Sky-Watcher .85x reducer fitting in my imaging train?

[oymd]

Good afternoon everyone.

I've started AP a few weeks ago, but have not tried to fit the matching reducer yet.

Yesterday night I took it out, and was able to screw it on the back of the scope, but on the other side of the reducer, NOTHING I had laying around or in the camera box would fit?

Any advice please?

Here's my current train without reducer:

 

And here with reducer:

 

What am I missing?

[tooth_dr]

So you need to have a distance of 55mm from the back shoulder to the sensor in your camera.

Looks like 6.5mm to the flat red surface of the camera. So you need 55-6.5mm of spacers.

The back of the 0.85x FF/FR is M48.  Get an M48-M42 adapter

https://www.firstlightoptics.com/adapters/astro-essentials-m48-to-t2-adapter.html

then measure the spacing and use your existing M42 spacers to make up the remaining.  There are different thicknesses is adapters. That one adds 10mm.

Using that example: 55-6.5-10=38.5mm

So you need an additional 38.5mm of M42 spacers.

Baader do a variable spacer. I would get the M48-M42 first, connect it and see what you have and then work our what you need. You might only need a single extension tube of 5, 7.5, or 10mm. 
 

HTH

Adam 

[Skipper Billy]

You will need spacers to connect the threads on the rear of the flattener to the front of your camera and at the same time achieving a spacing of 55mm from the aft end of the flattener to the sensor.

I dont possess the same camera or flattener but I think the camera comes with an adapter that is M54 to M48 and adds 21mm to the spacing and the sensor is reccesed by 17.5mm - this totals 38.5mm so you will need an M48 - M48 extension ring of 55mm - 38.5mm = 16.5mm to give the correct spacing.

https://www.firstlightoptics.com/adapters/astro-essentials-m48-extension-tube-set.html includes a 15mm but if you shop around you will find the 15mm on its own.

Then a set of thin spacers https://www.firstlightoptics.com/adapters/Baader_M48_adjustment_rings.html will get you to 55mm and give a bit of wiggle room for fine tuning.

Hope that helps.

 

 

 

[Skipper Billy]

Cross posted - sorry Adam.

[Skipper Billy]

It looks like Adam and I are applying the process to different cameras hence the different numbers but the principle is the same. You have to get 55mm between the flattener and the sensor.

It will also give you a screw together system that eliminates any slop or droop in the connections.

[tooth_dr]

17 minutes ago, Skipper Billy said:

It looks like Adam and I are applying the process to different cameras hence the different numbers but the principle is the same. You have to get 55mm between the flattener and the sensor.

It will also give you a screw together system that eliminates any slop or droop in the connections.

I had to go back and look through previous threads to work out the camera, think it is the right one. 

[david_taurus83]

What camera is it? Should have everything in the box?

[oymd]

2 hours ago, david_taurus83 said:

What camera is it? Should have everything in the box?

Its a ZWO ASI294MC Pro

 

[oymd]

3 hours ago, Skipper Billy said:

You will need spacers to connect the threads on the rear of the flattener to the front of your camera and at the same time achieving a spacing of 55mm from the aft end of the flattener to the sensor.

I dont possess the same camera or flattener but I think the camera comes with an adapter that is M54 to M48 and adds 21mm to the spacing and the sensor is reccesed by 17.5mm - this totals 38.5mm so you will need an M48 - M48 extension ring of 55mm - 38.5mm = 16.5mm to give the correct spacing.

https://www.firstlightoptics.com/adapters/astro-essentials-m48-extension-tube-set.html includes a 15mm but if you shop around you will find the 15mm on its own.

Then a set of thin spacers https://www.firstlightoptics.com/adapters/Baader_M48_adjustment_rings.html will get you to 55mm and give a bit of wiggle room for fine tuning.

Hope that helps.

 

 

 

My ASI294MC Pro is a 4/3 camera, so I think it comes with different adaptors.

I do not have the M54-M48

Here's what the camera comes with:

 

[oymd]

3 hours ago, oymd said:

 

 

 

 

And since we are on the topic, is my setup correct for NON REDUCER use?

I used the 2 extensions: 16.5mm & 21mm that came in the camera box, and connected them together using the M42-M48 adapter, and on one side I screwed it into the camera, and on the other I used a T adapter and nose piece that came in my Sky Watcher Evostar 80ED telescope. It slides into the back end of the focuser, and i tighten with thumb screws. I do not have a threaded connection.

[Skipper Billy]

The setup as you have it now will work just fine as long as you can achieve focus??  Personally I would add another spacer into the mix so the focuser doesn't have to be racked out so far which can cause droop/wobble.

