DA* 50-135mm, correct me if I'm wrong though.

Hrm, am I the only one who says maybe wait? If you want the video / additional features on the K7, then wait. If you don't - then buy

Oh yeah, your DOF is razor thin, and if you *using a fast aperture it's even thinner! This is with a f:2.8 on my old lens - see how the curvature of the bulb changes the focus? That means you don't need fast glass to be a macro. Below is a 100% crop on one of the letters taken just now.

[IMG]http://img693.imageshack.us/img693/9854/cropl.jpg[/IMG]

Well - depends on your budget I suppose. You can pickup a old manual lens for 20GBP off of ebay and get some good mileage out of it. Hell, the macro tubes almost cost that much when shipping was included! Anyways, that's how I started with Prime lenses, through an old manual Auto Chinon - an example of the closest without a macro tube, and then with a macro tube are below:

[IMG]http://img85.imageshack.us/img85/674/nonmacro.jpg[/IMG]
[IMG]http://img514.imageshack.us/img514/2388/tubes.jpg[/IMG]

BTW: Those are the full images, just downsized.

Depends on the lens. I'd personally use lenses that allow manual control of the aperture. I just put the tube on the lens, mount it on the camera, and use it in either AV and make liberal use of the green button, or M and use live preview to figure out if I got the right curves on the histogram.

If your lens doesn't have full manual control, I think it's left wide open when mounted. I wouldn't imagine this would hurt anything. Also, just note that your lenses will be in MF mode while you do this.

I've got an old Auto Chinon 50mm f1.7 full manual lens (even though it says auto in the title) - and it's actually pretty decent. It holds up pretty well against most M-lenses of the day (the MTTF chart I found shows it's very similar to the Pentax M-50mm f1.7)

Hrm, true, that'd be one slow arse zoom at that point. Maybe if there was enough light (I'm thinking about super bright day in the desert / ski top type of light), it'd be bright enough, but I'd also bet that the throw on it would only allow for minor corrections in focus.

$38,000 for this bottle of single malt: http://www.forbes.com/2006/06/13/expensive-whiskies-world_cx_np_0614feat.html

While I did know that it turns older MF lenses into AF ones, I had thought that the range was limited. I just had the brilliant thought that it would make my Tamron 500mm mirror an AF lens, and was wondering if anyone had experience with that.

EDIT: Anyone know if any cheaper TC's add this AF to older lenses?

Well here is a link with one that has both the AF drive shaft and electrical contacts (little bumps) http://ecx.images-amazon.com/images/I/41Xf5RR8JCL._SL500_AA280_.jpg