In my former life I was a professional photographer for over 40 years. I hung on to some of my camera equipment that I wanted for my retirement. A screw mount Pentax SLR with a complete set of prime lenses is one of them. In that bag there is a fine Pentax Takumar 300mm f4 screw mount lens. It's SHARP.
I just bought an eye piece from B&H photo that they call a GP PENTAX UNIV LENS TO TELESCOPE ADAPTER. The SKU# is "GBPULTA". It cost me $39.95 plus $4.95 S&H.
I put the lens on my Slick tripod and screwed the tele adapter on and WOW! Right side up correct image with 30X magnification. The lens focuses from 18' to infinity and is sharp across the entire distance. The field of view is huge for a 30mm magnification telescope.
I'll be using this rig for BPCR long range spotting this season.
How's that for recycling?
DD-DLoS