Space Balloon - page 2 - Script Writing - CHDK Forum
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Space Balloon

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Offline dcshrum

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Re: Space Balloon
« Reply #10 on: 13 / October / 2008, 14:05:21 »
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Actually the GAS isn't too expensive.  I think our helium cost will be about $50.00, hydrogen would be half that with not much more lifting capacity and the added danger so we will probably go with helium. 

Uballoontu   Has details on my project.

Now for the question --

I have a simple script.  It just takes pictures until the SD card is filled up.  I am thinking I need a faster shutter speed as the payload will likely swing around.  Can I set that from the script?  Really I don't know diddlie squat about photography.  Seriously, I'm reading the wikipedia article on shutter speed right now :)  Suggestions for settings I should put in here to increase my odds of getting a few cool shots out of this?

@title Shoot to the Death

@param a Interval (Minutes)
@default a 0
@param b Interval (Seconds)
@default b 1
@param c Interval (10th Seconds)
@default c 0

t=a*60000+b*1000+c*100

if t<100 then let t=5000

n=1

print "Shoot until I die"

sleep 1000

goto "shot"

:shot
  shoot
  n=n+1
  sleep t
  goto "shot"
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Offline zeno

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Re: Space Balloon
« Reply #11 on: 13 / October / 2008, 17:06:29 »
You might want to talk to Doug Ellison who used a CHDK'd A560 - see
    missions:haps:haps-1    [Pegasus HAB Project]
  for details including pointers to movies and stills
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A570, S100, Ixus 127
Author of ASSIST, STICK, WASP, ACID, SDMInst, LICKS, WICKS, MacBoot, UBDB, CFGEdit
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Offline fbonomi

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  • A570IS SD1100/Ixus80
    • Francesco Bonomi
Re: Space Balloon
« Reply #12 on: 13 / October / 2008, 18:49:08 »
Quote from: dcshrum on 13 / October / 2008, 14:05:21
Can I set that from the script?  Really I don't know diddlie squat about photography.  Seriously, I'm reading the wikipedia article on shutter speed right now :)  Suggestions for settings I should put in here to increase my odds of getting a few cool shots out of this?

The simplest and probably most effective way is to use shutter priority (see Wikimedia Error for some more detail)

Basically, you would say to the camera: shoot at 1/1000th of a second, and adjust aperture accordingly.

By looking at the photos of the HAPS missin (here Index of /HAPS1/PHOTOS ) it seems that they used a completely opposite approach, aperture priority, (see Aperture priority - Wikipedia, the free encyclopedia) as all the photos have an aperture of F 7.1.

This means thet said to the camera "keep the the diaphragm at F 7.1 and adjust shutter speed accordignly".

(EDIT: researching better the argument, this turns out not to be true.)

This means that high-altitude images (where there's lots of light) have come out with a shutter speed of 1/1000th of a second (see for example the EXIF data of IMG_6622.JPG) while lower-altitude images needed a longer exposure and are therefore rather blurred. See for example http://www.umsfbu.com/HAPS1/PHOTOS/IMG_5824.JPG with a shutter speed of 1/250)

Maybe I am wrong, but I cannot understand their choice...

The bad news is... as far as I understant the SD1100 does not have a shutter priority mode (and dos not have an Iris either, I suspect)....

This does not mean we can't use it, just that we'll have to program a sort-of shutter priority mode via CHDK. It would be a bit more complex but we could add some extra functionalities, such as:
- increase ISO if shutter time goes above a certain time (avoid blurred images if it's dark)
- use extra-short exposures (well below the minimum 1/1500 that the original firmware has)

In my script for time-lapses (Timelapse with variable shutter speed) I am doing something quite similar: measure luminosity of the scene and adjust exposure (shutter, aperture and ISO) according to our tastes.

I would be pleased to help you with this project, but I don't have an SD1100.

Also, what exactly is the state of CHDK support for the SD1100? is it really bas as it says here: Firmware Comparisons - CHDK Wiki ?

Would you be open to changing camera? For example, my A570 is 220 grams (7.7 ounces) batteries included. I read you camera is 6.5 ounces... would that be a problem? If that's ok, I would love to do the script for your project.

If you really want to stick to the SD1100, I would need to find one, but I don't know how easy would that be.
« Last Edit: 27 / October / 2008, 10:13:34 by fbonomi »
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Offline will

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Re: Space Balloon
« Reply #13 on: 14 / October / 2008, 00:38:07 »
Quote from: fbonomi on 13 / October / 2008, 18:49:08
The bad news is... as far as I understant the SD1100 does not have a shutter priority mode (and dos not have an Iris either, I suspect)....

You're right, it doesn't have an iris. Aside from the shutter speed override via CHDK (which does work), it has no shutter priority mode.

Quote from: fbonomi on 13 / October / 2008, 18:49:08
Also, what exactly is the state of CHDK support for the SD1100? is it really bas as it says here: Firmware Comparisons - CHDK Wiki ?

