Help please: Baader 4in1 (or similar) to replace std Skywatcher adapter?

[MikeODay]

I decided to splash out and buy a Hutech IDAS D1 light pollution filter and purchased one to fit my Baader Coma Corrector. Unfortunatley I have now discovered that the M48 Hutech filter attached to the coma corrector will not fit into the draw tube of my Sywatcher Quattro OTA. The problem is not with the filter; it has a dia of 2" and is no wider than the coma corrector.

In the image below you will see the black adapter that screws into the draw tube. The problem is that the inner diameter of the adapter is somewhat larger than 2" whilst the inner diameter of the drawtube itself is smaller than 2".

When inserted into the adapter, the Coma Corrector takes up the full length of the adapter and any filter that is attached needs to pass into the draw tube itself in order for the camera to fit flush with the end of the adapter. With the Hutech attached to the coma corrector the camera is pused out by around 6mm. Given that the inner dia of the adapter is "too big" this means that there is no firm connection between the 2" coma corrector and the adapter and it is held only loosely by just the two adapter screws.

The possible solution I have come up with is to replace the adapter with a new one that does in fact have a dia of 2", extends out from the end of draw tube by at least another ~6mm and ideally has a compression ring rather than simple screws.

The Baader 4in1 optical back looks like it might do the trick but I cannot find the exact details of the interface it presents to the draw tube.

My current Skywatcher adapter has an M54.5x1mm male thread that screws into the thread on the inside of the drawtube.

1. Has anyone successfully connected the Baader 4in1 optical back to their Skywatcher Quattro?

2. Does the "M56" thread adapter that comes with the Baader 4in1 have a male or female thread and if male, do you know its actual specifications/dimensions?

3. If I were to remove the M56 and M60 adapaters from the Baader 4in1 I understand that I would be left with an M68 thread. Does anyone have any exact specifications for this thread and does anyone know if I can get a converter from that M68 thread to the M54.5x1 thread that I need?

4. Does anyone use an alternative adapter with their Skywatcher Quattro and if so, do you know the distance between the end of the drawtube and face of the adapter (I need this distance to be in the range ~18 to 28mm in order for the comma corrector to sit flush with the end of the adpater and also be able to achieve focus with my Nikon)?

Sorry for the very long post and and all the questions but I am really stuck and would greatly appreciate any help you could give.

Cheers

Mike

[Dr_Ju_ju]

I've recently updated 2 of my SW OTA's, by replacing the stock adaptor on the drawtube with these from Modern Astronomy http://www.modernastronomy.com/shop/specials/2-adapter-with-compression-ring-for-sky-watcher-newtonians-with-m54-thread/.

If you have any questions, I've always found Bernard to be most helpful, and responds to emails quite quickly.

[MikeODay]

I've recently updated 2 of my SW OTA's, by replacing the stock adaptor on the drawtube with these from Modern Astronomy http://www.modernastronomy.com/shop/specials/2-adapter-with-compression-ring-for-sky-watcher-newtonians-with-m54-thread/.

If you have any questions, I've always found Bernard to be most helpful, and responds to emails quite quickly.

Thanks Julian. That looks interesting and would solve part of my problem for what seems a good price. The site states a focus distance of 12mm (which I assume is the distance from the end of the draw tube to the front of the adaptor and by the way is the same as the current Skywatcher adaptor) which means that If I used this I believe it would clamp down on the middle of the coma corrector some distance from the camera and whilst it would hopefully hold it firmly in the centre I still would not be able to take advantage of the extra mechnical strength that would come from the coma corrector being hard up against the face of the adaptor. I was hoping that as the Baader 4in1 is quite a bit thicker it would hold everything more firmly. Having said that, if I can't be sure the Baader will work I will not risk the money and I'll try the one you purchased.

Much appreciated.

Mike

[Dr_Ju_ju]

Hi Mike,

 

The reason I updated, was to have a firmer hold for my Baader MPCC which form the T-nose for my DSLR camera, & it works a treat... 

[MikeODay]

Hi Mike,

 

The reason I updated, was to have a firmer hold for my Baader MPCC which form the T-nose for my DSLR camera, & it works a treat... 

Thank you, that is good to know.

Do you also have problems with filters attached to your MPCC not fitting inside the draw tube?

Cheers

Mike

[Dr_Ju_ju]

At the moment, I'm not using any filters, but as the MPCC is 2" I'd have to look at a filter wheel before the MPCC, but then I may have issues not being able to reach focus.

I could add a clip filter inside the DSLR, but obviously it would be fit & leave...

[MikeODay]

At the moment, I'm not using any filters, but as the MPCC is 2" I'd have to look at a filter wheel before the MPCC, but then I may have issues not being able to reach focus.

I could add a clip filter inside the DSLR, but obviously it would be fit & leave...

The filter wheel definitely will not work for me - if I pulled the coma corrector out to fit a wheel I would be 10s of mm too far out to achieve focus.

My current idea is to try to find an adapter that will take the M68 male thread from the Baader 4in1 and convert this to the M54.5x1mm that I need to fit into the draw tube. Failing that I will go with your recommendation above.

Cheers

Mike