6 Sep
2011
6 Sep
'11
8:58 a.m.
On 9/6/11, Chuck Hards <chuck.hards@gmail.com> wrote:
On 9/6/11, Chuck Hards <chuck.hards@gmail.com> wrote:
On 9/6/11, Chuck Hards <chuck.hards@gmail.com> wrote:
If you want to make a small, dedicated white-light solar scope, you can install the filter material JUST behind the objective.
OK, before someone else posts it, it works for Gregorians too.
Around and ahead of the optical surface of the secondary, but inside the tube itself.