Hi. I recently spotted this Lens while wandering through Newtown (Sydney) and I bought it. $180.
Checking out the lens in the shop it certainly appeared dirty inside & knocked about outside. But I thought it might be a nice project.
I just carefully wiped the front lens when I got home and, voila, it became clean.
This is a shot from where the following was taken. This is at 50mm on a Sigma DC 18-50. Sorry about the quality, I'm having trouble with this lens but it's only to show the distance.
This is with the Tele-tak.
This is a crop.
It's also hand held.
The camera is a KS-1.
I should also add that this is a screw mount lens. Late 60's maybe.