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C9.25 with COAG and TV Powermate

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#1 Sitt

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Posted 01 October 2020 - 03:26 AM

I have a 2x TV Powermate that I've never used and wanting to place it in my image train for the Mars opposition but not certain on how to go about this...

I have a 9.25 EdgeHD and my backfocus is more or less perfect to my ASI533 at 146mm using the following:

 

C9.25 -> 0.7 Reducer -> Esatto Microfocuser -> Celestron OAG -> ASI 533

 

Is it best to put the PM in between the COAG and ASI533? I know that the PM is parfocal so that shouldn't affect my back focus but this would increase the distance from the prism to the imaging sensor so would I need to adjust the guide camera that same distance so both imaging and guide camera achieve focus? Or do I take the COAG out of the image train completely ?

 

If anyone has photos of their image train handy using a PM I would love to see them?



#2 james7ca

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Posted 01 October 2020 - 04:15 AM

You don't want to combine the reducer with the Powermate, so I'd remove everything and mount the Powermate directly to the rear baffle on the 9.25" EdgeHD. So, you'll need a 2" eyepiece adapter that can mount to the rear of the EdgeHD (to hold the Powermate).

 

That said, since the EdgeHD series has a required backfocus (which basically sets the mirror spacing in relation to the EdgeHD's correcting lenses) you MAY want to place the Powermate at some given distance behind the rear baffle. It doesn't have to be exact, but you probably don't want to position the Powermate so that the focus is changed significantly from what you use with your current setup (i.e. the focus that is given when your backfocus is set to 146mm).

 

There have been posts on this very topic before here on CN. You can reference the following if you want to get something that is reasonably close to ideal.

 

  https://www.cloudyni...post&p=10523904



#3 Sitt

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Posted 01 October 2020 - 06:56 AM

James, thank you. That helped greatly

 

You don't want to combine the reducer with the Powermate, so I'd remove everything and mount the Powermate directly to the rear baffle on the 9.25" EdgeHD. So, you'll need a 2" eyepiece adapter that can mount to the rear of the EdgeHD (to hold the Powermate).

 

That said, since the EdgeHD series has a required backfocus (which basically sets the mirror spacing in relation to the EdgeHD's correcting lenses) you MAY want to place the Powermate at some given distance behind the rear baffle. It doesn't have to be exact, but you probably don't want to position the Powermate so that the focus is changed significantly from what you use with your current setup (i.e. the focus that is given when your backfocus is set to 146mm).

 

There have been posts on this very topic before here on CN. You can reference the following if you want to get something that is reasonably close to ideal.

 

  https://www.cloudyni...post&p=10523904




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