JovianPyx
Posts: 132
Joined: Fri Nov 20, 2015 9:34 pm

HQ Camera Exposure Longer Than 200 Sec

Thu Jun 18, 2020 6:13 pm

I've just received my HQ camera which I've purchased to use mainly for astrophotography. Reading through posts here, I can't find a way to use the camera in bulb mode, that is, where the shutter is opened manually and it remains open until it is manually closed. Such as for photographing a meteor shower.

I am assuming that the 200 second limit is built into raspistill and is not a function of the camera hardware. Is that true? If so, is there 3rd party software or raspistill variant code I can compile?

I don't see python controls for shutter open and shutter close.

I apologize if this is an already asked question, some days my search-foo is better than others. If so, please link me to the post.

Thanks for any information.

jamesh
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Re: HQ Camera Exposure Longer Than 200 Sec

Thu Jun 18, 2020 8:50 pm

Its actually a function of the sensor - a limit on the timings you can set it to. These timings set the values for the rolling system system, i.e. how long a line is exposed for. I think the upper limit is about 230s before the registers for timing parameters reach the maximum possible.

So, no infinite bulb function.

Stacking is the way to go. Just keep taking multiple 200s exposures.
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HermannSW
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Re: HQ Camera Exposure Longer Than 200 Sec

Thu Jun 18, 2020 9:54 pm

jamesh wrote:
Thu Jun 18, 2020 8:50 pm
I think the upper limit is about 230s before the registers for timing parameters reach the maximum possible.
The exact value is just above 239s.

Details on how to do 239s long exposures (with raspistill or raspiraw) here:
viewtopic.php?f=43&t=277397&p=1680052#p1680052
Stacking is the way to go. Just keep taking multiple 200s exposures.
Three consecutive raspiraw 237s exposures (always 1 led lit for 4s, from top to bottom, left to right => loops after 256s):
Image
https://stamm-wilbrandt.de/en/Raspberry_camera.html
https://stamm-wilbrandt.de/en#raspcatbot
https://github.com/Hermann-SW/raspiraw
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://stamm-wilbrandt.de/working_with_FPGAs

JovianPyx
Posts: 132
Joined: Fri Nov 20, 2015 9:34 pm

Re: HQ Camera Exposure Longer Than 200 Sec

Thu Jun 18, 2020 10:02 pm

jamesh wrote:
Thu Jun 18, 2020 8:50 pm
Its actually a function of the sensor - a limit on the timings you can set it to. These timings set the values for the rolling system system, i.e. how long a line is exposed for. I think the upper limit is about 230s before the registers for timing parameters reach the maximum possible.

So, no infinite bulb function.

Stacking is the way to go. Just keep taking multiple 200s exposures.
Thank you, this is great information.

Can I ask if there is suggested software for doing the stacking?

ncysys
Posts: 3
Joined: Thu Jun 18, 2020 5:17 pm

Re: HQ Camera Exposure Longer Than 200 Sec

Thu Jun 18, 2020 11:14 pm

Hi , Here is a link to an article for stacking astro photography exposures.

https://astrobackyard.com/deep-sky-stacker-settings/

JovianPyx
Posts: 132
Joined: Fri Nov 20, 2015 9:34 pm

Re: HQ Camera Exposure Longer Than 200 Sec

Fri Jun 19, 2020 12:46 am

Thank you, Deep Sky Stacker looks great!

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