|
Hi Ralph
I hadn't connected that you were making such a long focal length so ignore my comment about going back to 80.
If you are trying to avoid parabolizing I don't think you need to go to F13. I suspect f10 would be ok and easier to mout. If you have a program like Tex or figure xp, just set it up for your mirror and enter the same reading for each zone and see what wavefront error you get.
Rod
|