Re: [APML] Coma corrector needed ?

[Herm <hermperez@worldnet.att.net>]

I agree with Tom, but I don't think the Lumicon CC will give you 100%
illumination anywhere in its field with an f4 system.. the lens is too small and
too far away from the film.. its an expensive system but it works well. The best
performing and cheapest way is to use the Vixen 60mm coma corrector intended for
the R200SS 8" f4 newt.. usually about $99 from Orion, the catch is that you need
a 60mm focuser.. luckily Orion sells a copy for $29 (this is the focuser that
its used in their X series dobs, a copy of the Vixen focuser). This focuser/CC
combo with the Vixen wide direct photo adapter will give you 100% illumination
to the edge of the negative.

The only problem is that Orion stopped selling Vixen stuff, so the CC and direct
photo adapter may be special order... let me know if you intend to go this route
and I will give you all the details on the items needed.

BTW, so far I have tried all three different systems.. Lumicon, Baader
Planetarium, Vixen and TV.

"Tom & Lou Krajci" <krajcit@3lefties.com>  wrote:

>From: "Mike & Dianna" <galaxy@ncweb.com>
>
>> I have a home built 8" F3.5 newt for AP only . When I researched coma
>> correctors, Lumicons and the TeleVue parracor, I found that the Lumicon
>has
>> a larger area of glass than the Televue....therefore less vingetting.
>
>I disagree.  The spacing for the Lumicon corrector is farther from the film
>plane than for the Televue corrector.  For an f/4 type of light cone...they
>both should give roughly the same 100% illuminated field...about 1 inch in
>diameter.  Because the Lumicon corrector is a bit farther (3 and a little
>inches versus 2 and a little inches for TeleVue)...the rate of illumination
>fall off for the Lumicon may be a bit less severe outside the one inch
>diameter circle...but it's probably not a big difference.
>


Herm
Astropics http://home.att.net/~hermperez

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