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Using a CHDK camera to trigger a DSLR.

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Offline vostok

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Using a CHDK camera to trigger a DSLR.
« on: 23 / August / 2008, 12:47:28 »
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Hi again,

what means of controlling the camera's USB-port does chdk have? What is needed to create a simple short-circuit in the usb-cable (a short circuit is needed for remote release of a dslr)?

Is a short circuit possible with just scripting, or will I have to send a some kind of a signal to the cable and then use something like a transistor switch to achieve a short circuit?
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Offline fudgey

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Re: Using a CHDK camera to trigger a DSLR.
« Reply #1 on: 23 / August / 2008, 13:40:46 »
Quote from: vostok on 23 / August / 2008, 12:47:28
what means of controlling the camera's USB-port does chdk have? What is needed to create a simple short-circuit in the usb-cable (a short circuit is needed for remote release of a dslr)?

Is a short circuit possible with just scripting, or will I have to send a some kind of a signal to the cable and then use something like a transistor switch to achieve a short circuit?

Currently none whatsoever, not in a script or in any other way. There is only a "cable detect" input which we use for the remote.

Someone once told me (search the forums and you may find it) someone once experimented and found (for his specific camera model) a way to control the USB mode pullup resistor. This method was unstable in some conditions (would crash the camera sometimes) and afaik has not been investigated further. But by switching the pullup, one could cook up a simple circuit to interface to your DSLR trigger in one of a zillion different ways.

The LEDs could be used for output from scripts, though, and you could interface a phototransistor to one of them.


edit: the pullup discussion was here, btw: http://chdk.setepontos.com/index.php/topic,547.msg9944.html#msg9944
« Last Edit: 23 / August / 2008, 13:45:49 by fudgey »
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Offline fe50

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Re: Using a CHDK camera to trigger a DSLR.
« Reply #2 on: 23 / August / 2008, 14:16:30 »
Playing sounds (in a script) is also a possible "output"...
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Offline vostok

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Re: Using a CHDK camera to trigger a DSLR.
« Reply #3 on: 23 / August / 2008, 14:21:04 »
Is there a simple way to flash ie. the AF-assist beam with some ubasic command? Do you suppose a simple phototransistor from an old ball mouse would do the job with only taping it to the lamp and connecting the two wires to my cable release?
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Offline whoever

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Re: Using a CHDK camera to trigger a DSLR.
« Reply #4 on: 23 / August / 2008, 14:46:29 »
UBASIC/TutorialScratchpad - CHDK Wiki

Aslo see led_tst.bas from the trunk (note that the functioning of set_led ubasic command depends on whether the one who ported to your cam really cared)
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Offline fe50

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Re: Using a CHDK camera to trigger a DSLR.
« Reply #5 on: 24 / August / 2008, 05:16:42 »
Quote from: vostok on 23 / August / 2008, 14:21:04
Is there a simple way to flash ie. the AF-assist beam with some ubasic command? Do you suppose a simple phototransistor from an old ball mouse would do the job with only taping it to the lamp and connecting the two wires to my cable release?

Yes, should work - disable the AF beam in the canon menu ("AF-assist Beam" = Off)...but you can't use timer modes, the AF beam blinks in this mode although it is disabled...an alternative could be the very bright blue print LED, it's not used by Canon while taking photos, CHDK blinks it only on boot and while saving a RAW file.

For scripting these are the LEDS:
LED_GREEN       4
LED_YELLOW      5
LED_ORANGE      7
LED_BLUE        8
LED_AF_BEAM     9
LED_TIMER       10

Use it with the LED number above, 1 for ON, 0 for OFF, like the following...
Code: (sdlbasic) [Select]
set_led 9 1
  sleep 2000
set_led 9 0
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Offline benedict

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Re: Using a CHDK camera to trigger a DSLR.
« Reply #6 on: 08 / April / 2009, 18:11:48 »
It's a little confusing from reading the various Wiki and Forum entries on LED control whether this is available on all cameras yet.

I'm trying this on an A650IS, but I haven't been able to get any kind of LED control working yet.  Am I simply trying this on a camera that doesn't currently support LED control?  Or am I doing something wrong?

I've tried this in UBASIC and LUA both, basically using the same code posted above to set an LED to 1, sleep, then set it to off.

Thanks,

Tom
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databoy

Re: Using a CHDK camera to trigger a DSLR.
« Reply #7 on: 08 / April / 2009, 22:28:07 »
As I understand the post; you are trying to use a CHDK enabled camera to trigger a DSLR. ie The DSLR is always a slave device. If that is the case your best and simplest way is to use a VOX (voice operated relay) coupled to the camera speaker. I have tried the circuit to control external devices triggered by an S3IS and works reliably every time. (I have yet to experienced any problems with false triggering)

You can set the unit to operate with a pre-trigger. ie half press of the shutter. Ideal for switching on external lighting.

The most popular kit on the net is from Jaycar in Australia. In the USA: http://www.electronickits.com/kit/complete/elec/k126.htm

K126.pdf is the actual circuit. The layout is not critical, you can veroboard it, if you cannot purchase the kit in your area.

Due to the high frequency of the camera speaker; you will need to make an L bracket and mount the front of the microphone to the front of the camera speaker.

I am also using the device to trigger the timing sequence to PAN a camera and automatically shoot a sequence of shots.
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Offline KGyST

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Re: Using a CHDK camera to trigger a DSLR.
« Reply #8 on: 29 / October / 2010, 15:47:06 »
It's sad to hear that this feature cannot be done easily, I've been thinking about shooting lightnings with a more serious camera than my current PowerShoot A550, but I won't buy a dedicated camera for this purpose only.
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