napajedlaci.cz
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Raspistill when photographing 5,9s lasts up to 36 seconds, w

Sun Jul 10, 2016 8:45 pm

Night shots during -ss 5900000 -ISO 500 raspberry lasts 2 to photograph and process for 36 seconds :roll: . Why does it take so long?

I expected that I would shoot every 30 seconds, but it probably will not. :cry:

gordon77
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Re: Raspistill when photographing 5,9s lasts up to 36 second

Sun Jul 10, 2016 9:20 pm

It takes approx 4 times the exposure time due to the number of frames it needs to take.

If you set -bm (burst mode) it will be quicker after the first shot.

napajedlaci.cz
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Re: Raspistill when photographing 5,9s lasts up to 36 second

Mon Jul 11, 2016 9:06 am

The command will look like that? Somehow I can not find -bm through google. If the day trying --burst, so the change does not occur at any speed.

jamesh
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Re: Raspistill when photographing 5,9s lasts up to 36 second

Mon Jul 11, 2016 9:13 am

To take one picture, the system needs to:

Turn off preview. Start sensor in full frame mode. Wait for the first complete frame, which is usually discarded as corrupt. Then grab a few frames for AWB/AGC. Note each frame takers 5.9s to get. Take image. Go back to preview mode.

So, once all that is taken into account, you can easily get to 30s or so.
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gordon77
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Re: Raspistill when photographing 5,9s lasts up to 36 second

Mon Jul 11, 2016 11:15 am

napajedlaci.cz wrote:The command will look like that? Somehow I can not find -bm through google. If the day trying --burst, so the change does not occur at any speed.
You can't do it with a single shot, look at time-lapse with -tl and set it to take several shots, add the -bm option.

pfile
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Re: Raspistill when photographing 5,9s lasts up to 36 second

Wed Jul 13, 2016 5:58 pm

i had the same question about the exposure lengths - would it make sense to have an option to just turn off all of those pre-frames if the exposure length is > some threshold? if you need to capture one frame and throw it away, can it be done at a shorter exposure? and for night photography AWB seems un-necessary. as for AGC, if the gain were exposed to the user we could just set it manually to whatever it needs to be for unity gain, or whatever works out best for the application.

as it stands right now i can only take one image every 45s when the exposure length is set to 5.9s.

thanks

6by9
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Re: Raspistill when photographing 5,9s lasts up to 36 second

Wed Jul 13, 2016 7:39 pm

pfile wrote:i had the same question about the exposure lengths - would it make sense to have an option to just turn off all of those pre-frames if the exposure length is > some threshold? if you need to capture one frame and throw it away, can it be done at a shorter exposure? and for night photography AWB seems un-necessary. as for AGC, if the gain were exposed to the user we could just set it manually to whatever it needs to be for unity gain, or whatever works out best for the application.
Feel free to go and write your own app. raspistill can't be everything to everyone - it's just impossible.

In theory if you enable ONLY the stills port via MMAL, then you should be able to avoid the initial 2 frames used to feed preview, but you MUST specify exposure time and hope that analogue and digital gains are set to something sensible (I'm not sure -ISO will set things up as AGC is locked for stills captures). Adding -st for a stats pass would sort out AWB and digital gain for you.
pfile wrote:as it stands right now i can only take one image every 45s when the exposure length is set to 5.9s.
If you ignore timelapse mode and burst mode, then yes. Otherwise you should be able to achieve at least every 12secs, and if using raspividyuv you should get every 6 secs.
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pfile
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Re: Raspistill when photographing 5,9s lasts up to 36 second

Wed Jul 13, 2016 7:54 pm

i would use the burst/timelapse mode except for the fact that it seems to not want to hold the shutter open for more than 1/10 of a second or so if -ss is not specified. the application is for an all sky camera where the exposures vary from 200uS to 5.9s throughout the day, so letting raspistill manage the exposure won't work. having said that i'm starting to think it would be impossible - the initial gain/wb calculated at midday would probably be completely wrong for midnight. i guess i could monitor the images and kill/restart raspistill with a new shutter speed as night falls.

a 45-second interval is not the end of the world for this application but i started thinking about speeding things up for more general astrophotography applications and noticed this thread.

gordon77
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Re: Raspistill when photographing 5,9s lasts up to 36 second

Wed Jul 13, 2016 8:08 pm

" i guess i could monitor the images and kill/restart raspistill with a new shutter speed as night falls."

Why not do that, take the average value of the photo and set the values for raspistill including iso, shutter speed, ev or brightness, mode eg night, auto etc?

pfile
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Re: Raspistill when photographing 5,9s lasts up to 36 second

Wed Jul 13, 2016 8:14 pm

gordon77 wrote:" i guess i could monitor the images and kill/restart raspistill with a new shutter speed as night falls."

Why not do that, take the average value of the photo and set the values for raspistill including iso, shutter speed, ev or brightness, mode eg night, auto etc?
that's what i'm currently doing... i pick an exposure, compute the mean of the jpeg that came off the camera (using convert) and scale the exposure by log(mean)/log(0.5), after some error checking of course. also, i peg the exposure at 5.9s. this seems to work well.

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