After doing some initial trials on my C11, I realised that I would not improve dispersion or even resolution over my old C8.
Then I hit on a cost effective idea to push the SA up the baffle tube of the C11. ATM Andrews are selling GSO 25mm extension tubes for $9. For $45 I can push the SA 125mm further inside the C11 than before which should allow me more dispersion without running out of focus travel.
The GSO 0.5 focal reducer is another experiment to combine with it to reduce the star image size and improve resolution (provided the optics are up to it
).
I had an adapter turned up at the local machine shop, with a 1 1/8" x 42TPI thread for the extension tubes and a 48 x 0.6mm thread for the 1.25 to 2" adapter, but these extension tubes will work straight through a 1.25" EP holder provided the bore of the EP holder is clear
. BTW if you are thinking of doing this, check the filter thread on the 1.25 to 2" adapter... my research says it should be 48mm x 0.75mm pitch, but mine was 48 x 0.6! ...and take the adapters to the machine shop so they can make sure they fit.
I doubt I'll get a chance to give this it's first light before next year
... but I'm looking forward to seeing what I can achieve with this. I'd like to get close to 20A resolution at 4" seeing
.
This should also be suitable for refractors, but would result in an obstruction in a newt.
Al.