Please educate me how to setup a C11 for imaging? Help please!

[oymd]

Good evening everyone, Long post, but please bear with me....

Please help me in sorting out the mess I'm in with adapters and extensions to setup my C11 for imaging.

The equipment I am trying to connect properly:

1- 2" & 3.25" Baader clicklocks.

2- Celestron .63 focal reducer. I have a 2" nosepiece that comes with it.

3- Revelation Astro 2" SCT Crayford focuser

My understanding is that there should be 110mm between the camera sensor and the focal reducer?

How can I use the above equipment to get things right?

The C11 OTA has an opening at the back that is 2"

The stock adapter that comes with the OTA has a very small aperture, that is about 1.5", a loss of 0.5"

Stock adapter on LEFT, Baader 3.25" Clicklock on the RIGHT

The Baader 3.25" clicklock has a 2" aperture, which I would prefer to use, but it extends out MUCH farther than the stock adapter

I have come up with 3 configurations:

1- Baader 3.25" clicklock ===> x.63 reducer ===> Crayford focuser ====> what to use here? ===> ASI 294MC Pro

I think in this configuration the sensor would be WAY BEYOND 110mm?

 

 

2- Stock SCT adapter ===> x.63 reducer ===> Crayford focuser ===> what to use here? ===> ASI 294MC Pro

Still, I think the crayford focuser takes it beyond 110mm

 

 

3- Stock SCT adapter ===> x.63 reducer  ===> 21mm, 16.5mm, 10mm ===> ASI 294MC Pro

Here the reducer is only 55mm from the sensor. THis is my setup for my REFRACTOR. I would very much prefer to use the Crayford Focuser to avoid as much as possible image shift and mirror flop.

This image shows the setup with the refractor's reducer, which obviously will be removed.

 

Edited April 20, 2020 by oymd

[michael8554]

If you've bought the correct focuser it should screw directly onto the back of the OTA.

The focuser must always be before the Reducer, otherwise the crucial Reducer spacing will change as you alter the focus.

The spacing for a Celestron 0.63 Reducer is 105mm.

Ideally screw it onto the focuser  instead of using a nosepiece, for rigidity.

The sensor is 6.5 mm inside the camera body, so between the Reducer and the camera you will need 105 - 6.5 = 98.5mm  of spacers.

Michael

 

[oymd]

13 minutes ago, michael8554 said:

If you've bought the correct focuser it should screw directly onto the back of the OTA.

The focuser must always be before the Reducer, otherwise the crucial Reducer spacing will change as you alter the focus.

The spacing for a Celestron 0.63 Reducer is 105mm.

Ideally screw it onto the focuser  instead of using a nosepiece, for rigidity.

The sensor is 6.5 mm inside the camera body, so between the Reducer and the camera you will need 105 - 6.5 = 98.5mm  of spacers.

Michael

 

Hi Michael

Thanks for your reply.

So, is this what you mean?

C11 OTA ===> Stock SCT adapter ===> Crayford focuser ====> Focal reducer?

Will the ZWO 16.5mm extension screw then onto the focal reducer, so the setup should be:

C11 OTA ===> Stock SCT adapter ===> Crayford focuser ====> Focal reducer===> 16.5mm ===> 21mm ===> 10mm ===> ASI294MC Pro?

[michael8554]

Yes that's the correct attachment order.

But if you read my post you'll see you need 98.5 mm of spacers.

16.5 + 21 + 10 doesn't come to that, if my mental arithmetic is correct.......?

Michael

Edited April 20, 2020 by michael8554

[oymd]

1 minute ago, michael8554 said:

Yes that's the correct attachment order.

But if you read my post you'll see you need 98.5 mm of spacers.

16.5 + 21 + 10 doesn't come to that, if my mental arithmetic is correct.......?

Michael

Sorry Michael, I'm in the process of just getting my head around how to connect them first.

I tried to attach the camera with the extenders and the thread on the ZWO extenders does not attach to the reducer.

