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Old 17-04-2008, 10:42 AM
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OAG with a newt and a MPCC, can it be done?

Hi everyone,
Just curious and seeing if anyone uses a OAG on there newt with a coma corrector? and if so how happy are they with the results and ease of use?
Just thinking of the other alternative to using a guidescope..
I know Scott (Tornado33) uses this setup but I think he has a custom made job on his newt.
Only unit I can find is the Lumicon OAG but you need to use there coma corrector with there unit..
Thinking this could be a good setup using a old DSI as a guide camera.
cheers and thanks in advance for any info..
cheers Gary
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Old 18-04-2008, 01:40 AM
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The way i see it, the correctors are made for a specific spacing and light pattern to give a specific imaging circle. If your using the guider chip, it is most likely located outside the image circle, unless it has a huge image circle. So this may add to your distorion, rather than fix it.

Theo
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Old 18-04-2008, 02:14 AM
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Lumicon no longer make their coma corrector.

Which is a shame, it was a good unit.

You might be able to use a Baader MFCC attached to your SLR and a Lumicon Newtonian EsyGuider together. Not sure , can't see why not.

Or maybe a Paracorr Universial (that's the photographic version) and a Lumicon EsyGuider together , again , not sure on that .

Have you asked Lumicon about this directly ?
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Old 18-04-2008, 05:34 AM
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While not having the answer you want, I would echo Gama's concern. The MPCC is designed with an approximate rear to chip distance of about 56mm. The DSLR will soak up about 44mm, so the remaining has to include a T ring, AND your OAG. Is the unit you are looking at anywhere near this slim?
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Old 18-04-2008, 07:43 AM
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Thanks guys,
Well thats the problem. The MPCC is made to go at its spacing which is basically attach a T-adapter for your camera and thats it. The OAG has no option but go infront of the coma corrector. It would have to be thin and with the MPCC made to fit into the 2" drawtube , I can`t see how to do this without making up a custom part.
Then you will need all this extra back focus which will introduce vignetting etc...
I would have thought someone would make something commercially that would be suitiable?
Pitty you can`t get the lumicon one anymore for there OAG...a bit dumb I reckon..
cheers and I shall keep trawling the net for some more info.
Gary
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Old 18-04-2008, 08:27 AM
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Doh, never thought about fitting it in front of the MPCC. I have an old ugly Celestron OAG if you want to try it. I reckon you will need to adapt whatever you are using in some way.
There is a Taurus available I believe, it may do what you are after. Try a Google.
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Old 20-04-2008, 02:40 PM
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Quote:
Originally Posted by gbeal View Post
Doh, never thought about fitting it in front of the MPCC. I have an old ugly Celestron OAG if you want to try it. I reckon you will need to adapt whatever you are using in some way.
There is a Taurus available I believe, it may do what you are after. Try a Google.
What are inside (ID) diameters for the back and front of a Celestron OAGs ?
They are designed for SCTs so they are not exactly low profile. How much back focus do they require ?

Will a MPCC fit inside (from both ends) ?
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Old 20-04-2008, 03:05 PM
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Funnily enough I was spying out the Hutech OAG this morning.
Don't know if it suits your requirements but I wanted to use it with my refractor.
They might not be suitable for APC size DSLRs though.

http://www.sciencecenter.net/hutech/mitsub/oag.htm
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Old 20-04-2008, 06:14 PM
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Quote:
Originally Posted by RB View Post
Funnily enough I was spying out the Hutech OAG this morning.
Don't know if it suits your requirements but I wanted to use it with my refractor.
They might not be suitable for APC size DSLRs though.

http://www.sciencecenter.net/hutech/mitsub/oag.htm
Thanks , the coma corrector and the pickoff mirror will get in each other's way with the Huteck OAG.
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Old 20-04-2008, 07:40 PM
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Quote:
Originally Posted by Ian Robinson View Post
Thanks , the coma corrector and the pickoff mirror will get in each other's way with the Huteck OAG.
hmmm that's a shame.
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Old 21-04-2008, 09:03 AM
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Quote:
Originally Posted by Ian Robinson View Post
What are inside (ID) diameters for the back and front of a Celestron OAGs ?
They are designed for SCTs so they are not exactly low profile. How much back focus do they require ?

Will a MPCC fit inside (from both ends) ?
In all honesty, I don't think it will work, well not without a lot of mucking about.
The Celestron OAG I have is old, and basic, very basic.
It has an SCT threaded ring on the front end, this designed to attach directly to the rear cell of the SCT, so a 50mm thread. On the other end is the standard male T thread, 42mm.
Work it out for yourself, whether it will work or not, but to fit the MPCC to the front will require an adaptor to accept a male T thread, and have a male SCT thread on the rear. Fitting the MPCC on the rear side gives back space issues as this back space is already used up in the DSLR body.
Sorry, looks like a dead duck.
Gary
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Old 21-04-2008, 02:01 PM
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I asked them directly , here is the emailed response Mr Seibert sent me this afternoon .

my question was will my proposed arrangement ie MFCC --> ZMCFA --> EsyGuider --> camera + guider work ?


