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Exposure time/shutterspeed using intervelometer

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Exposure time/shutterspeed using intervelometer
« on: 21 / October / 2011, 18:28:43 »
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Hello,
Some friends and I are working on a space balloon project. We are using CHDK for these photographs, and an intervelometer taking a picture every 4 seconds. We are working on adjusting the shutter speed, in order to find what will work best to get clear pictures and to get enough light to get  picture. The issue we are having is currently, on the ground, we are using a shutter speed of 1/35 of a second, which is producing extremely dark photos in a bright room. we are walking slowly to take the pictures, and the photos are clear. But the brightness seems strange. We adjust to about 1/10 of a second and it still is not producing that bright of photos and they become blurry while walking and taking the photo. I am just curious for anyone that know what a good shutter speed choice would be. From reading up on the kids from MIT that did this, they used a shutter speed of 1/800 of a second. I don't see how that would work at all because the pictures are just black when we do that. Considering it would be darker up higher I just don't think it would work. Any pointing in the right direction would be much appreciated.
thanks,
Jamie

Re: Exposure time/shutterspeed using intervelometer
« Reply #1 on: 22 / October / 2011, 07:00:25 »
they used a shutter speed of 1/800 of a second.

That is about right, we used 1/1000 sec.
The balloon is moving very violently in the high wind.

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Any pointing in the right direction would be much appreciated.

I went to the trouble of posting the project script for you recently.

Re: Exposure time/shutterspeed using intervelometer
« Reply #2 on: 23 / October / 2011, 16:14:55 »
Yes, thank you again for the script. It is working and is taking a picture at the interval we chose. However, the issue isn't the script, it is the lighting. The pictures are black, in a lighted room, when using a shutter speed of 1/100 of a second. When it is in up in the air I doubt it will be as light as in a lit up room, so I see this as an issue. It could be the camera, or maybe it is some other setting that I am unaware of. I tried altering the ISO value, but the improvement was not as significant as I would have liked. Any thoughts on what is going on? or is this normal?

Re: Exposure time/shutterspeed using intervelometer
« Reply #3 on: 23 / October / 2011, 16:57:03 »
However, the issue isn't the script, it is the lighting.
What does the picture look like of you take one normally in the same room ( i.e. not with a script).  If that is bad too then your camera has a problem.

I assume you realized that the script posted will only work on SDM - not CHDK ?



« Last Edit: 23 / October / 2011, 17:03:51 by waterwingz »
Ported :   A1200    SD940   G10    Powershot N    G16


Re: Exposure time/shutterspeed using intervelometer
« Reply #4 on: 23 / October / 2011, 23:25:48 »
If I don't use any shutter speed overrides then the picture looks normal, regardless of using any scripts. But the moment I alter the shutter speed, regardless of using a script, if the shutter speed is low then the lighting is poor. However, if I go to 1/50 of a second, even if I am moving at the pace of a gentle head turn the picture is still clear. This results in a medium darkness. Not bright, but not dark.

Re: Exposure time/shutterspeed using intervelometer
« Reply #5 on: 24 / October / 2011, 05:07:32 »
The pictures are black, in a lighted room, when using a shutter speed of 1/100 of a second.

Nothing unusual about that.

Quote
When it is in up in the air I doubt it will be as light as in a lit up room

In that case, the sun must have become considerably dimmer.

The Earth is illuminated by uninterrupted sunlight.

For the reasons I mentioned, a very fast shutter speed is required in order to avoid blurred images.

1/100th of a second is not remotely fast enough.

Re: Exposure time/shutterspeed using intervelometer
« Reply #6 on: 24 / October / 2011, 09:00:51 »
The pictures are black, in a lighted room, when using a shutter speed of 1/100 of a second.

Nothing unusual about that.

Knowing the shutter speed but not knowing the ISO setting,  aperature or ND filter position makes it impossible to comment about whether you should see a black image or a washed out white image in a lit up room.    What ISO, aperature setting and ND filter position is selected when you are doing these test pictures ?
Ported :   A1200    SD940   G10    Powershot N    G16

Re: Exposure time/shutterspeed using intervelometer
« Reply #7 on: 24 / October / 2011, 09:33:02 »
I can assure you that indoors the Canon firmware will have forced the ND out.
You have to point the camera directly and very close to a tungsten light for the ND to be in.
The user would have had to force it in for some reason.

The SDM script also forces the shutter out to give a fast shutter speed.


Re: Exposure time/shutterspeed using intervelometer
« Reply #8 on: 24 / October / 2011, 09:39:37 »
I can assure you that indoors the Canon firmware will have forced the ND out.
You have to point the camera directly and very close to a tungsten light for the ND to be in.
The user would have had to force it in for some reason.
The SDM script also forces the shutter out to give a fast shutter speed.
So what ISO and aperature value is the camera using ?  I'm learning that overrides do not always play well when the rest of the camera is in AUTO mode.
Ported :   A1200    SD940   G10    Powershot N    G16

Re: Exposure time/shutterspeed using intervelometer
« Reply #9 on: 24 / October / 2011, 10:05:18 »
Yes, we don't know what camera he is using or even if it has an aperture or ND filter.

He should state all camera settings and confirm that no overrides are in use.

 

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