6 replies to this topic

[Surfer4329]

I’m hoping some of you smartypants people out there can help me resolve a debate I am having in my mind. I am setting up my image train for my edgehd 8” and I have already figured out my spacers and connections for my 105mm backfocus with my 0.7 reducer. Here’s the question: Where in the imaging train should my ZWO OAG-L go?

 

The 2 options I have for image train are:

1) Reducer > SCT/M48 conversion piece > 35mm spacer > Blue Fireball manual rotator > ZWO OAG-L > ZWO EFW > ASI2600MM

2) Reducer > SCT/M48 conversion piece > Blue Fireball manual rotator > ZWO OAG-L > 35mm spacer  > ZWO EFW > ASI2600 MM

 

The reason for me debating the 2 different options is because I am thinking that having the OAG-L prism closer to the imaging camera sensor could lead to more vignetting. I would imagine you are cutting off more of the light reaching the sensor the closer the obstruction is to the camera sensor. Is  the spacer between the OAG-L and the imaging camera better if i can still achieve focus on the guide camera and imaging camera?

Edited by Surfer4329, 28 April 2025 - 04:53 PM.

[Vision]

I’m hoping some of you smartypants people out there can help me resolve a debate I am having in my mind. I am setting up my image train for my edgehd 8” and I have already figured out my spacers and connections for my 105mm backfocus with my 0.7 reducer. Here’s the question: Where in the imaging train should my ZWO OAG-L go?

 

The 2 options I have for image train are:

1) Reducer > SCT/M48 conversion piece > 35mm spacer > Blue Fireball manual rotator > ZWO OAG-L > ZWO EFW > ASI2600MM

2) Reducer > SCT/M48 conversion piece > Blue Fireball manual rotator > ZWO OAG-L > 35mm spacer  > ZWO EFW > ASI2600 MM

 

The reason for me debating the 2 different options is because I am thinking that having the OAG-L prism closer to the imaging camera sensor could lead to more vignetting. I would imagine you are cutting off more of the light reaching the sensor the closer the obstruction is to the camera sensor. Is  the spacer between the OAG-L and the imaging camera better if i can still achieve focus on the guide camera and imaging camera?

 

I am in the process of doing the exact same thing and using this guide ...

[rgsalinger]

The OAG should be placed just in front of the filter wheel. Then you adjust the OAG's prism so that there is no shadow cast on you main camera images. If you place it far from the filter wheel it will be almost impossible to make it par focal with the main camera. That's the key requirement. The two cameras must be in focus at the same time when imaging. And don't worry about slight deviations from perfect focus. 

[Yomamma]

Have the OAG first

[KGoodwin]

Put the OAG right in front of the filter wheel the way it’s described on ZWO’s site.

[Old Photons]

The distance from the imaging sensor to the prism has to be the same as from the guide camera sensor.  If you don't keep the oag attached to the filter wheel you will have to move the guide camera back by 35mm.  This will be tough.  The ZWO OAG-L, EFW, and camera are all made to be attached together.

[Greg M]

Option 1 is most likely your only choice. I doubt you would be able to achieve focus on both cameras with that 35mm spacer in there as described in option 2.