[David Fitz-Henr]

Originally Posted by marc4darkskies

Congrats David - I know how long and hard you've worked on this project. You should be pleased with such a good preliminary result.

Thanks Marcus, yes I'm ecstatic having such a good result on my first test images! I'm also very pleased with the way some of my design features have worked out; for instance, collimating the secondary mirror is an absolute breeze! No wrestling with a central nut for rotation, etc.

Originally Posted by marc4darkskies

Don't like your name for it though. Why not just call it something simple and unassuming - like the The Great Fitzy Newtonian.

Hmmm, yes well I guess I just don't have your turn of phrase, Marcus! Though it could have been worse, what if it had been the Great Fizzer

Originally Posted by gregbradley

Super result. You must be very happy with that.
Greg.

Yep, thanks Greg - very happy indeed. It has taken a few years so it is a very exciting time for me at the moment!

Originally Posted by Satchmo

Congratulation David on a really superb piece of engineering.

Regarding diffraction spikes I have heard anecdotally that another way to suppress them is to insulate the vanes with royal black velvet. The thermal boundary layer you get on the surface of bare metal vanes actually creates an optical thickness much thicker than their mechanical dimension. The insulation while thickening the mechanical profile reduces the optical profile by removing the thermal boundary layer.

Another approach is to use a curved spider milled out of solid aluminium.

Thanks Mark! Yes, I actually have some black flocking material from Protostar that I will use in key places. I have thought of using it for the vanes but I feel it will add too much to the thickness. Interesting though what you suggest about the thermal layer, but this won't be a concern as I will have three maglev fans mounted beneath the main mirror which will pump sufficient air up the tube to prevent any thermal layers forming.