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QSI 5/6xx wsg on ASA N series Newton

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#1 chlopak

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Posted 21 May 2013 - 08:55 PM

Hi,

 

is there anyone in the forum you uses a QSI 5xx/6xx and wsg body with his ASA Newton (N series)?

 

Would you recommend this combination ?

 

Regards,

Ralph

 



#2 BobGillette

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Posted 21 May 2013 - 09:47 PM

Ralph,

 

Yes, I use a QSI 583wsg with 31 mm Astrodon filters on my N12, with the SX Lodestar guider (the only one that will fit with the ASA adapter.) I like the results very much, although I do see some vignetting at the corners. I just crop it out.

 

Bob



#3 chlopak

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Posted 23 May 2013 - 09:27 PM

Hi Bob,

 

thanx for your answer - which surprises me a little. Why do you crop? Can't you correct the vignetting with flats? Or are the corners really shadowed by the ASA adapter? According to the QSI homepage the camera shouldn't have problems with f/3.6.

 

Regards,

Ralph

 



#4 BobGillette

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Posted 24 May 2013 - 11:21 PM

Hi Ralph,

I probably could correct the vignetting with flats, but lacking any other reason, I've never bothered with flats. Laziness, I guess.

Bob

#5 wemartin

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Posted 03 July 2013 - 10:24 AM

Hi Ralph,

I have a QSI 532ws with standard 1.25" Astrodon filters on a 16N/Wynn 3". One corner of the frame shows vignetting with this smaller chip and the focal distance is smaller than the wsg version so I would recommend the 31mm filters Bob is using. Flats remove the slight vignetting. There is, I think, a small problem with the corrector and high precision flats which I am trying to track down. More on this when I pin it down and discuss it with Phillip.

Bill

#6 chlopak

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Posted 07 July 2013 - 09:24 PM

Hi Bill,

thanks for the information!
This is now very interesting, both you and Bob actually shouldn't face any vignetting according to the statements and technical drawings from QSI. I wonder what is the reason for the vignetting both of you are reporting?

Regards,
Ralph

#7 wemartin

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Posted 15 July 2013 - 10:20 AM

Hi Ralph,

 

I've just changed the filters to the 31mm versions but my mount is being upgraded so I can't tell you how they work.  From the 1.25" filters it looks as if the CCD chip may be slightly off centre from the mechanical/optical centre of the 16N Wynne corrector.  This could be a simple external misalignment problem from my initial collimation attempts but I won't be able to confirm this for a while.

 

I have confirmed the corrector problem with flats and discussions are under way.

 

Kind regards

 

Bill



#8 wemartin

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Posted 11 December 2013 - 07:39 PM

Hi Ralph,

If you are still interested, the 31mm filters, a good collimation, and the vignetting is not detectable apart from a slight (~5%) roll-off at the edges in a QSI flat field frame. This is entirely corrected by the flat field process to less than +-1% over the whole frame. I've done this with both sky flats and with a EL panel with no surprises.

Bill

#9 Benoit Gagnon

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Posted 28 September 2016 - 02:22 AM

Ralph,

 

Yes, I use a QSI 583wsg with 31 mm Astrodon filters on my N12, with the SX Lodestar guider (the only one that will fit with the ASA adapter.) I like the results very much, although I do see some vignetting at the corners. I just crop it out.

 

Bob

What ! In 2014 iI was told by ASA that it was impossible for them to make an adaptor less than 10mm for a 12N ( that I was going to buy) and my QSIwsg-8 with Astrodon filters. Where did you have your adaptor made? I have the email from ASA if you want . ps the adaptor was for the Wynne corrector. 


Edited by Benoit Gagnon, 28 September 2016 - 02:22 AM.


#10 MarkS

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Posted 28 September 2016 - 06:29 AM

If I read the QSI specs correctly, the backfocus distance is  50.2 mm for the QSI683swg-8. and T-mount.

 

The ASA 3" Wynne requires 57.3mm optical. If the 50.2mm quoted by QSI is physical, then you have 8.4mm as the required adapter thickness, assuming 4mm total glass thickness between sensor and corrector.

 

It is just possible to make an adapter this thin - though ASA may not be tooled up for it. The 8.4 mm thickness gives just enough depth to contain a M3 bolt head plus a reasonable seating thickness. You may be able to find a CNC mahine shop that could and would do it. (I have access to such a facility, which makes all my adapters)

 

You need to check very carefully whether the QSI backfocus depth specified is physical or optical, and, if the latter, what the assumed glass thickness is for coverglass and filters.

 

There isn't much latitude for best performance. Philipp Keller told me some time ago you need to be within +/- 0.5mm. I like to have the distance accurate to machine tolerance.

 

Mark






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