camera stopping issues

[Jeffrey Warren]

Pat Coyle just did a test flight in Livermore California, and he and I have been having some issues with the CHDK camera script stopping midflight. He mentioned that this time it stopped snapping photos after only 12 shots. 

I looked into the script and there is a known bug that will shut the camera down:

http://chdk.wikia.com/wiki/UBASIC/Scripts:_Unlimited_Interval_Shooting

But it's supposedly only if your shutter speed is longer than 1 second, and only for older versions (rev. 149 and less) of the CHDK. Perhaps there's still some relationship, or a separate and similar issue.

I'm going to try letting the camera run for a while to see; if we need we can write a new script that's less error-prone.

Jeff

[patcoyle]

On March 5th, the second test launch went better. The script/camera
took 117 images before it stopped.

There is a recap and links to images at:
http://wiki.grassrootsmapping.org/show/GrassrootsMappingBelizeMarch5

I'll look at the link Jeff posted about the script bug.

Pat

[patcoyle]

An update on this issue: Over the weekend, I did a few tests with the
SD 400 and the 3 batteries I have. They vary in manufacturer and age
from one acquired in January, to one marked 2/07, to another of
unknown age, but presumably older.

I need to collate the data, but the number of exposures and early stop
appears to be sensitive to battery charge – duh. However, I had not
been paying attention to this in my test flights.

However, once I put fully charged batteries in, in ground-tests I got
exposure counts of: 299,237, 289, 378, 262, 301, 279, 316, 303. The
script ran till the battery was near zero %, then stopped. In some
cases there was enough battery left to power up the camera and erase
the images, in other cases the message “change battery pack” came up
and the camera turned off.

At 10 second intervals, these range from ~44 to 63 minutes, for very
usable flight durations.

These were in conditions where the flash activated every shot. I tried
turning the flash off, but in script mode this was overridden. With it
off, presumably one would get even higher numbers of photos.

The three batteries vary in age and the initial max % shown in battery
indicator varied from: ~45, to 75, to 91%. There does appear to be an
initial problem in a few of the tests where the script stopped at 1 or
up to 33 exposures.

However, my quick takeaway is that I can get very useable durations if
I ensure the batteries are fully charged and strong enough that they
have a reasonable % max battery indication, e. g., not too old, so
don’t take full charge. It may be prudent to take a few images, maybe
up to 30, ~5 minutes, before launch to mitigate the early stop failure
mode. However, for the high percentage fully-charged batteries this
did not appear to be an issue.

Pat

[Jeffrey Warren]

This is fantastic, Pat. Could you add it to the http://wiki.grassrootsmapping.org/show/ChdkIssues page?

I'm going to start marking my batteries with stickers to keep track of which cause trouble. 

Jeff