ethanol100
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Re: long exposure not working on B+

Fri Aug 08, 2014 10:19 am

I just want to post one image using the 6s exposure mode, taking 300 images and staging them together taking always the max pixel value creates nice star trails(all done on the pi).
Image

6by9
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Re: long exposure not working on B+

Fri Aug 08, 2014 11:04 am

ethanol100 wrote:I just want to post one image using the 6s exposure mode, taking 300 images and staging them together taking always the max pixel value creates nice star trails(all done on the pi).
Pretty!
It does make me wonder how much extra you would gain with 20s exposures, as that is still no where near the effective 30 minutes you've got here. It's still on the list, but I'm not sure I'm going to get to it at the moment.
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caracol_uk
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Re: long exposure not working on B+

Fri Aug 08, 2014 5:17 pm

It all depends on what you're trying to achieve. If you're trying to create star trails then collecting a set of 6s exposures and stacking them together is ideal and will show star colour quite nicely. However, two 6s subs stacked together won't offer the same level of detail for very dim objects as a single 12s exposure. The 2x 6s subs stacked would of course have a better signal to noise ratio as this increases with the square root of the total number of subs in the stack.

While the Raspberry Pi camera isn't intended to be a replacement for a DSLR which is the usual choice when it comes to long exposure astrophotography, the Pi camera costs considerably less and this could be of interest to amateur astrophotographers just starting out, for them to see what is possible. Imagine a scenario where you wished to photograph a comet. Most don't reach much above magnitude +6 (the limit of visibility with the human eye). With a single 6s exposure you may be able to detect the nucleus, but you wouldn't detect the faint tail. With stacking you could produce a nice final image of the nucleus, but the tail would still barely be visible.

I understand it will take a while before we get more than 6s, and I really appreciate the hard work everyone has put in to this project so far. Just making my case for >6s :)

Regards
Simon

6by9
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Re: long exposure not working on B+

Fri Aug 08, 2014 5:40 pm

caracol_uk wrote:I understand it will take a while before we get more than 6s, and I really appreciate the hard work everyone has put in to this project so far. Just making my case for >6s :)
Please note http://www.raspberrypi.org/forums/viewt ... 43&t=83353 Only just over two weeks and counting before I probably stop being able to support the Pi camera, and there are higher priorities.
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caracol_uk
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Re: long exposure not working on B+

Fri Aug 08, 2014 8:20 pm

Sorry to hear that. I wish you every success in finding alternate employment. With your skill set I can't imagine you'll struggle to find something appropriate.

Simon

ethanol100
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Re: long exposure not working on B+

Sun Aug 10, 2014 3:15 pm

6by9 wrote: It does make me wonder how much extra you would gain with 20s exposures, as that is still no where near the effective 30 minutes you've got here. It's still on the list, but I'm not sure I'm going to get to it at the moment.
20s would gain much more details of weak light sources. I think 20s will boost the amount of visible stars and details. It is a feature which a relative low priority with only few users, but would be nice.

gordon77
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Re: long exposure not working on B+

Sun Aug 10, 2014 4:02 pm

ethanol100 wrote:
6by9 wrote: It does make me wonder how much extra you would gain with 20s exposures, as that is still no where near the effective 30 minutes you've got here. It's still on the list, but I'm not sure I'm going to get to it at the moment.[/quote
20s would gain much more details of weak light sources. I think 20s will boost the amount of visible stars and details. It is a feature which a relative low priority with only few users, but would be nice.
I agree, a nice to have :D
Last edited by gordon77 on Sun Aug 10, 2014 9:45 pm, edited 2 times in total.

caracol_uk
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Re: long exposure not working on B+

Sun Aug 10, 2014 7:59 pm

It's always nice to see other amateur astronomers on these forums. In fact I'm always surprised how many I come across here compared to the relatively few I meet in everyday life. I suppose we're quite an innovative lot and see the potential of the pi.

Although 20s exposures would be fantastic, If that's going to be a struggle to implement I think second best would be the ability to force ISO 1600 at 6s. Maybe that would be less time consuming to implement?

