Russian grease for lens helicoids. It's called CIATIM-201. 25ml for $9.99 shipment included.
And this Rolleiflex copy:
Reflekta II (with Trioplan 75mm view/taking lens).
Broken. Bought to rip off the lenses.
I have a similar one, but it's in too good conditions to be butchered
This Reflekta has the advantage of having the two Trioplans easily accessible removing just four screws of the front plate.
To extract the objectives from the other twin-lens reflex I have, I should dismantle the camera almost completely.
The viewfinder lens is what i was looking for. It has no iris but should be easy to adapt using an M42 helicoid.
The Trioplan that is set in the leaf shutter is VERY difficult to use with a reflex camera. I tried using a compatible Schneider barrel, but I couldn't get infinity. With the shutter it's even worse... Best used with a mirrorless.
I have a few Trioplan lenses in different focals, scavenged from different cameras. All come in leaf shutters, and can be used on a Pentax DSLR only at close range.
The only one that could be easier to use is the 45mm that comes with a Pentona. It has front element focusing, and if I'm not mistaken the shutter assembly is smaller than the others. i doubt it's front mounted (that would be great), but I hope to find a way to recess the lens in the mount/helicoid to allow for infinity focusing.
I still have to disassemble the camera and remove the optic, though. I could be wrong...
LAST MINUTE EDIT:
After I lost countless auctions, I finally acquired one of the few (relatively) affordable lenses I really miss. In the past it always fetched more than my self-imposed price limit.
Now, fingers crossed, it seems I've done it!
I should get very soon a nice Super Takumar with 8 elements.
It has dust, a hint of fungus (reported by the vendor), but it looks in fine conditions, and I paid a very reasonable price, considering the crazy BIN offers I've found on Ebay.
cheers
Paolo