Can a script blank the display? A590IS - Script Writing - CHDK Forum
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Can a script blank the display? A590IS

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Offline peabody

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Can a script blank the display? A590IS
« on: 21 / February / 2009, 23:04:23 »
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It would be beneficial to battery life if the LCD display could be turned off while a long-term intervalometer script is running.  Or if the DISP button could be enabled while the script is running so that one could manually turn the display off and on as needed.  Ending the script would then automatically turn the display back on.   Are there script commands that would permit this on an A590IS?

And while I'm asking, is there an intervalometer script for the A590IS that somebody here likes.

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Offline Microfunguy

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Re: Can a script blank the display? A590IS
« Reply #1 on: 22 / February / 2009, 05:13:13 »
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Offline fudgey

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Re: Can a script blank the display? A590IS
« Reply #2 on: 22 / February / 2009, 05:37:29 »
You can either have the script press the disp button (and check propcases to find out which state is active) or you can use the set_backlight command to disable LCD backlight (which makes up most of the display's current consumption but does not shut down the sensor like the display button does). Av plug can also be used to make the LCD shut down, but that won't shut down the sensor either and also acivates video output driver, causing higher current drain compared to set_backlight.

set_backlight has the downside that it must be called again after each shot, and that live view image must be given time to set its exposure before calling it again; otherwise backlight will just stay on.


In short you'll want to use the display button. I'm sure I've seen scripts doing just that, but can't remember which one AND keep in mind that different cams (A/ixus/S/G) all don't have the same kind of disp button usage, so a script for ixus may not work for you this way.

But can't you just turn off the display and then start the script? (sorry, I really haven't tried this).
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Offline reyalp

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Re: Can a script blank the display? A590IS
« Reply #3 on: 22 / February / 2009, 06:07:59 »
You can also set chdk to NOT override the auto display off function when a script is running. Then the screen will turn off after the normal timeout.
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Offline Microfunguy

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Re: Can a script blank the display? A590IS
« Reply #4 on: 22 / February / 2009, 06:46:01 »
Quote from: reyalp on 22 / February / 2009, 06:07:59
set_backlight has the downside that it must be called again after each shot

In the SDM time_lapse.bas script that is done automatically.

Quote
In short you'll want to use the display button. I'm sure I've seen scripts doing just that, but can't remember which one

On this page http://stereo.jpn.org/eng/sdm/ubasic.htm is the command 'lcd_on-off' that uses the DISPLAY buttons to turn LCD on/off.
Does not work on all cameras.

There is also 'turn_backlight_on' and 'turn_backlight_off' that does work on all cameras.

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Offline PhyrePhoX

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Re: Can a script blank the display? A590IS
« Reply #5 on: 22 / February / 2009, 07:15:40 »
sounds to me like a broken record that is continuing to skip.
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Offline peabody

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Re: Can a script blank the display? A590IS
« Reply #6 on: 22 / February / 2009, 12:19:05 »
On my A590IS, going into CHDK ALT mode disables the DISP button.  And if I run the Default Script, DISP remains disabled.   So I suppose there's a possibility that having the script push that button would similarly have no effect.

I've tried turning off the display with the button, and then going into ALT mode, and the button remains disabled.  Of course I can't really tell I'm actually in ALT mode since the display is dark.  But if everything is still working, I think I could still do the intervalometer with the display off, if only I could find a way to load the right script in the dark.  Well, maybe just rename it to be the "default" script?

But it would be better to have manual control of the DISP button while the script is running.  That way you could have the display on when you start the script, then turn it off by hitting the DISP button manually, but then come back every now and then to turn it on and see how things are going.  Is it just not possible in the A590 to retain the DISP button's functionality while in ALT mode, or is that just a programming decision somebody made?
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Offline peabody

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Re: Can a script blank the display? A590IS
« Reply #7 on: 22 / February / 2009, 12:36:31 »
Quote from: fudgey on 22 / February / 2009, 05:37:29
set_backlight has the downside that it must be called again after each shot, and that live view image must be given time to set its exposure before calling it again; otherwise backlight will just stay on.

I'm confused.   With the A590, if I turn off the display with the DISP button, the display remains off between shots - so long as I have Review turned off.  The display doesn't appear to be involved in setting the exposure.  Can you refer me to something that explains how the display might be involved in setting the exposure?  I've seen references to the "sensor" in the display, as opposed to the backlight.  Is this all explained somewhere?
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Offline fudgey

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Re: Can a script blank the display? A590IS
« Reply #8 on: 22 / February / 2009, 14:08:42 »
Quote from: peabody on 22 / February / 2009, 12:19:05
I've tried turning off the display with the button, and then going into ALT mode, and the button remains disabled.  Of course I can't really tell I'm actually in ALT mode since the display is dark.  But if everything is still working, I think I could still do the intervalometer with the display off, if only I could find a way to load the right script in the dark.  Well, maybe just rename it to be the "default" script?

So everything works perfectly. You just start the camera, load up and set the script parameters to your liking, exit alt mode, press disp, press alt and shoot. Wait a little while to see that the camera actually shoots and go away, knowing the script works. If still in doubt, do a test run with display enabled and then restart with display off.

Quote from: peabody on 22 / February / 2009, 12:19:05
Is it just not possible in the A590 to retain the DISP button's functionality while in ALT mode, or is that just a programming decision somebody made?

The disp button works perfectly well during script run, but it's the script that must press it, because the script takes control over the keyboard so that you can reprogram them in the script for other functions. You need to add a command to press the disp button in the script if you want that to be done by the script. This is a very simple addition:

in uBASIC: click "display"
in Lua: click("display")

If you need to press it more than once to shut the display down, insert sleep 500 (uBASIC) or sleep(500) (Lua) between consecutive clicks.
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Offline fudgey

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Re: Can a script blank the display? A590IS
« Reply #9 on: 22 / February / 2009, 14:13:25 »
Quote from: peabody on 22 / February / 2009, 12:36:31
I'm confused.   With the A590, if I turn off the display with the DISP button, the display remains off between shots - so long as I have Review turned off.  The display doesn't appear to be involved in setting the exposure.  Can you refer me to something that explains how the display might be involved in setting the exposure?  I've seen references to the "sensor" in the display, as opposed to the backlight.  Is this all explained somewhere?

Disp button turns off the LCD and it turns off the sensor.
set_backlight only turns off the LCD backlight, not the LCD or the sensor.

There's a BBBBBBBBBBBIIIIIIIIIIIGGGGG difference between these two. After the camera has shot, it returns to live view if LCD is  or AV out is enabled (whether or not its all lit up or not). And to show a live view image, it has to make up its mind about how bright an image to show (what sort of aperture and ISO to use during live view). It takes a little while to adapt, especially if its very dark.

This has next to nothing to do how your photos turn out, and absolutely nothing to do with anything if your LCD is disabled usinb the display button. It just effects how set_backlight has to be used, because the camera resets backlight back on when it finishes adjusting the LCD after a shot if the LCD happens to be enabled.
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