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Motion Detection (lightning) on SD870IS w/ Allbest 51

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Motion Detection (lightning) on SD870IS w/ Allbest 51
« on: 29 / June / 2008, 10:53:07 »
Using Fudgey's Motion Detection script

I have been searching through the forum for a while for tips on adjusting the script to take pictures of lightning, but I haven't been able to find anything helpful.  I've tried tuning the threshold, trigger delay, etc and still get nothing.  Either it doesn't take the picture, or it won't STOP taking pictures.  Has anyone had success with MD & the SD870?


Offline fudgey

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Re: Motion Detection (lightning) on SD870IS w/ Allbest 51
« Reply #1 on: 30 / June / 2008, 14:11:05 »
Start by checking that you found the correct and latest version of the script and then read & understand the documentation. Then experiment with something other than lightnings. Like, point the camera at a white wall and throw a white ball at it and try to figure why it won't trigger as easily as it does with a black ball.

Actually the first lightning shot I took with my script was just recently (we don't get that many thunderstorms around here). Nothing can make an already blown-out sky (which is what Canon autoexposure at Ev 0 tends to give during the day) one bit brighter...not even a lightning.

So, I noticed that to greatly improve catching DAYTIME lightnings (you didn't say if it was night or day so I can only assume it's day since you're having problems while others get good results with the defaults at night), you should to use CHDK overrides to set the real desired photograph exposure and use M mode (or Ev compensation -2 in P/Av/Tv mode) to severely underexpose the scene on your LCD. Do a test shot without the script to try out the overrided exposure first. During the day the lightning probably won't light up the scene very much.

I'm working on a way to do all this quickly from the script parameters but don't hold your breath, it may take a while to find the time.


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