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QSI shutter priority

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#1 dsidote

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Posted 12 January 2016 - 03:01 PM

I have a QSI-660wsg and I was wondering if I should be changing the shutter priority in the QSI settings from mechanical to electronic when collecting lights and flats, or bias frames with the cap on. Is there any reason to worry about the life of the shutter?

 

Thanks!


Edited by dsidote, 12 January 2016 - 03:01 PM.


#2 Peter in Reno

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Posted 12 January 2016 - 04:37 PM

Are you asking for the mechanical shutter to be open at all times and use the cap to cover the camera or scope when taking dark and bias? Of course mechanical shutter needs to be open for lights and flats.

 

I don't know if you are aware of this. Many capture software allows you to control the mechanical shutter. You can tell the capture software to keep the mechanical shutter always closed for dark and bias. I am not sure if there are capture software to always keep mechanical shutter open at all times. I use Nebulosity and SGP for capturing images and I do not see an option to keep mechanical shutter open at all times.

 

I always keep mechanical shutter closed when taking dark and bias via capture software. In other words, mechanical shutter never opens for darks or bias. But for lights and flats, mechanical shutters always opens and closes.

 

Mechanical shutter is useful for remote control for taking darks and bias when you are not near the camera/scope.

 

Sony CCD in QSI 660wsg camera is interline meaning mechanical shutter is not required but QSI put it there anyway for not only for remote control for taking darks and bias but also good protection against foreign elements like dust hitting the CCD.

 

Peter



#3 Ken Sturrock

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Posted 12 January 2016 - 05:14 PM

I leave my 690 set for electronic shutter priority. This will use the electronic shutter for exposures and only engage the mechanical shutter when needed for darks (or bias frames, I guess).

 

Truthfully, I kind of set it and forgot about it, but it seems to work fine. I guess I could be missing out on something though! I had thought about Peter's point regarding protection but I leave the camera/OTA sealed up and, I believe, that the CCD lives in a sealed chamber with a window.



#4 dsidote

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Posted 12 January 2016 - 08:34 PM

Thanks, Peter and Ken.

 

Your setup is exactly what I was asking about. What got me thinking about this is that I am selling a dslr camera and I was asked how many shutter actuations it had. Dslrs have a rating for the shutter, but it seems astro CCDs with mechanical shutters do not. I never changed the default settings on my QSI so I was wondering if I was reducing the life of the shutter by always using the mechanical shutter.

 

I use SGP for automation but I haven't yet figured out if its smart enough to use the mechanical shutter for darks and bias if I set it to electronic shutter priority.

Dave



#5 Peter in Reno

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Posted 12 January 2016 - 08:42 PM

You can easily test it by looking through the camera's port and see if the shutter remains closed while taking darks.

 

Peter



#6 dsidote

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Posted 12 January 2016 - 08:47 PM

That's the plan for Friday night, the start of a week long string of cloudy nights...

 

Dave



#7 Peter in Reno

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Posted 12 January 2016 - 09:02 PM

You can test it anytime and indoors. No need to test it at night.

 

Peter



#8 andysea

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Posted 12 January 2016 - 09:05 PM

I doubt that the shutter on the QSI will ever fail. It is not a curtain shutter like on DSLR cameras. In my two QSI cameras the shutter is just a solid wheel with a window in it and a motor to activate it. You can actually see if if you open the camera and you can rotate the shutter wheel manually.


Edited by andysea, 12 January 2016 - 09:06 PM.


#9 Ken Sturrock

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Posted 12 January 2016 - 09:05 PM

Well, the shutter activation on a single lens reflex camera is a bit more violent than the relatively smooth spin of the QSI's shutter. I think the shutter is pretty durable, afterall, the full frame 683 runs it all the time and they don't seem to be failing.

 

I think another benefit of using the electronic priority is that it would help you avoid "shutter smear" when you take flats and it might also take cleaner and faster focus images. That's just a guess on my part, though.



#10 dsidote

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Posted 12 January 2016 - 09:05 PM

I know, Thusday night is supposed to be clear and I want to image with the camera. Friday I will break it down and check the shutter. I am waiting on rings for my new telescope so Thursday is probably the last time I will be using the old one.

