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  #21  
Old 04-09-2012, 05:35 PM
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As far as I am aware, the qhy9 has these specs

body to sensor 15mm
optic window 12mm
FW 18mm

With threads and the 5 mm adaptor for the filter wheel to mpcc I get 55 mm to the shoulder of the mpcc.

you have a say 10mm OAG in the system, so I would have thought that taking the 12mm optic window out would pretty much get you dead on the mpcc specs.
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  #22  
Old 04-09-2012, 05:55 PM
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Quote:
Originally Posted by Peter.M View Post
As far as I am aware, the qhy9 has these specs body to sensor 15mm
You're absolutely right. I don't know where I got these 19mm from. Probably the 8, 13mm nosepiece +6 mm sensor. The 9 is 15mm flash to the front.
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  #23  
Old 04-09-2012, 08:42 PM
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Hi Guys,
Let's re-calculate more accurately:

CCD Back focus 15mm from CCD surface to M42/0.75 screw plane -
( that is from the camera manual.)


The distance from the glass output side of the coma corrector to the front face of the camera is about 65mm.
( I measured that & it's more than expected because of my TS9 OAG )
add 15mm for the sensor chip

64 + 15 = 79 mm

subtract the length required for the Baader MPCC

79 – 55 = 24mm = too far from the required 55mm

Removing the nose piece & using an adaptor would subtract the 12mm
nose length but add say 3mm for an adaptor so only gain 9mm.
therefore 24 - 9mm = 15 mm = still 15mm too long for the Baader MPCC.

So removing the nose piece still wouldn't work.
Apart from that I don't want to remove the nose piece.
The camera is a sealed chamber which is dried with desiccant to stop condensation.
( I know many people have done that because I have seen plenty
of optical trains where there is hardly any gap between the QHY9 camera & filter wheel. )

The RCC is one solution here:
http://www.teleskop-express.de/shop/...tsabstand.html

It says:

Quote:
Standard coma correctors only offer 55mm from their T2 threads -
just and only enough for a T2 ring and a SLR camera.

The RCC 1 offers, due to its triplet lens design, 91.5mm from its T2 thread



Anyway guys - I've ordered an RCC & I may have it before the weekend.
I'll let you know how it goes.
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  #24  
Old 04-09-2012, 09:48 PM
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I trust your measurements, and those images with the RCC look good. You are measuring to the collar on the MPCC? Just because I am planning to get a TS9 OAG for a project and want to be able to use it with the MPCC.
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  #25  
Old 04-09-2012, 10:11 PM
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Quote:
Originally Posted by Peter.M View Post
I trust your measurements, and those images with the RCC look good. You are measuring to the collar on the MPCC? Just because I am planning to get a TS9 OAG for a project and want to be able to use it with the MPCC.
No - that's a point that confused me.
I was measuring to the glass inside the MPCC.
I wasn't sure of exactly where to measure it.
They talk about a collar but do you have a drawing which
shows exactly where to measure?
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  #26  
Old 04-09-2012, 10:23 PM
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I cant find any really good diagrams, but this pdf has measurement lines drawn on the dslrs to the removable collar on the MPCC so thats where I have been taking my measurements. The best diagrams are probally at the bottom (shown for visual use)




http://www.baader-planetarium.com/pdf/mpcc_e.pdf
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  #27  
Old 04-09-2012, 10:45 PM
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Quote:
Originally Posted by Peter.M View Post
I cant find any really good diagrams, but this pdf has measurement lines drawn on the dslrs to the removable collar on the MPCC so thats where I have been taking my measurements. The best diagrams are probally at the bottom (shown for visual use)

http://www.baader-planetarium.com/pdf/mpcc_e.pdf

Thanks Peter,
It says

Quote:
It is their purpose to provide the proper 55mm (+/- 1mm) spacing
between the bottom surface of the MPCC T-2-thread and the “film”-plane or the eyepiece field stop.




I just measured my MPCC &
the glass is exactly where the bottom surface of the MPCC T-2-thread is
so they are the same measurement.
Therefore my arithmetic is correct.


Yes - those pictures using the RCC are great.
If I can do half as well as those I'll be pleased.


Tell me - do you have your nose piece removed on your QHY9?
If so - aren't you worried about condensation?


Another point:
I wonder why QHY doesn't try to make the optical train shorter? e.g.

(1) They could put the electronics inside the filter wheel outside
& have a much thinner filter wheel.

(2) They could change the housing of the camera to make the sensor closer to the
optical window on the nose piece.



Camera manufacturers should realise that we all want as short an optical path as possible
to get more even illumination of the camera chip
& less mechanical bending from gravity.
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  #28  
Old 04-09-2012, 11:00 PM
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I still have the nose piece on my qhy9, I connect my oag to the focuser side of the MPCC using the filter thread. My setup is not something I would recommend. It serves its purpose for now though.
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  #29  
Old 05-09-2012, 08:15 PM
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Yeah, I've posted on the QHY forums about this - the 12mm window could surely be much flatter, and some sort of OAG solution off the filter wheel or camera would be fantastic (probably someone has a patent it though suspect)
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  #30  
Old 05-09-2012, 10:38 PM
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Quote:
Originally Posted by RobF View Post
Yeah, I've posted on the QHY forums about this - the 12mm window could surely be much flatter, and some sort of OAG solution off the filter wheel or camera would be fantastic (probably someone has a patent it though suspect)
Hi Rob,
I think the QHYs could be improved a lot.

It's not only QHY - it's all those cameras out there.
People end up with ridiculously long optical trains to get the capability they want.
Newts are not really designed for imaging unless you get that camera sensor
in very close to the secondary mirror in some way.
Some imaging Newts. have a custom flattener built in to
overcome this problem.
The RCC I have ordered will actually require a 10mm spacer to get
it working properly which is not what I wanted but it will have to do for now.
The extra 10mm will put me further away from the secondary mirror.
Maybe the Atiks with a built in filter wheel have less back focus required?

