Quote:
Originally Posted by mura_gadi
We have a supplier of marine flexiply here, that will go down to 200mm+ circumferences. 5mm and 8mm thickness, you might go close at 8mm for strength and flex.
The other one is sonotubes, bunnings stock them but I can't think of the Australian name. Concrete form work tubes...
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Hi Steve,
I hadn't thought of flexy ply, but I don't really want to make the tube from scratch as I have a wonderful 900mm long 200mm diameter thickish Aluminium tube (thanks again MattT !!!) that I have the correct Parallax tube rings for- it's more a matter of dealing with and joining on a 300mm section.
I have thought on the sonotubes and I have a short length of something similar that I was considering using to help as a prototype if i went for an afocal type arrangement which would only need to be about 550mm long . It would comprise the 270mm plano convex front element and ~100mm plano concave rear element to make a ~2.7x afocal lens which could be coupled to the front of an existing ~100mm telescope - I should have mentioned it as option 3 in my first post. It could turn my 300mm f/2.8 lens in to an 800mm f/2.8 - It would be great to try to see what's possible
or not.
My first job is to make up an optical bench of sorts to test/confirm exact focal lengths and adjust lens element positions. I have a simple idea for that and will soon share a picture here.
Many thanks
Best
JA