Re: [ATM] refractive index of air

[Dominic-Luc Webb <dlwebb@canit.se>]

On Wed, 8 Aug 2007, Richard wrote:

> R> Ah, you're doing it in the correct order
>
> Erm.. or not... I think you'd better ignore me today.
>
> If you still have the option, it's much easier to finish the secondary
> first, and then tweak the design to suit the final secondary before
> finishing the primary if you can. Far more difficult to try to get ROC
> and K of the secondary both to exact design spec.


I reasoned this as well. I have only done a little polishing on
the still spherical F/4.8 primary, and it looks like a decent
sphere. I expect to be able to get the secondary to match this
ROC. From there, the plan is to get the secondary hyperbola
polished as close as possible to original specifications. When I
am confident about the figure of the secondary, I am hoping to
just back calculate the primary conic and tweak the primary
figure as needed. I was not really sure if I would have to go
back to fine grinding to change the primary ROC. This is my
first RC scope. I am not even sure yet how accurately I can do
the Norman test. Somewhere in all of this, I expect I will
need to test the complete system.

At some point, I may need some advice on a field corrector. I
should probably save that until both mirrors are polished, so
I can see how strongly curved the focus will be.

Dominic-Luc Webb

_______________________________________________
ATM mailing list http://www.atmlist.net/