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Old 31-05-2015, 11:28 AM
bugeater (Marty)
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QHY9 + filterwheel + OAG + MPCC?

As many of us will know, you have to place the chip of your imaging camera close to 55mm from the back glass of an MPCC. My current setup with a canon camera achieves this.

I've been looking at the QHY9 mono as a possible first CCD, but I can't find a clear answer on how this will work with the MPCC and my OAG (which is quite thin). The few posts I've found suggest it doesn't work, but this doesn't make much sense given the numbers I've found. I'm wondering if anyone can definitely tell me how much room there is to play with.

QHY-9 : 15mm
QHY CFW2 : 17mm (ultrathin) to 21.5mm (standard)
TS 9mm OAG : 9mm?

This all adds to 41 to 45.5 mm. Which means there is another 9.5 to 14 mm buffer to get to 55mm. Surely adapters etc. wouldn't use this all up? Am I missing something?
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Old 31-05-2015, 12:21 PM
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Quote:
Originally Posted by bugeater View Post
As many of us will know, you have to place the chip of your imaging camera close to 55mm from the back glass of an MPCC. My current setup with a canon camera achieves this.

I've been looking at the QHY9 mono as a possible first CCD, but I can't find a clear answer on how this will work with the MPCC and my OAG (which is quite thin). The few posts I've found suggest it doesn't work, but this doesn't make much sense given the numbers I've found. I'm wondering if anyone can definitely tell me how much room there is to play with.

QHY-9 : 15mm
QHY CFW2 : 17mm (ultrathin) to 21.5mm (standard)
TS 9mm OAG : 9mm?

This all adds to 41 to 45.5 mm. Which means there is another 9.5 to 14 mm buffer to get to 55mm. Surely adapters etc. wouldn't use this all up? Am I missing something?
The QHY9 has an optical window that goes between the camera body and the filter wheel, from memory it is 12mm or something. I got precise parts to make me an adaptor that was shorter and now run the camera without that window. It allowed me to use the tsoag9 with the cam and a mpcc.
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Old 31-05-2015, 05:22 PM
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You could try an RCC1 & Varilock spacer as I use successfully:

https://www.flickr.com/photos/247194...in/photostream


Yes - you can remove the nosepiece to get more back focus
but you'll require more power to get to the same temperature as
the peltier cooler will be heated up by the air in the filter wheel.

By the way - the QHY9 is not sealed -
there are gaps all around the connectors.
Only the internal chip has a sealed window with dry Argon gas inside.


cheers
Allan
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Old 31-05-2015, 06:15 PM
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Allan,

As I am potentially interested in a similar set up in the future, how much back focus does this set up require?

Clear skies,

John K.
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Old 31-05-2015, 06:41 PM
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Allan,

As I am potentially interested in a similar set up in the future, how much back focus does this set up require?

Clear skies,

John K.

Hi John,
as I wrote in my flickr photos:

Quote:
That now allows me to adjust the
Baader RCC for the correct 91.5mm
distance from the camera sensor to knurled ring or to whatever works best.
I used it with my 8" f6 Newt. & the whole point is that it's adjustable -
making it much easier to get right than trying to swap spacer rings in & out.

I am about to use it for my 10" f4 Newt. which is working perfectly now.
( the problem was collimation which I sorted with a Barlow + a laser )


cheers
Allan
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Old 31-05-2015, 07:43 PM
bugeater (Marty)
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Originally Posted by Peter.M View Post
The QHY9 has an optical window that goes between the camera body and the filter wheel, from memory it is 12mm or something. I got precise parts to make me an adaptor that was shorter and now run the camera without that window. It allowed me to use the tsoag9 with the cam and a mpcc.
Even with the window in the mix it still doesn't hit 55mm, though I guess adapters and such could add a bit. Do you know off hand which version of the filter wheel you have?
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Old 31-05-2015, 07:56 PM
bugeater (Marty)
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Originally Posted by alpal View Post
You could try an RCC1 & Varilock spacer as I use successfully:

https://www.flickr.com/photos/247194...in/photostream
This is the solution I've seen if you can't get the MPCC to work, but I wan't to avoid it if possible. Apart from the the added cost, knowing my luck my OTA wouldn't have enough backfocus. Also, if I have to sink more cash into corrective optics for my OTA, I'll probably just spend the money on a new OTA instead, like a Ritchey-Chretien.
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Old 31-05-2015, 08:01 PM
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Originally Posted by bugeater View Post
This is the solution I've seen if you can't get the MPCC to work, but I wan't to avoid it if possible. Apart from the the added cost, knowing my luck my OTA wouldn't have enough backfocus. Also, if I have to sink more cash into corrective optics for my OTA, I'll probably just spend the money on a new OTA instead, like a Ritchey-Chretien.

If you did that you'd have to make sure you could get a corrector for the RC.
The RCC1 & Varilock adjuster was not very expensive.
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Old 01-06-2015, 05:57 AM
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Quote:
Originally Posted by alpal View Post
You could try an RCC1 & Varilock spacer as I use successfully:

https://www.flickr.com/photos/247194...in/photostream


Yes - you can remove the nosepiece to get more back focus
but you'll require more power to get to the same temperature as
the peltier cooler will be heated up by the air in the filter wheel.

By the way - the QHY9 is not sealed -
there are gaps all around the connectors.
Only the internal chip has a sealed window with dry Argon gas inside.


cheers
Allan
I have read this around the net. And I think it stems from Theo at gama electronics. It simply has not been my experience. I run at -20 in the summer and -30 in winter. If I have to use a bit more power to get there then so be it. Please note I have not tested consumption before and after. But I am talking about real world testing.
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Old 01-06-2015, 10:59 AM
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Originally Posted by Peter.M View Post
I have read this around the net. And I think it stems from Theo at gama electronics. It simply has not been my experience. I run at -20 in the summer and -30 in winter. If I have to use a bit more power to get there then so be it. Please note I have not tested consumption before and after. But I am talking about real world testing.
I can verify Peter's use. I have seen it working and seen the results.
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