Drivelapse script - page 3 - Completed and Working Scripts - CHDK Forum

Drivelapse script

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Offline reyalp

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Re: Drivelapse script
« Reply #20 on: 29 / August / 2012, 13:26:13 »
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I'm concerned that adding a second half shoot will almost certainly slow things down beyond 1 second.
It's a little bit slower for sure. It also leaves you with some delay between the metering and actual shot, so there is still potential for bad exposure in fast changing lighting conditions.
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Do you recall whether it's possible to skip the second half shoot and just do half shoot > set_* > release > shoot/full shoot ?
The cameras treat "quick" shots (not waiting for everything to be ready at half press) differently. It may work, but may be dependent on the camera and camera mode.
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If not, I will look into doing this using prop cases, but I think this might reduce the number of camera models the script will work with.
In Lua, you can use propcases by name, as shown in lapsers post. In ubasic, things would get more complicated, although if you are only setting the Tv and Sv, it would don't be too bad check the propset at the start and put appropriate hard-coded propcase numbers in variables.

Note that currently, only propset4 has TV2, so that would be an additional special case if you want to use it.
Don't forget what the H stands for.

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Offline lapser

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Re: Drivelapse script
« Reply #21 on: 29 / August / 2012, 20:45:31 »
Note that currently, only propset4 has TV2, so that would be an additional special case if you want to use it.
Thanks for that info. I added tests for nil values. Do all cameras have a TV value at least?
EOS-M3_120f / SX50_100b / SX260_101a / G1X_100g / D20_100b
https://www.youtube.com/user/DrLapser/videos

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Offline reyalp

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Re: Drivelapse script
« Reply #22 on: 29 / August / 2012, 22:08:34 »
Thanks for that info. I added tests for nil values. Do all cameras have a TV value at least?
Yes, TV is required for CHDK to work at all. TV2 is an extra.
Don't forget what the H stands for.

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Offline gjb

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    • Motoscape Rally 2012 - Team Grayson
Re: Drivelapse script
« Reply #23 on: 30 / August / 2012, 04:43:02 »
Thanks for that info. I added tests for nil values. Do all cameras have a TV value at least?
Yes, TV is required for CHDK to work at all. TV2 is an extra.

For cameras that don't have TV2, is it possible to update the EXIF data to display the correct value?

Certain timelapse software relies on the EXIF data being correct to calculate smoothing between frames etc.


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Offline lapser

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Re: Drivelapse script
« Reply #24 on: 30 / August / 2012, 12:37:06 »
For cameras that don't have TV2, is it possible to update the EXIF data to display the correct value?
Certain timelapse software relies on the EXIF data being correct to calculate smoothing between frames etc.
The EXIF data isn't exact enough to use, since it's truncated to the nearest 1/3 ev by the camera. The camera only can change exposure by 1/3 ev, which is visible in a time lapse. CHDK can change exposure by 1/96 ev, which is not noticeable, so you don't need to "de-flicker" the time lapse photos with other software. It's one of the main reasons to use CHDK for time lapse.

I've attached a test video of a sunset that shows how steady the brightness is with CHDK. Tv starts at 1/100 sec and ends at 60 seconds (dark frame off). I'm using the propcase method of setting TV immediately after metering.
EOS-M3_120f / SX50_100b / SX260_101a / G1X_100g / D20_100b
https://www.youtube.com/user/DrLapser/videos

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Offline reyalp

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Re: Drivelapse script
« Reply #25 on: 30 / August / 2012, 16:07:00 »
For cameras that don't have TV2, is it possible to update the EXIF data to display the correct value?
Some do already, without TV2. For others, there's a good chance there is an equivalent to TV2 that just needs to be found. In the propcase viewer, look for another propcase that gets set to the TV value chosen by the canon firmware.

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The EXIF data isn't exact enough to use, since it's truncated to the nearest 1/3 ev by the camera. The camera only can change exposure by 1/3 ev, which is visible in a time lapse.
The canon "maker note" in exif may have more accurate values (see http://www.exiv2.org/tags-canon.html ). Also may have the correct value when regular exif is not updated.
Don't forget what the H stands for.

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Offline gjb

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Re: Drivelapse script
« Reply #26 on: 31 / August / 2012, 17:28:56 »
I've modified my own copy of the script to use set_prop 69 T rather than set_tv96_direct T. This works for my camera, but I'll work on implementing this in a model-independent way when I get back.

The rally starts tomorrow!

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Offline lapser

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Re: Drivelapse script
« Reply #27 on: 31 / August / 2012, 18:47:58 »
I've modified my own copy of the script to use set_prop 69 T rather than set_tv96_direct T. This works for my camera, but I'll work on implementing this in a model-independent way when I get back.
The rally starts tomorrow!
Good luck with the rally, and I hope you post a video link here when you're done. I think we may have figured out the optimum way to meter and shoot a picture with CHDK.

I have another question for the gurus. If you modify a @param in a script, is there a way to make sure the new value is saved?

Code: (lua) [Select]
@param p = Log File Name
@default p 0

p=p+1 -- trying to write a new log file every time the script is run
print_screen(p)
print(os.date())
EOS-M3_120f / SX50_100b / SX260_101a / G1X_100g / D20_100b
https://www.youtube.com/user/DrLapser/videos


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Offline reyalp

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Re: Drivelapse script
« Reply #28 on: 01 / September / 2012, 00:53:32 »
I have another question for the gurus. If you modify a @param in a script, is there a way to make sure the new value is saved?
There is no such feature, script params just supply the default value, they aren't persistent variables for script. Technically you could use Lua file IO to fiddle with the files in CHDK/DATA but it's probably not a good idea. Given that Lua does have full file IO capability, you could also make your own logging scheme.

I'd suggest starting a new thread if you have other questions like this, since it not really related to gjb's script.
Don't forget what the H stands for.

Re: Drivelapse script
« Reply #29 on: 16 / November / 2012, 08:44:27 »
Hi ! Thanks for creating such a great script~

My camera is IXUS 850 and I have followed all the instructions,

all default values,  set the Interval as 1 second.



I run the script for two times,  indoor with medium lighting.

Both times turned out the scripts took photos roughly every 3 seconds.


I checked the EXIF, the Shutter is 1/40 sec and Aperature is F 2.8.


Could anyone help? Many thanks~!


 

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