 

Dave



#11 dsidote

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Posted 12 January 2016 - 09:07 PM

Well, the shutter activation on a single lens reflex camera is a bit more violent than the relatively smooth spin of the QSI's shutter. I think the shutter is pretty durable, afterall, the full frame 683 runs it all the time and they don't seem to be failing.

 

I think another benefit of using the electronic priority is that it would help you avoid "shutter smear" if you have to take rapid flats and it might also take cleaner and faster focus images. That's just a guess on my part, though.

 

I didn't think about that. The dslr shutter is not the same type of action. I didn't take it apart to look at it yet. In fact, the only time I had the cover off was when I initially installed my filters. I guess I am worrying for no reason.


Edited by dsidote, 12 January 2016 - 09:08 PM.


#12 Peter in Reno

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Posted 12 January 2016 - 09:26 PM

I Googled for "QSI camera shutter priority" and I found this: http://www.qsimaging...re_updates.html

 

Search for "shutter priority" and it gives good description about Mechanical and Electronic shutters.

 

It's also described in "QSI User Guide" manual. Here is a snippet:

 

"Shutter Priority: Settings are "Mechanical" or "Electronic".  This setting can only be changed on cameras with interline transfer CCDs such as the QSI 520 or 640.  In "Mechanical" priority the shutter is closed after each exposure.  In "Electronic" priority the mechanical shutter is left open unless the camera is exposing a dark or bias frame.  Electronic priority provides the highest possible frame rate when taking short exposures"

 

This should apply to Sony CCDs as well since they are also interline CCDs.

 

Peter

 

 



#13 dsidote

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Posted 12 January 2016 - 09:29 PM

Thanks, Peter!



#14 Peter in Reno

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Posted 12 January 2016 - 09:34 PM

It's funny that a while ago I created similar thread at SGP forum:

 

http://forum.mainseq...-for-darks-bias

 

It says that SGP software is smart enough to keep the mechanical shutter closed while taking darks and bias only if you select the frame "type" to "Dark" or "Bias".

 

You should be all set with SGP.

 

Peter



#15 dsidote

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Posted 12 January 2016 - 09:51 PM

Brilliant! Thanks, again.


Edited by dsidote, 12 January 2016 - 09:51 PM.


#16 Peter in Reno

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Posted 13 January 2016 - 07:52 PM

I think another benefit of using the electronic priority is that it would help you avoid "shutter smear" when you take flats and it might also take cleaner and faster focus images. That's just a guess on my part, though.

 

I am not sure if that's true. My QSI 660wsg is always set to mechanical shutter priority and I have taken flats as short as 10msec with T-Shirt flats using sunlight and I do not see any smearing. For cameras with interline CCDs and mechanical shutters, two purposes for having mechanical shutter are taking darks/bias remotely and protecting the CCD from dust. When I take flats at very fast exposure time, it first opens the mechanical shutter and then uses electronic shutter and finally after the electronic shutter is done, the mechanical shutter closes. It does not matter how long it takes for mechanical shutter to open for interline CCDs.

 

Peter


Edited by Peter in Reno, 13 January 2016 - 07:55 PM.

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#17 Ken Sturrock

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Posted 13 January 2016 - 08:08 PM

When I take flats at very fast exposure time, it first opens the mechanical shutter and then uses electronic shutter and finally after the electronic shutter is done, the mechanical shutter closes.


That makes a lot of sense.

#18 Rick J

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Posted 14 January 2016 - 12:25 AM

 

When I take flats at very fast exposure time, it first opens the mechanical shutter and then uses electronic shutter and finally after the electronic shutter is done, the mechanical shutter closes.


That makes a lot of sense.

 

With my camera SBIG not QSI that's how it works 0.001" to 0.01".  Longer than that the manual says it uses the mechanical shutter.  Both avoid shutter shadow caused by leaf shutters.  This allow flats even in bright daylight with just a "T shirt" type diffuser.  On socked in days even that isn't needed.  My best flats are taken on bright cloudy days without the "T shirt" at 0.001" or 0.002".

 

Rick




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