From: "Dwight K. Elvey" 
To: atm{at}shore.net
Reply-To: "Dwight K. Elvey" 


Hi
 Here is an alternative. Build the corrector similar to
what would be used on a SCT. Instead of the normal secondary mirror, use a
Barlow with a similar focal length as the SCT's secondary. Place a flat
secondary mirror in front of the corrector/Barlow, similar to what a Newton
would have.
 If my thinking is correct, it would be easier to baffle because
you could make a tube that would go up from the Barlow to the secondary.
This baffle could also support the secondary so that you'd have no spider
vanes.
 Anyway, it is just a thought on how to avoid using a hole
in the primary and still have a nice short telescope.
 Of course, if the mirror is parabolic, you just need some
nice flat glass.
Dwight


>From: "Frank Q" 
>
>Hi All
>
>My personal preferences:  1) NOT pierce the primary. If the surface has a
>good figure, piercing it
>might ruin it.  2) You run the risk of scratches.
>
>I like Greg's options, especially the Lurie-H **IF** you have a spherical
>mirror. You can make the
>correctors out of plate glass (as someone else on the list has done). Here
>the advantage is that
>the glass is relatively cheap and you'll have a good instrument for very
>little cost.
>
>My 2 bob's worth
>Frank Q
>
>>
>> With that fast of a mirror I would say off-hand, Schmidt-Newt, Mak-Newt or
>some other type of corrector-Newt (Lurie-Houghton, Ross).
>>
>> Are you willing to pierce the primary?  How about a Cass Variant?
>SCT,Mak-Cass, RC.
>>
>
>
>
>

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