Can you please advise what I need to add inbetween the reducer and the camera + ZWO extensions?

C11 OTA ===> Stock SCT adapter ===> Crayford focuser ====> Focal reducer===> WHAT DO I NEED HERE? ===> 16.5mm ===> 21mm ===> 10mm ===> ASI294MC Pro

I guess I will need a special adapter that will take the thread of the reducer on one side, and have enough thickness to give a total of 98.5mm, and be able to thread to the ZWO 16.5mm on the other side?

Many thanks Michael

[Laurin Dave]

Maybe try putting the clicklock on the reducer and using a nosepiece screwed into the ZWO spacer..  just position it to get roughly the right spacing.   I suspect that it will produce a lot of vignetting but at least you will find out if you can reach focus with that arrangement ..  and whether movement of the mirror means you will need an OAG for guiding 

[oymd]

1 hour ago, Laurin Dave said:

Maybe try putting the clicklock on the reducer and using a nosepiece screwed into the ZWO spacer..  just position it to get roughly the right spacing.   I suspect that it will produce a lot of vignetting but at least you will find out if you can reach focus with that arrangement ..  and whether movement of the mirror means you will need an OAG for guiding 

I actually did try that before packing up yesterday night:

C11 OTA ===> Stock SCT adapter ===> Crayford focuser ====> Focal reducer===> BAADER 2” clicklock ===> 16.5mm ===> 21mm ===> 10mm ===> ASI294MC Pro

But the camera and adapters were just telescoped into the clicklock, and overall the setup did not look right? 
 

Also, in my last picture, the reducer is being held in the crayford focuser with a thumbscrew only, and it wasn’t very secure  

 

[michael8554]

8 hours ago, oymd said:

I tried to attach the camera with the extenders and the thread on the ZWO extenders does not attach to the reducer.

The ZWO and the Reducer both have T2 threads I believe, the spacers fit the ZWO so should fit the Reducer. 

Unless those spacers are M42x1.0mm thread for Pentax/ Praktika lenses, not M42x0.75mm T2 thread.

Often they are poorly made so will sort of fit on one piece of T2 kit but not another. 

The SCT mirror focus  usually accommodates a very wide length range of kit on the back, but try with the closest to correct length you can get to if you're worried, but otherwise I don't see any point trying wrong length spacers because you'll get Coma on your images. 

T2 spacers are readily available on all Astro Equipment websites. 

Michael 

[oymd]

On 20/04/2020 at 11:22, michael8554 said:

The ZWO and the Reducer both have T2 threads I believe, the spacers fit the ZWO so should fit the Reducer. 

Unless those spacers are M42x1.0mm thread for Pentax/ Praktika lenses, not M42x0.75mm T2 thread.

Often they are poorly made so will sort of fit on one piece of T2 kit but not another. 

The SCT mirror focus  usually accommodates a very wide length range of kit on the back, but try with the closest to correct length you can get to if you're worried, but otherwise I don't see any point trying wrong length spacers because you'll get Coma on your images. 

T2 spacers are readily available on all Astro Equipment websites. 

Michael 

I need to find a FEMALE SCT to a MALE M48 adapter, but I simply cannot find one on FLO? 

The 16.5mm ZWO extender is M48 on the reducer side.

Also, with all the ZWO extenders attached, I will only have 55mm backfocus? How will I achieve the additional 50mm to reach the optimal 105mm back focus for the 0.63x reducer?

[Merlin66]

It's more normal to use the SCT female to 1.25" adaptor which comes with the SCT. This also has a T thread at the eyepiece end.

So you'd have the reducer fitted to your rear cell (or to the focuser) then the SCT eyepiece adaptor then your T thread spacers to the camera...

Looks like your focuser is a 2" size? You'll need a 2" male to SCT adaptor on the front of the reducer to fit the focuser......

https://www.firstlightoptics.com/adapters/moonlite-smooth-bore-2-inch-to-sct-adaptor.html