Does anyone know of other options to make a camera lens into a telescope? There are only a couple of these not-produced-anymore "Kenko Lens2scope Adapters" available to buy online but maybe there are other still in production items I'm not aware of.

That’s actually pretty cool. I want one.

Plenty of options. They’re called pentafinders, and any camera rental house will have some.

You don't put the camera on the eyepiece, the camera becomes the eyepiece. I've used my DSLR for decades with my scope, until I bought a real astro cam.

Usually it's a combination of a T-ring to adapt the camera lens mounting system into a generic screw form. Then a T adaptor gets screwed into that, which is basically a small little tube with the diameter of the hole the eyepiece goes in.

On some of my scopes the hole is large, with a piece that slots in and allows for small eyepiece to be placed. When I remove all of that I'm left with a large hole to fit in the T adaptor. This is important as it allows the entire sensor to receive light.

There's also an extra piece one could screw on called a coma corrector. This is an extra lens that reduces distortion due to the optics of the scope and of the camera not being exactly compatible. But these reduce light throughput and can cause vignettes, but some people swear by them.

These are all very cheap components (relative to all the other astro photography stuff) and they are easily available.

I 3d printed one once. Kinda fun, but upside down

Thanks for the tip! I'll definitely be looking into that term

I'm assuming you put glass into it. How'd you figure out how to make it work properly?

Thanks but I'm trying to find something that makes it so I don't need to use my camera as the eyepiece. I would like the ability to use my camera for photos and when I just want to look at stuff easily, use an eyepiece adapter without the camera. I have a quality telephoto lens that could be a nice telescope, and I can't afford a telescope currently

A used SLR!

Just look through the viewfinder. Add a padded rubber cup, if you wish.

It activates the lens’s stabilization and autofocus, which is immensely useful and something an adapter could never do. And the plastic crop bodies are cheap, and not that big/heavy.

You can also get right-angle adapters for the eyepiece, like:

I forgot about those right angle viewfinders. Good idea!

It was just something from thingiverse so you could put a 1.25" eyepiece up to a Canon EF lens I think

I'll look into that for sure. Sounds like it could work great