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pmrid
30-03-2024, 03:53 PM
I've been given a 80mm achromatic objective lens and cell that I would like to put to some use. It's about 900mm FL making it about f12 or so. Probably be OK for a bit of planetary or something like that.

But the tube assembly is going to be a bit problematic.

Does anyone know where I can source a suitable tube? Or have any idea how to DIY a CF job.

Saturnine
30-03-2024, 05:23 PM
Hi Peter
You could try either of these offerings for alum tube of a suitable size.

https://www.ebay.com.au/itm/275880323296?itmmeta=01HT705VENGGAB P43K5W3H7MVR&hash=item403bbfa8e0:g:18wAAOSwlah
https://www.ebay.com.au/itm/181318321070?itmmeta=01HT708PT50G24 VSB4BR3Q40GR&hash=item2a376a03ae:g:yc4AAOSwdR1hJ v-3kd-C-

pmrid
31-03-2024, 12:08 AM
Thanks Jeff. They look about right. I'll grab one and see how it goes.

muletopia
31-03-2024, 12:49 AM
Peter,
Some where o this site is a picture of an ota that my wife knocked up to make a 6 inch newtonian. Essentially half inch wide quarter inch thick wooden strips with semicircular tongue and groove full width of the strip thickness,painted black inside and a sheet of fibre glass epoxied to the outside. Light,strong rigid and negligible thermal expansion.
Chris

pmrid
31-03-2024, 01:49 AM
Thanks Chris. I'll see if I can find it.