Simon

pjwalsh77b
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Re: long exposure not working on B+

Wed Aug 13, 2014 5:02 pm

Will the enhancements that allow exposure times > 1s be made available through the general software release process, or do I need to do something special to get them?

In other words, if I just do "sudo apt-get update; sudo apt-get upgrade" will I get the new code?

Thanks!

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Re: long exposure not working on B+

Wed Aug 13, 2014 7:27 pm

pjwalsh77b wrote:Will the enhancements that allow exposure times > 1s be made available through the general software release process, or do I need to do something special to get them?

In other words, if I just do "sudo apt-get update; sudo apt-get upgrade" will I get the new code?
Those changes already have been released, so just do a "sudo rpi-update"
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gordon77
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Re: long exposure not working on B+

Fri Aug 15, 2014 10:26 am

Thanks for the update working well in my program :D

I note if I use the raspistill -ss option it takes the following times to get an image

-ss 150000 (150ms) >> 700ms
-ss 1000000 (1s) >> 3.5s
-ss 2000000 (2s) >> 8s
-ss 3000000 (3s) >> 13s
-ss 6000000 (6s) >> 24s

Is this expected ?

Note I'm not complaining just curious if I have done something wrong.

gordon77

6by9
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Re: long exposure not working on B+

Fri Aug 15, 2014 1:25 pm

gordon77 wrote:Thanks for the update working well in my program :D

I note if I use the raspistill -ss option it takes the following times to get an image

-ss 150000 (150ms) >> 700ms
-ss 1000000 (1s) >> 3.5s
-ss 2000000 (2s) >> 8s
-ss 3000000 (3s) >> 13s
-ss 6000000 (6s) >> 24s

Is this expected ?

Note I'm not complaining just curious if I have done something wrong.
Yes, totally expected. Please read the rest of this thread and the comments about burst mode.
The imaging system deals in complete frames - if it's started, then it'll finish. Plus, on any mode change, the sensor has to drop one frame, and if the exposure is set to 6s then that it is how long it'll take for that invalid frame to come through.
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gordon77
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Re: long exposure not working on B+

Fri Aug 15, 2014 1:27 pm

Thanks

pjwalsh77b
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Re: long exposure not working on B+

Sat Aug 16, 2014 4:43 pm

6by9 wrote:
pjwalsh77b wrote:Will the enhancements that allow exposure times > 1s be made available through the general software release process, or do I need to do something special to get them?

In other words, if I just do "sudo apt-get update; sudo apt-get upgrade" will I get the new code?
Those changes already have been released, so just do a "sudo rpi-update"
Did the update, got the long-exposure-enabled code, thanks much.

Wolfskin75
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Re: long exposure not working on B+

Tue Aug 19, 2014 10:39 am

I still have the b and I am new here. I am hoping to work toward a solution to be able to do star trails without having to stack the photo's. I have been reading this string and I don't understand most of it. What is the problem with it not doing the star trail.

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Re: long exposure not working on B+

Tue Aug 19, 2014 12:20 pm

For star trails you need very long exposures. The Pi camera can only do up to 6s exposures which are not long enough.
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gordon77
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Re: long exposure not working on B+

Tue Aug 19, 2014 12:26 pm

jamesh wrote:For star trails you need very long exposures. The Pi camera can only do up to 6s exposures which are not long enough.
What about this ? http://www.raspberrypi.org/forums/viewt ... 6&start=63

6by9
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Re: long exposure not working on B+

Tue Aug 19, 2014 12:59 pm

taking 300 images and staging them together
It is stacking the raw images as they are produced, and then creating a JPEG of that.

There is currently no way on the Pi to produce more than a 6second exposure for a single image. As posted elsewhere, we may get it up to 20s, but that will be the absolute maximum. To get any more you will have to stack them - there is no option.
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gordon77
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Re: long exposure not working on B+

Tue Aug 19, 2014 1:23 pm

6by9 wrote:
taking 300 images and staging them together
It is stacking the raw images as they are produced, and then creating a JPEG of that.