Quote:
Hi Ian,

The 2" 0 Mag Adapter screws into any 2" standard threaded tube and the
dobsonian model comes with it's own extension tube that screws directly into
any standard 48mm female threads. Anything with male standard threads can
thread into the bacl of the 0 mag focus adapter. So if your equipment comes
with male and female thread capabilities you should be able to use this. If
you need another means of attaching simple let me know what your attachments are and we can work that out.

This should have no impact on the performance of your coma corrector.

Whether or not this setup will work for you has to do with your intravel
requirement when using the cc and your camera setup.

If you put the cc first than followed by the SO adapter then the camera you should get roughly 1 inch of extra focus.
It would be best to put your cc closest to the camera with the SO adapter closest to the telescope. This would give you your best focusing solution.

If you have any further questions or wish to place an order please do not
hesitate to contact us either via email or phone at the number below. You
may also place a secure order via our website. Have a great night.

Harry Siebert
Looks like it will work. Still not sure about the OAG though (he didn't address that aspect). I've replied and asked him more specifically about the OAG aspect.

I have asked simlar questions of Baader in Germany too.

Will keep you posted.

Last edited by Ian Robinson; 21-04-2008 at 03:15 PM.
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Old 21-04-2008, 10:48 PM
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I use an OAG that includes a purpose built focuser
http://www.aeroquest-machining.com/page9.html
Its large pick off prism is outside the actual focuser. I do wish there was a coma corrector in the form of a small segment of one to go over just the pick off prism to correct the comatic stars I get.
I use the MPCC to get rid of coma in the images, but the pick off prism is separate.
Scott
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Old 22-04-2008, 11:07 PM
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Baader Planetarium's response :
Quote:
Dear Mr. Robinson,

thank you for your email.

Sorry - we have no experience with the Lumicon guider.

Please do not hesitate to contact us for any question or further information.

Best regards,

Angelika Hauser

BAADER PLANETARIUM GMBH * Zur Sternwarte * 82291 Mammendorf
Tel. 0049/8145/8802 Fax: 0049/8145/8805 * e-mail: kontakt@baader-planetarium.de
Guess the solution is find someone who will turnout one which has sufficient clearance for the MFCC inserted and a pickoff (just before the front of the MFCC that sends the guidestar light down a light tube to the guider. Don't think it would be low profile unless the light for the guide star can be picked off by a fibre optic arrangement of some kind attached right next to the secondary (say).
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Old 23-04-2008, 03:14 PM
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Further from Mr Seibert
Quote:
Hi,

This is what you can get from SO. My adapter goes directly into a 2" or
1.25" focuser so that you can lock it in place with a thumbscrew. Then you
can attach whatever you want to my adapter. This is the choices you have.
My adapter can come with male t-threads or a 2" or 1.25" female receiving
eyepiece hole so that you can put a male 1.25" or 2" accessory into it. Or
it can come with standard 1.25" or 2" male or female threads. That is the
best I can do for you. I cannot spend several hours designing a series of
connectors for you unless you want to pay upwards of $300-$400 for me to
design them. My focus adapter needs to come first anyway in order to free
up focus. It will not work as well further down the line.
So I guess ZMCFA ==> Lumicon 2" Newt OAG <== MFCC or Paracorr Uni wont work unless there are special adapters ...

Guess I'll stick with a guidescope for now.
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Old 24-04-2008, 02:44 AM
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I asked : I have a Baader MFCC that will be attached directly to my SLR camera via a T-ring , how do I use a TS Off Axis Guider - Radial Guider 2" - Super Low Profile with this arrangement .

My focusor is a 2" low profile crayford style focusor.

Wont the pick-off mirror / prism get in the way when the MFCC is inserted into the Off Axis Guider this way ?

ANSWER :

Quote:
Hello Ian,

I'm afraid even the low-profile TS Off Axis Guider still isn't short enough to be used with an SLR camera. The distance between the MPCC and the camera's sensor will increase so much that the image quality will suffer.

The adaptation itself requires the T2-M48 adapter from the Baader adapter range. Then the T2 thread won't collide with the prism.

Best regards,

Patrick Woitala
Telescope-Service
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Old 24-04-2008, 01:53 PM
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Thanks Ian and everyone else,
Looks like it will go in the too hard basket at the moment.
The only arrangement that would work would be Scotts link...but thats a bit to doug to spend...
Might stay with a guidescope for now...but I shall keep my mind busy on the idea!
cheers Gary
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Old 24-04-2008, 03:40 PM
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Maybe a disassembled Paracorr Visual version's optics can be used on the scope end of a Lumicon 2" Newt Easyguider , with the SLR or DSLR on the other end ???

Wonder if it is worth asking TeleView ?
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