OAG Advice Please

[steve2310]

Hi

I am looking into getting an OAG and I have had a look at several the last few days. I intend to use the OAG with an Atik 383L and EFW2 filter wheel, QHY5 for guiding and flattener/s.

Now, initially, having an ATIK CCD I was pretty much hooked on getting the ATIK OAG but it seems that this does not rotate, therefore making it more difficult to find guide stars.

It seems that the Orion Deluxe (Brightstar from MA) is the way to go but I'm just wondering what adapters I'll need to go with it in order to attach my camera/filter wheel/flattener. As an aside I had to buy an Atik adapter (I think it was a M54 to M42 M-F) in order to attach my Skywatcher Flattener to the EFW2.

Just wondering if anybody else has gone down the same route and if they had to buy addtional adapters to make it all fit together?

Also, I intend to use all this with a Megrez 72 and Equinox 120ed.

Any help would be really appreciated.

Steve

[morimarty]

Hi

Have you considerd the ts9 oag, i find it very versatile. i use mine with a 10inch newt, ed80, and a sct. their are various fitting combinations ie. T adapter, eos, etc. and i have never had trouble finding a guide star though i do use a sx lodestar. Good Luck.

[steve2310]

Thanks for the reply morimarty. It's funny but just as I received your reply I happened to be looking at the TS9!! Hmmm, perhaps it was meant to be!

Thanks again, and I'll keep looking!

Steve

[Merlin66]

I hope you have enough back focus for the "stack"

The OAG should fit in front of the filter wheel....what threads/connection do you have on the front of the filter wheel?

I ended machining an adaptor from the s/w thread ( the main tube of the crayford - 55mm?) to an SCT thread...this allowed me to use all my SCT stuff including the Radial OAG. An alternative would be to use an Orion(us) 2" Prime focus adaptor, this unscrews to reveal a SCT male thread....but it has the usual possible issues of being a sloppy fit in your 2" focuser......

[steve2310]

Merlin,

To be honest being quite new astrophotography/astronomy I am not entirely sure of thread names sizes etc (but I will do my best)

I believe the EFW2 has an M54 and I recently had to buy a M54 TO M42 M-F adapter in order to attach my skywatcher flattener to the EFW2 FW (in order to use my Megrez 72).

So now, I need to work out a way (in the hope) that I can attach my skywatcher flattener to the OAG (?), and then the TS9-OAG to the EFW2 filter wheel. Nothing is ever straight forward is it?

Anybody got any ideas?

[Merlin66]

I think you'll run out of back focus....

Probably have to be focuser>OAG>Flattener>filter wheel>spacer?>Camera

Check the measurements....I think the distance from the flattener to the CCD chip needs to be 55mm.....

[steve2310]

I think you are probably right Merlin as I'm sure I've read elsewhere about the 55mm distance. Looking at your >focuser>OAG>Flattener>filter wheel>spacer?>camera order of items I'm not sure I can put a spacer between camera and flattener. The 383L screws directly to the filter wheel.

I have used the ATIK 383L and Megrez 72 with a flattener but did have to use a 2" extender in order to get focus (obviously without an OAG) but this was placed into the focuser followed by flattener>wheel>camera.

There must be some other guys on here who use OAG and the Atik 383L?? Surely there must be some way of using a flattener+OAG+ etc etc?

[Merlin66]

When you had the flattener>wheel> camera arrangement - did you achieve the 55mm spacing? If so then no additional spacer would be required......

[steve2310]

When I tried to achieve focus with the flattener>wheel>camera I couldn't achieve focus. It wasn't until I added the 2" extender that I got it to focus (but I hardly had to move the focuser!)

Apologies for my ignorance Merlin but I'm pretty new to all this.

[Merlin66]

OK.

The fastest way to check it out is to measure the distance between the flattener and the camera chip....I believe this should be close to 55mm.

Putting a spacer between the focuser> flattener doesn't make any difference to the required 55mm...

[steve2310]

Ok merlin will do (once I get home). Still need to work out a way of putting it all together if i decide to get the TS9. Problems, problems.