Would you be open to changing camera? For example, my A570 is 220 grams (7.7 ounces) batteries included. I read you camera is 6.5 ounces... would that be a problem? If that's ok, I would love to do the script for your project.

If you really want to stick to the SD1100, I would need to find one, but I don't know how easy would that be.

I'm not sure the A570 is on sale anymore, the A590, which I believe is the successor has some work being done to port CHDK to it. Here's the thread with people working on it: A590IS Porting, who's with me?

Or even the A720 (if you can find it). I believe the A720 is out of production, so whatever is left on shelves is all there is.

As for the current state of the SD1100 port? From what I can see, it's pretty stable with not many bugs left.
chr just posted another release which is based on the latest CHDK code. SD1100/ixus 80 porting ....
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Offline zeno

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Re: Space Balloon
« Reply #14 on: 14 / October / 2008, 04:45:55 »
Aside from aperture setting, the other advantage of the A560, A570 and A720 is that it's possible to switch between still and movie mode under script control (as used by HAPS) - using my special builds here CHDK Mode Dial Support
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A570, S100, Ixus 127
Author of ASSIST, STICK, WASP, ACID, SDMInst, LICKS, WICKS, MacBoot, UBDB, CFGEdit
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Offline fbonomi

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    • Francesco Bonomi
Re: Space Balloon
« Reply #15 on: 14 / October / 2008, 08:53:21 »
Quote from: zeno on 14 / October / 2008, 04:45:55
Aside from aperture setting, the other advantage of the A560, A570 and A720 is that it's possible to switch between still and movie mode under script control
Oh, I didn't think about that. That's importanto too...
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Offline dcshrum

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Re: Space Balloon
« Reply #16 on: 16 / October / 2008, 17:13:10 »
Quote from: fbonomi on 13 / October / 2008, 18:49:08

Would you be open to changing camera? For example, my A570 is 220 grams (7.7 ounces) batteries included. I read you camera is 6.5 ounces... would that be a problem? If that's ok, I would love to do the script for your project.

If you really want to stick to the SD1100, I would need to find one, but I don't know how easy would that be.

Ok -  Actually what you are saying makes perfect sense.  We do want to use shutter speed priority because in those cases where the camera is swinging around you would want a high shutter speed with an aperture adjusted to allow for proper exposure, doing the converse would make no sense at all. 

It turns out I have another problem.  Battery life seems to be about 2 hours for 1650 pictures.  I have a .760 amp hour battery.  I can buy a 1 amp hour battery for about 16 bucks so that may be the best solution and would in theory give me maybe 40% more time.  My fear is that extreme cold will shorten the battery life and my planned flight time is right at two hours.  It would be nice to turn off the LCD.  All the reading I've done indicates I can't really do that.  I did turn off the flash.  I suppose a plug into the AV port wired for a loopback may improve things.  It would be nice to just turn off the LCD after the first 10 pictures or something though. 

It would be really cool to take X pictures followed by a few minutes of video.  I read a little on that as well and it seems there is no solution.

As for switching cameras....  I'd like to use the lighter one.  Literally an ounce makes a difference.  You should see us stripping plastic off components :)  In addition my wife will actually kill me if I spend more money on this.  It looks like you are in Italy so I don't suppose I can just mail you my camera as that would cost more than the darn camera. 

http://www.google.com/products/catalog?q=sd+1100&oe=utf-8&cid=15179051455996785181#ps-sellers

Can you think of some way to work on it from my desktop?  I can let you ssh into my desktop and hack away if you can do anything via the USB cable.

My junk email account is donald_shrum@yahoo.com  Drop me a line and I'll respond witht he email address I don't want posted on public bulletin boards for the spammers to hack at :)

Thanks for any help!

Phase two of the project is a rockoon.  Assuming I get my payload back I'll be launching a rocket to 120K feet with three balloons and then lighting up the rocket at altitude for some cool nasa like video as the rocket heads towards space.  I'm corresponding with some amateur rocket guys on that project. 
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Offline BHPete

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Re: Space Balloon
« Reply #17 on: 19 / October / 2008, 13:05:29 »
Here is a balloon script for a Canon A570is:  Canon A570 IS Scripting setup

Here is one photo I got from my one HAB flight: 

That script needs some work to compensate for the extremes in exposure.

Here are some much better pictgures from a High Altitude Balloon flight in Alaska:
BEAR Balloons
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Offline aharfo56

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Re: Space Balloon
« Reply #18 on: 02 / March / 2010, 09:39:05 »
Actually, you can!  I'm working to put a project like this together as well.  With a bit of luck and lots of planning, my university will take to the idea and we can start a class in "high altitude near-space photography" or something like it.  I have had to change a few things (the cellphone GPS will likely get lost, as I live in a rural area with sparse coverage; I purchased a SPOT GPS unit which uses the satellites directly vs. using the cell towers and GPS.), but it is coming along nicely.  I'm eager to go to near-space AND BEYOND!  :-)
Quote from: rastetter on 10 / October / 2008, 21:38:04
That sounds like an awesome idea... wish i had a damn space balloon.
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