There is currently no way on the Pi to produce more than a 6second exposure for a single image. As posted elsewhere, we may get it up to 20s, but that will be the absolute maximum. To get any more you will have to stack them - there is no option.
still star trails however produced :D

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Re: long exposure not working on B+

Tue Aug 19, 2014 2:09 pm

gordon77 wrote:
6by9 wrote:
taking 300 images and staging them together
It is stacking the raw images as they are produced, and then creating a JPEG of that.

There is currently no way on the Pi to produce more than a 6second exposure for a single image. As posted elsewhere, we may get it up to 20s, but that will be the absolute maximum. To get any more you will have to stack them - there is no option.
still star trails however produced :D
The poster specifically asked to do it without stacking.

Not withstanding the technical issues of making it work, 20s exposures on sensors like this are going to be quite noisy, perhaps too noisy to be usable.
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gordon77
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Re: long exposure not working on B+

Tue Aug 19, 2014 2:34 pm

OK, my mistake :D

gonzothegreat
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Re: long exposure not working on B+

Wed Aug 20, 2014 9:42 pm

Just getting back to this thread, thank you so much for the long exposure, really really appreciated.
Will be testing it over the next few nights :D

raspindi
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Re: long exposure not working on B+

Sun Aug 24, 2014 4:06 pm

Great work! I am now testing the long exposures, with a java api around it to connect the camera to a indi system.

i am using the "burst" mode to reduce the time to take many pictures in a row. My problem is the raw image, becomes noise after the first few images. The command i use to stream the images to my java program:

raspistill --awbgains 1,1 --nopreview --ISO 800 --timelapse 1000 --width 128 --height 128 --shutter 100000 --timeout 180000 --burst --raw --output - --awb off

(no long exposure in this command, just to check if thats the reason. The raw data seems "valid" because i can parse it, and the stream keeps synchron. just the data inside becomes noise.

Does anyone have a workaround? or a fix?

raspindi
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Re: long exposure not working on B+

Fri Aug 29, 2014 4:08 pm

somebody? ok i reproduced the problem on the command line:
when i do:

Code: Select all

raspistill  --awbgains 1,1 --nopreview --ISO 800 --timelapse 1000 --width 128 --height 128 --shutter 100000 --timeout 180000 --burst  --awb off   -o %03d_testnew.jpg
everything works as expected.

When i now include the raw option:

Code: Select all

raspistill  --awbgains 1,1 --nopreview --ISO 800 --timelapse 1000 --width 128 --height 128 --shutter 100000 --timeout 180000 --burst --raw  --awb off   -o %03d_testnew.jpg
Then the first image is ok but all folowing images are just black (the jpeg) and the raw is just noise.

Any ideas? the burst mode in combination with the raw mode would be great to use....

6by9
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Re: long exposure not working on B+

Fri Aug 29, 2014 5:00 pm

raspindi wrote:somebody? ok i reproduced the problem on the command line:
when i do:

Code: Select all

raspistill  --awbgains 1,1 --nopreview --ISO 800 --timelapse 1000 --width 128 --height 128 --shutter 100000 --timeout 180000 --burst  --awb off   -o %03d_testnew.jpg
everything works as expected.

When i now include the raw option:

Code: Select all

raspistill  --awbgains 1,1 --nopreview --ISO 800 --timelapse 1000 --width 128 --height 128 --shutter 100000 --timeout 180000 --burst --raw  --awb off   -o %03d_testnew.jpg
Then the first image is ok but all folowing images are just black (the jpeg) and the raw is just noise.

Any ideas? the burst mode in combination with the raw mode would be great to use....
Should have been fixed the other day with commit https://github.com/Hexxeh/rpi-firmware/ ... 9c9a05c2ed
However that will have dropped the burst speed as it requires the sensor to drop a frame every time it restarts (read every capture). A workaround for that is now possible (it'll be in a new post).
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