I'll take some photos of it.
It is two tubes about 3.5inches long, one inside the other, with a T2 fitting on the camera end and a female thread of about 34mm at the other, which is useless. I tried some step ups but it's between 34 and 35mm and none would fit so I couldn't get a lens onto it. I bought a solid looking M42 lens cap off Ebay, screwed it onto a 10mm extension tube and fixed this onto my lathe. I then cut into the flat end of the lens cap to leave an M42 threaded tube and then cut into the inside wall of that tube (the ex lens cap) a fraction at a time until the end of the trombone tube thing would just fit inside it. I secured it with Araldite and left it overnight. Now I have a robust M42 fitting on the end of my tubes. The outer tube has a locking ring so when you've used it - like a trombone slide - to focus, a quick twist secures it. The addition of a focusing helicoid between the tube and the lens could even tweek things further (I leave the lens itself set at infinity).

The preset 105mm is a super lens (and commands a good price). The Soligor version, also preset, just pips it in my view. Perhaps it's the copy I have? Both are superb and well worth grabbing if you see them. Peter makes this quite plain with these super shots.

Your comment sums that up quite well. I have trouble deciding over those two too (!) I think the B&W wins by a whisker.

Very difficult one to photograph. Well done.

I can only speak about the *istDS which does the same thing. The terminals on the inside of the battery door get compressed every time you close it. They lie nearer and nearer to the door over time and need to be physically pulled out again to make a decent contact. At the same time, a thin and invisible layer of insulating gunk accumulates on their surfaces. Give them a good hard clean with a lens cloth. It drove me crazy and I spent pounds on various batteries. It played up with a set of Eneloops last time I took it out. Cleaning the terminals fixed it at once.

As you say, quite a testament to its abilities.

I think the shallow DoF is due to the sheer length of the tubes being used. It's one long tube that slides out from a similarly long tube, doubling its length. I was using the sliding bit to focus it. I think they were originally intended to go on a celestial telescope.

Silly question ........ I presume when you are using the green button the mode is set to 'manual'? Also, a lot of M42 lenses don't need the green button. If the switch on the lens is set to 'manual' they will work with the camera in AV mode. If you have just taken a picture in live view and you press 'play' the mirror will indeed thump around because live view is cancelled before an image can be displayed and as soon as you half press the shutter button to cancel the image display the mirror will again thump up to resume live view from where it left off. Best to cancel live view deliberately before viewing an image and only re-engage it when you next want to use it or it could end up driving you potty.

Welcome to a great forum. Please do post your pictures !

And the K3ii has exchanged it for GPS