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TV mode and setting exposure time

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TV mode and setting exposure time
« on: 17 / July / 2013, 13:37:09 »
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I want to use my a4000 to take long exposures through a telescope, EDIT: (via a USB connection, without changing zoom). I've read a fair amount of the scripting manuals on the CHDK site, but I don't seem to be able to override the settings from the CHDK overrides menu. In Lua, the statement:

set_tv96_direct9(val)

does not seem to control the shutter speed/exposure.

Help?
« Last Edit: 17 / July / 2013, 16:22:13 by Saethlin »

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Offline msl

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Re: TV mode and setting exposure time
« Reply #1 on: 17 / July / 2013, 15:16:42 »
You do not need a script for long exposures. Use the Tv override functions.

CHDK version 1.1: http://chdk.wikia.com/wiki/CHDK_User_Manual#Override_shutter_speed
CHDK version 1.2: http://chdk.wikia.com/wiki/CHDK_1.2.0_User_Manual#Override_Tv

Adjust the the exposure time in CHDK menu and make a photo.

A script is similar:
Code: [Select]
set_tv96_direct(-480)
shoot()
The value -480 stands for an exposure time of 32 seconds.

msl
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Re: TV mode and setting exposure time
« Reply #2 on: 17 / July / 2013, 16:19:44 »
Oops, sorry. Initial post was incomplete.

I want to take long exposures at a user-defined exposure time, from a USB connection, without changing zoom. Can that be done without a script?
« Last Edit: 17 / July / 2013, 16:22:24 by Saethlin »

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Offline reyalp

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Re: TV mode and setting exposure time
« Reply #3 on: 17 / July / 2013, 16:57:31 »
Oops, sorry. Initial post was incomplete.

I want to take long exposures at a user-defined exposure time, from a USB connection, without changing zoom. Can that be done without a script?
It will ultimately use a script if you are doing it with a PTP client over USB. (edit: although if you set the override in the menu, shooting over ptp should honor that override setting)

in the chdkptp client, you should be able to do
shoot -tv=30

This will use set_tv96_direct under the hood, so if that actually doesn't work you would still have a problem. However, set_tv96_direct should work. You need to call it outside of half shoot, and you need to give the value in APEX*96 units.

If the example script msl gave you doesn't result in a 30 sec exposure, there is a problem and we will probably need more details to diagnose it.
Don't forget what the H stands for.


Re: TV mode and setting exposure time
« Reply #4 on: 01 / August / 2013, 14:19:41 »
I guess I don't know nearly enough about ptpcam, because when I execute chdk-ptp.cmd, I get the <conn> prompt, but the command

shoot -tv=30

returns:

unknown command

EDIT:
chdkptp.exe seems to be working. I think I've got this  :D
« Last Edit: 01 / August / 2013, 14:28:39 by Saethlin »

 

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