Evening all...

I do a lot of macro work in the studio. My go-to set up is an APS-C DSLR (D7500) on a Nikon bellows and a variety of enlarger lenses or reversed primes. It can turn into a pretty heavy, weight-forward system, but the bellows is easily mounted on a heavy tripod, so no problem.

Today I saw some impressive stacked images that had been captured with an APS-C Nikon using an AF-S 70-300mm f/4.5-5.6G and a reversed 50mm prime in front of the zoom lens. I happen to have these lenses laying around and thought I would give this lens combination a try. However, when I get both lenses mounted on the camera, their combined weight is too much for me to rely on a camera mount for the tripod. For stability I need to mount the whole system at the camera end of the zoom ring on the 70-300.

The pictures show the setup - the pencil shows about where I would place the collar (80mm OD).

I have looked everywhere that I can think of for a compatible tripod collar, which seems like the best option. But as far as I can tell, there is no such thing. Has anyone else run into this? The OD of the 70-300 is 80mm, but I can't even find a universal collar for that OD. I can build something that will work, but I'd much rather just get a collar with an arca-type baseplate, and be done with it.

Any ideas? Anyone ever heard of a universal tripod collar?

Thanks for any fresh ideas. Allan