Re: [APML] Suggested Astrophoto Accessories for Vixen VC200L

["William R. Mattil" <wrmattil@ix.netcom.com>]

Allan & Julie Whetzel wrote:
> 
> Hello,
> 
> My VC200L is on its way from Orion and I wanted to get a quick rundown
> on the accessories I should get for connecting my OM1 for prime focus
> work. John Mirtle and others have suggested getting a 2" eyepiece
> adapter so I can use 2" accessories. I plan on ordering one in the next
> couple days.

Good Plan !

> Is a Lumicon 2" Newtonian Easy Guider the appropriate OAG
> to use with an ST-4 for autoguiding ( I think the appropriate T-ring
> will come with the NEG)? Will I need to get any extension tubes from
> Lumicon to allow the ST-4 to reach focus?

It is indeed. And yes the appropriate T-Ring does come with the OAG.
These are not standard T-Rings but are modified so that the couple
directly to the OAG via a locking system. But a regular, garden variety
T-Ring will not work with the Lumicon OAG. And unless the laws of
physics have changed because of the Vixen 200L you will not need any
extension tubes for the ST-4. The nosepiece will be about .25 inch to .5
inch short of being fully inserted into the OAG after the camera has
been focused.

> Also - just so I understand,
> can someone briefly go over the benefit of 2" accessories compared to 1
> 1/4".

As a Noob when it comes to Cassegrains (or anything else) <laughs> I
think that the biggest single advantage is that due to the camera
hanging off the back of the OTA by a fair amount, there is a bit of
moment arm that this weight can use to create problems for you. The 2"
Attachments would seem to be more secure to me. But hey, its my opinion
and its free. My Cassegrain has only a 1.25 inch focuser and due to this
excessive length (yes the rear spacing is within spec .. speaking of
which can anyone comment on the Vixen here ? Is the primary moveable to
adjust the rear spacing ?) there seems to be a tendancy for this to want
to sag a bit. So I have to be extra careful in tightening things down.


>  Additionally, are there any good filters I could get from
> Lumicon for nebulae photo's etc?

The Lumicon Deep Sky Filter works with film but as I am certain that
some will point out it tends to provide a magenta cast on long
exposures. Particularly noticeable on non nebula images. I have a nice
image of a magenta M51 in my collection. 1 Hour on E200 with a Deep Sky
Filter ... Looks awful. But on shorter, nebula targets the Deep Sky
Filter can help if there is some light pollution. But a nice dark sky is
preferred.

> Anything else I should put on my
> shopping list?

Fast Film suitable for f/8, f/9 ????


Here's a link to mine:

http://www.celestial-images.com/equipment/Classical_Cassegrain.gif

And a first light image:

http://www.celestial-images.com/equipment/Cass-1st-light.gif

nothing spectacular mind you, just wanted to see what guiding at 3795mm
of focal length was like :^)

Regards


Bill

-- 
William R. Mattil	|                              
wrmattil@ix.netcom.com	| http://celestial-images.com      
(972) 399-4106		|
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