Focusing a 383L+ and the OAG at the same time.

[howshaw]

I have a Atik 383L+ and EFW2 filter wheel (in the nice plastic case) and the OAG, on a Vixen VC200L scope.  The camera focuses with the telescope focuser close to its longest extension so the focuser is under quite a lot of sideways loading.

I followed the instructions quite carefully and think I have assembled everything correctly but it appears that the distance from the front of the OAG, through the EFW2 to the 383L+'s CCD is about the same as the distance from the front of the OAG through its mirror to the front face of the side mounting plate (when the OAG is fully retracted).  This means that when the 383L+ is focused the OAG focal plane is about level with the front face of the plate where my guider will fit.

If I hold a 25mm eyepiece right against the OAG side plate then the eyepiece is in focus.  However my Starlight Xpress Lodestar guide camera has its CCD some mm inside its body.

What I need is for the distance from the front of the OAG, through the EFW2 to the 383L+'s CCD to be about 15mm more than the distance from the front of the OAG through its mirror to the front face of the side mounting plate.

It would give more adjustment to the OAG if I could separate the OAG from the EFW2 by at least 15mm.  Is there an extension ring that fits between the 383L+ and the EFW2, or between the EFW2 and the OAG (or both) that would both allow me to have the focuser less extended and to focus the OAG and the 383L+ at the same time?

I could have something made, but I would rather get the proper part.

Howard.

[ruitripa]

Hello Howard,

Raise the prism holder a little. This should work.

[joelshort]

Howard,
I have the same kit as you, including the Lodestar.  In order for the Lodestar to come "close" to focus, you need to raise the prism stalk all the way up (away from the light path), and not use any of the Atik extensions on the top of the OAG.  Even so, the Lodestar is not focused, but it's close enough and good focus for a guide camera isn't essential. 

What adapter are you using between the OAG and the Lodestar?
joel

[Lex]

Hi,

I had the same issue with my Lodestar, Atik 383 and the TSOAG9,
I measured the distances from the the rear of my Coma Corrector to the CCD surface of my 383, it had to be 55 mm. So I bought some spacers to get my Guider at the appropriate distance to the prism.

I think the tolerance should allow you to under; or overstep a bit!

As being said before, perfect focus is " not so important " for the auto guider"

Best

Lex

[bwa]

Baader makes some nice fixed and adjustable spacers.

bwa

[Max]

Hi Howard

I have the same setup as you and use now the ClickLock from Bader (BA2458100) - and it fits perfect.

Thanks
Max

[Konihlav]

Hi Max,

could you please tell more about the BA2458100? I understand that it is mounted on a T2 male (as it has T2 female) and provides 1.25" sleeve for CCD or eyepiece attachment. It's optical path is from 25 to 29mm providing 4mm of focus travel. It seems to have a ring for securing the focus??? Is it rigid? does it work well?

I ask because I have BA2458125 part which is completely useless for a CCD. It is OK for a round shaped plossl eyepiece. The part doesn't have any focus lock screw/ring and even a lightweight (200g) square CCD moves the focus ring just by its weight as there's no way how to lock the focus in place.

thanks and sorry for OT.
Pavel

[chrisjbaileyuk]

For the Lodestar to come to focus you need the T2 adapter to be as low a profile as possible. I use one from Edmund Optics stock ref NT53-483 and it allows the Lodestar and 383 to come into perfect focus without messing with the prism position.

[Lex]

Hi,
I will tell you more on this the next days because my new Setup came in this afternoon :-)

Best

Lex

[Max]

Hi Pavel,

the BA2458100 is very stable because of the ClickLock system and needs no extra back focus. You mount this adapter in a direct way on the Atik OAG. Because of the ClickLock system there is no need for an extra ring. You can slide the Lodstar in and out - and then close the ClickLock system. There is no need to use the focus travel because you can use more comfortable the helical from the AtikOAG.  And yes: Its works very well and is rock stable.

I agree with you: The  BA2458125 is only for visual use.

Thanks
Max

[Lex]

Hey Max,

Is it possible to post an picture of your imaging train? I am interested in one of these Baader Clicklocks too,
to replace my actual normal eyepiece holder on my TSOAG9..

I would interest me a lot to see how you did it 

Best

Lex

[Max]

Hi Lex,

We have adverse weather - thats why the Atik is not on the scope 
And here it is:

Thanks
Max

[joelshort]

Hi Max,
What reducer or flattener do you have on there, and what's in-between the OAG and reducer?
joel

[Max]

Hi Joel

I use the CCDT67 from Astro-Physics which fits nearly perfect to the GSO RC8. This telecompressor needs 85mm distance (101mm – 16mm) from the telecompressor’s optic to the focal plane to reach f5.3 with the scope.

Because of this you can see two additional extension tube between the OAG and the reducer.

My optical train:
GSO-RC8 + AP0.67(85.5+16)mm->f5,3 + Atik OAG + Lodstar +  Atik-EFW2-1 + Atik383L+

Thanks
Max

[joelshort]

Thanks Max.  I thought that was the CCD67T.  I use that too on my AT8RC, but I just put it in front of the Atik 2" barrel.  I've calculated the reduction to yield f/5.2 with this setup.  The CCD67T works incredibly well, considering it wasn't made for this scope.
joel