Back to your flattener. It looks like you probably have the parts needed to get fairly close to 55mm from the flattener to the sensor. The attached drawing might help - from the parts list you posted it looks like you can get the camera end down to T2 size as well as the flattener - then just work out what you need in terms of T2 extension rings to get the correct distance or incorporate an adjustable Baader extension as Tooth Dr suggested which makes life easier.

There is a great selection of extensions here - https://www.firstlightoptics.com/adapters.html  T2 is far and away the most common size.

Dont be tempted to screw a T2 fitting onto M42 fitting - they are damn close but slightly different thread pitches - if you force them they will both be damaged.

The attached drawing gives you the distance that the sensor is rebated into the camera body to give you a start.

Once you have it all screwed together and the distance is spot on its a good idea to take it apart again and lightly smear the threads with boot polish to make sure they dont become cold welded together in case you ever want to take it apart again.

Good luck and welcome to a drawer full of redundant spacers!! 😉 

 

 

 

 

[Laurin Dave]

Should be like this for ZWO (I think) … Flattener M48 (I assume) ..  16.5 mm T2- M48 extender... 21mm T2 extender...   11mm T2 extender (on the camera already so not shown as an accessory) then camera...  giving 55mm backfocus

[oymd]

18 minutes ago, Laurin Dave said:

Should be like this for ZWO (I think) … Flattener M48 (I assume) -----> [HERE IS THE PROBLEM] <----- 16.5 mm T2- M48 extender... 21mm T2 extender...   11mm T2 extender (on the camera already so not shown as an accessory) then camera...  giving 55mm backfocus

Yesterday I tried everything i have to make an attachment to the M48 thread on the Reducer. NOTHING worked.

Edited April 8, 2020 by oymd

[david_taurus83]

4 minutes ago, oymd said:

Yesterday I tried everything i have to make an attachment to the M48 thread on the Reducer. NOTHING worked.

The 16.5mm M48 to M42 goes onto the flattener thread. Then the 21mm spacer. So you should have male threads facing the camera. With the 11mm female spacer on the camera, you should be able to attach and that gives you 55mm when you factor in the 6.5mm chip depth.

[david_taurus83]

Whats that adapter with the thumbscrew? Shouldnt need that?

[oymd]

5 minutes ago, david_taurus83 said:

Whats that adapter with the thumbscrew? Shouldnt need that?

It is a nose piece that also came in the OTA box. This nose piece goes into the back of the focuser. The thumbscrew on it has no function. It is locked to the focuser by the 2 thunbscrews on the focuser.

Ths is what my train looks like, broken down: FROM LEFT TO RIGHT. LEFT goes into CAMERA....RIGHT END goes into the focuser

16.6mm threaded into camera, then M42-M48 adapter, then 21mm spacer, then Camera T-Adapter that came in the OTA box, then a nose piece that also came in the OTA box. This nose piece goes into the back of the focuser.

Ok, so I think I am now getting to the bottom of this.

I think in my setup without reducer, I had everything setup in the opposite direction. I did get focus, and have imaged for a week or so, but was sure I had things incorrectly setup

 

[Laurin Dave]

I assume then that you don't have the 11 mm female to female T2 extender..  which makes up the distance and reverses the threads ie the black ring on the front of the camera

 

Edited April 8, 2020 by Laurin Dave

[oymd]

1 minute ago, Laurin Dave said:

I assume then that you don't have the 11 mm female to female T2 extender..  which makes up the distance and reverses the threads

ISnt that the one on the camera?

[Laurin Dave]

yes it is ..  that and the other two extenders are all you need

[oymd]

3 minutes ago, Laurin Dave said:

I assume then that you don't have the 11 mm female to female T2 extender..  which makes up the distance and reverses the threads

Do you mean this?

 

[oymd]

Just now, Laurin Dave said:

yes it is ..  that and the other two extenders are all you need

Excellent

I did what you just advised.

Will this work with focus?

 

[Laurin Dave]

yes that gives the required 55mm  ...

See link..

https://astronomy-imaging-camera.com/tutorials/best-back-focus-length-solutions-55mm.html

 

[oymd]

1 minute ago, Laurin Dave said:

yes that gives the required 55mm  ...

See link..

https://astronomy-imaging-camera.com/tutorials/best-back-focus-length-solutions-55mm.html

 

But isn't this setup:

11mm + 21mm + 16.5mm = 48.5mm?

Shouldn't it be 55mm?

[Skipper Billy]

2 minutes ago, oymd said:

But isn't this setup:

11mm + 21mm + 16.5mm = 48.5mm?

Shouldn't it be 55mm?

The sensor is 6.5mm recessed - makes it 55mm - spot on!

[oymd]

ahh...I think the missing 6.5mm is the depth of the actual sensor in the camera....

right?