At the front of the lens yes. When I described it as a kids telescope with a screw mount I wasn’t exagerating. You basically had a not absurdly wide aluminum tube with a much wider front piece containing most of the elements. F-stop was fixed, but there was a plastic ring with slight adjustments so you could make sure it was actually at 4. Twiddle it till the lens is functional essentially. Focus was likewise fixed at infinity. But you had to slide the forward part of the lens backwards and forwards on the tube to achieve that single focus point. As nothing was actually attached together. Just bits of tubing sliding on each other. So things could wander. The 2000mm was slightly less janky.
We used to hook them up to the display cameras and my old k-1000 to play around. They were the fun kind of terrible. But they were terrible. I think we mostly carried them because they looked impressive in the display case. No brand name or markings, made in Asia. No clue when they were made but the packaging looked pretty old. But every once in a while a press pool photog who didn’t usually work with long lenses would be stuck and in need of a super telephoto. They’d look at the name brand options for a few grand. Then snap up the POS for a few hundred. Usually return it later too. I heard the things were borderline disposable in terms of durability. We actually made more commission off them than the more expensive Canons. And more off the screw mount adaptors than either.
ETA: iirc you could actually use that 1500mm like a marshmallow shooter to launch balls of paper around the shop. The main tube had but a single element in it. With a hole at its center. The sliding bits were held together by rubber o rings. So you shove a ball of paper in the mount. Pull the front of the lens all the way back. Then pop it with the heel of your hand to shoot the paper ball.
We also used to use a screw driver and canned air to turn the capacitors in disposable cameras into primitive flash bangs.
