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Auto Long-time Exposure

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Auto Long-time Exposure
« on: 16 / May / 2011, 21:36:49 »
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I was wondering how you set up your camera so that it uses auto exposure and can automatically choose 1"+ exposure times, hopefully even more than 15". When I set my camera to force a long exposure time via the chdk, when I go to take a picture at night, my camera goes into a mode that actually does do an automatic long time exposure up to 15", but it doesn't matter because I am forcing a particular exposure already. So it's not actually automatic.

In effect, this setting is unlocking longer exposure times, but forcing a specific one which I don't want.

The purpose I want this for is to do time lapses during night, all the way through to daytime. As it is now, I can force it to go all the way to 64" exposure, but as soon as the sun comes up it's worthless because it just turns white obviously.

My camera is the SD750, I am running ixus75_sd750-102a-0.9.9-1188-full. I have heard of people doing nature time lapses for days so I assume this is possible, I just can't figure out how. I use the main intervalometer, "ultra intervalometer" I think... and I like it and I think it is probably possible to do what I am trying to accomplish with it but I don't know how...

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Offline reyalp

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Re: Auto Long-time Exposure
« Reply #1 on: 16 / May / 2011, 21:57:59 »
There are already some scripts that do this, search for "night time lapse". Here's one http://chdk.setepontos.com/index.php/topic,1145.msg11090.html#msg11090
Don't forget what the H stands for.

Re: Auto Long-time Exposure
« Reply #2 on: 17 / May / 2011, 16:46:24 »
Thanks, I looked into a bunch of intervalometers, including the night one you showed. However, these will not suit my needs because its appears the best they can do is adjust for a sunset... but not back up again. As soon as the light comes back they just turn white.

There has to be one that can accomplish this feat... Otherwise I guess I will just have to learn how to make my own and post it

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Offline reyalp

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Re: Auto Long-time Exposure
« Reply #3 on: 17 / May / 2011, 16:56:26 »
Thanks, I looked into a bunch of intervalometers, including the night one you showed. However, these will not suit my needs because its appears the best they can do is adjust for a sunset... but not back up again. As soon as the light comes back they just turn white.
This is not correct.
Don't forget what the H stands for.


Re: Auto Long-time Exposure
« Reply #4 on: 17 / May / 2011, 17:36:45 »
Hmmm well I did some more looking... I had originally not tried the script you posted because the ensuing comments said that it wouldn't work for a sunrise, and instead opted to try the main CHDK script page, which I thought would be the most up to date and have the best scripts. I was wrong. I tried almost every intervolameter listed and none of them work.

I tried the one you posted though and have found that it will, in fact, work. It looks like that original post was edited and kept up to-date with further advancements in the script... So I should have tried that one specifically first, but you can understand why I didn't... Anyway thank you for your help! Hopefully this will work pretty well

 

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