The QHY9 will do me for now as I see every night with my telescope
as an experiment & training i.e. I will get to become proficient at Maxim DL & learn a lot - I hope.
If I'm still interested in 2 years time I may upgrade to a system with a large
full frame camera but that will require different optics too & would be much more expensive.
I am also intrigued by adaptive optics but I know that you need a bright - not always available star &
a super sensitive high download speed camera to make it work.
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  #31  
Old 05-09-2012, 11:36 PM
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The unfortunate reality is wider image circles require must more expensive optics, heavier cameras, stiffer tubes/focusers, much better mounts to handle the right angle moments, etc

I still think a Newt rig set up to exploit the "sweet spot" for a given scope is hard to beat, and QHY has made CCDs available to people that otherwise might not have been able to "have a go".

Always something to lust for, isn't there
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  #32  
Old 06-09-2012, 07:56 AM
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Quote:
Originally Posted by RobF View Post
The unfortunate reality is wider image circles require must more expensive optics, heavier cameras, stiffer tubes/focusers, much better mounts to handle the right angle moments, etc

I still think a Newt rig set up to exploit the "sweet spot" for a given scope is hard to beat, and QHY has made CCDs available to people that otherwise might not have been able to "have a go".

Always something to lust for, isn't there
I quite agree Rob.
First of all you have to do well with cheaper equipment before
jumping in the deep end with high end equipment.
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  #33  
Old 06-09-2012, 12:07 PM
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Amazing delivery from TS in Germany.
I ordered the RCC at 2pm Monday & I got it at 11am Thursday!

It looks great & now have to sort out the right spacers
to give me exactly 91.5mm from the camera sensor.

cheers
Allan
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  #34  
Old 12-09-2012, 12:58 AM
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An update:
The measurement I had below of 65mm was really 55mm.
( Result of using a measuring tape instead of a proper steel ruler)
I moved my P mirror up about an inch & it all focused nicely
just above the top of the focuser.
Still - I needed the RCC.
Maxim DL didn't work again - camera connection problems.
I used Easycap & PHD guiding instead.

Anyway - I felt a bit better to have some first light data.
I have 3 minutes x 3 of LRGB &
one 10 minutes of Ha for M8 - the lagoon.
I'll have to process them into colour soon.
This was a quick process of just 2 out of the 13 sub frames:

Link to 3 minutes of luminance - one frame.
http://i262.photobucket.com/albums/i...2/m8180sf1.jpg

10 minutes of Ha through an Astronomic 7nm filter.
http://i262.photobucket.com/albums/i...lpha600s_a.jpg


I have all 5 filters in the filter wheel & I only
had to refocus for the Ha filter.

The RCC still caused some coma in the corners.
I checked & it is very close to 91.5mm from the sensor.
Maybe it needs to operate at a slightly different distance?
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  #35  
Old 12-09-2012, 06:32 AM
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My experience with flatteners is that they have a very shallow critical zone where they're effective. And it could be out quite a bit from the theoretically calculated distance. My refractor flattener and camera specs told me I needed 20mm spacer between flattener and my camera. After doing a lot of testing I found that it was actually 30mm! That's quite a difference.

Keep in mind that all of the distances/spacings they give you are plus/minus tolerances. Not sure if that can all add up to 10mm over such a short distance, though.

I have a spacer for my MPCC on my 10in newt as well. It's exactly as per the specs/numbers calculated, but it's still not quite right. I still need to test/tweak that spacing like I did with refractor. Just haven't gotten back to it yet.

What I'm getting at is that you may need to play with the spacings, say in 1mm increments both in and out of where you calculate to find the actual correct spacing.
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  #36  
Old 12-09-2012, 10:27 AM
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Thanks Troy - I didn't know that - 10mm difference!

It would be good if I could set up an artificial star with my laser
collimater inside my living room & be able to get the right lengths before going outside.
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  #37  
Old 12-09-2012, 12:55 PM
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Quote:
Originally Posted by troypiggo View Post
My refractor flattener and camera specs told me I needed 20mm spacer between flattener and my camera. After doing a lot of testing I found that it was actually 30mm! That's quite a difference.
What refractor and flattener was that? That's a hell out of specs.
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  #38  
Old 12-09-2012, 06:10 PM
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TMB92SS refractor. It sits right in the middle of specs for Orion Flattener, but still... Other specs were the camera QSI583ws. I can't imagine the camera tolerances being that far out. Doesn't matter to me really, the results are fine for me now.
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  #39  
Old 13-09-2012, 12:01 AM
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Yes that does seem strange to be 10mm out.

As for Maxim DL:
I'll have another go at it on the bench.
I may have to reload all the software.
There is something fundamentally wrong which I don't understand.
If you click on the guide camera you should not be operating
the main QHY9's imaging camera's filter wheel without asking it to do so.

There must be something completely messed up with the windows or QHY9 drivers.

Anyway I still managed to take an image of the Lagoon nebula M8 using other software.

see here:
http://www.flickr.com/photos/2471943...in/photostream

Last edited by alpal; 13-09-2012 at 06:53 AM.
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  #40  
Old 13-09-2012, 05:52 AM
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Can you be more specific about what your Maxim issue is? ie what's going on in each tab (expose/guide etc)

Camera 1 is my imaging camera, camera 2 is guide. I know that for some reason if I have "focus camera 2" selected in the expose tab, then I go into the guide tab, it will have camera 1 as the guider cam. I can only assume that whatever camera is active in the expose tab, the other one will be in the guide tab.

Do you have filter wheel set up correctly for the imaging cam and none for guide?
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