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bias exposure time for QSI WSG 683?

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12 replies to this topic

#1 turnersummers

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Posted 19 June 2017 - 03:10 PM

Hi folks. Does anyone know what the BIAS exposure time should be for a QSI WSG 683. I can't seem to find reference to it. thanks so much....


Edited by turnersummers, 19 June 2017 - 03:10 PM.


#2 xiando

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Posted 19 June 2017 - 03:15 PM

Bias frames are generally shot at the fastest exposure time a given camera will allow. So unless there's something really peculiar with the camera cited, shoot them with the fastest exposure your camera supports. If there is something really peculiar about it, I'd suggest firing off an email to the mfg or your vendor's support team


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#3 turnersummers

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Posted 19 June 2017 - 03:35 PM

Hi there. I can't find any details telling me what the shortest exposure time should be for my camera though...



#4 Stelios

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Posted 19 June 2017 - 03:44 PM

Using SGP, you can just set 0 seconds. The camera will do its best (it works).

 

However, I remember Jon Rista saying that there's a problem with taking the shortest possible bias with the ASI 1600 which is the QSI 683 clone if I'm not mixed up). Take a look and see if you can find the thread, it was interesting. 

 

<edit>: Link: https://www.cloudyni...e/#entry7928026


Edited by Stelios, 19 June 2017 - 03:55 PM.


#5 xiando

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Posted 19 June 2017 - 03:48 PM

Hi there. I can't find any details telling me what the shortest exposure time should be for my camera though...

Whatever your image capture application allows as the shortest then, I'd guess. See Stelios' well-informed reply of course, as he notes some caveats that may apply... When all else fails, punt and contact your cameras' mfg. for an authoritative statement from the horse's mouth.



#6 Stelios

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Posted 19 June 2017 - 03:55 PM

I found the link: https://www.cloudyni...e/#entry7928026

 

The bias posts should not be shorter than 0.2 seconds for properly matching with flats (at least that's how I understood it, I plan to re-read it).



#7 drmikevt

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Posted 19 June 2017 - 04:56 PM

The ASI 1600, a CMOS chip, and the QSI 683, housing the KAF8300 CCD, are very different. 

 

For Bias frames with your CCD, set your software for .001s, but check to make sure you are getting a good frame.   If not, try .01s - you should not have to use a longer exposure than that.


Edited by drmikevt, 19 June 2017 - 05:04 PM.


#8 mistateo

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Posted 19 June 2017 - 05:30 PM

I found the link: https://www.cloudyni...e/#entry7928026

 

The bias posts should not be shorter than 0.2 seconds for properly matching with flats (at least that's how I understood it, I plan to re-read it).

Unless I am mistaken, I thought this was the purpose of 'dark flats'.  I just read about those very recently when I accidentally loaded all of my dark frames as 'dark flats' in DSS.



#9 pbunn

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Posted 19 June 2017 - 06:11 PM

I believe that the fastest shutter speed on the QSI 683 is .03 sec. That I what I use for bias frames.


Edited by pbunn, 19 June 2017 - 06:14 PM.

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#10 drmikevt

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Posted 19 June 2017 - 07:23 PM

I believe that the fastest shutter speed on the QSI 683 is .03 sec. That I what I use for bias frames.

Yes, this is correct.  Setting it for faster also works, though.


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#11 DeanS

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Posted 19 June 2017 - 09:57 PM

If you are using SkyX or Maxim then you can just select Bias frames and it knows what to do as well.   And it has the correct type of frame in the fits header which is important.

 

Dean



#12 WesC

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Posted 20 June 2017 - 07:07 PM

I set the bias exposure time in TheSkyX Pro to zero-seconds with my QSI 683. That will set it to the shortest exposure time the camera can take. Works well enough for me.



#13 BenKolt

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Posted 21 June 2017 - 03:40 PM

I can confirm what others have already said.  The fastest exposure is 0.03s, according to what is listed here: http://www.qsimaging...3-overview.html.  Oddly, this is listed in the specs table as "Electronic Shutter", but then the details explain this is the shortest mechanical shuttle exposure.

 

The longest exposure is 240 minutes, which is good to know if you happen to be at a very, very dark site and have absolutely perfect polar alignment.  Otherwise I would recommend shorter frames and stacking!

 

Getting back to bias frames, I use PI and set the exposure to 0s.

 

Best Regards,

Ben




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