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Question about PowerShot SX100

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Offline pprovaz

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    Question about PowerShot SX100
    « on: 31 / January / 2017, 09:01:42 »
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    I am a newbie here, so sorry for my dumb questions ;)

    I want to develop a photobooth/time lapse application with PowerShot SX100, controled over USB with gphoto2 (running on Raspberry), so the time lapse photos will be transferred automatically over WiFi or LAN network to some server.

    I have to use an apperture priority mode. But in this mode the exposure control gives exposure times up to 1 second only (but in manual mode it is able to take 15 second photos). That is unusable at night.

    Can this CHDK help me to raise the maximum time in aperture mode when the camera is controled over USB? If so - how to be sure it will be automatically re-activated after powerdown? The camera would be on some locked place, so the physical access will be very limited.

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    Question 2

    Some newer Canon PowerShots do not support the remote capture at all (for example PowerShot A800). Is there any hack for those cameras to support remote capturing (capture control over USB)?
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    Offline srsa_4c

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    Re: Question about PowerShot SX100
    « Reply #1 on: 31 / January / 2017, 10:58:33 »
    I can only give a partial answer, I hope that others can fill in the missing pieces.
    Quote from: pprovaz on 31 / January / 2017, 09:01:42
    Can this CHDK help me to raise the maximum time in aperture mode when the camera is controled over USB?
    When using
    either
    - remote capture (the official Canon one)
    or
    - an auto-exposure mode (such as Av) with CHDK
    the answer is no. You can, however, switch to M mode when pictures become underexposed.
    When using the CHDK PTP interface, scripting can be used to set the desired exposure parameters (correct exposure has to be calculated in the script).
    Quote
    If so - how to be sure it will be automatically re-activated after powerdown? The camera would be on some locked place, so the physical access will be very limited.
    CHDK will load when using the bootable card method. Starting the camera is another story:
    - you can physically push the ON/OFF button
      - permanently, then controlling the camera's power supply
      - using a servo
    - you can solder wires to the button and control it from outside

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    Some newer Canon PowerShots do not support the remote capture at all (for example PowerShot A800). Is there any hack for those cameras to support remote capturing (capture control over USB)?
    Yes, using the CHDK PTP interface. For a start, see http://chdk.wikia.com/wiki/PTP_Extension .
    Note that AFAIK current gphoto also supports remote shooting on cameras that run CHDK (can't give details due to zero experience).
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    Offline pprovaz

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    Re: Question about PowerShot SX100
    « Reply #2 on: 31 / January / 2017, 13:22:30 »
    I thought there is some option in CHDK to break the maximum time limit, that can be used for shooting. So it is not usable in aperture prio mode?

    Sure, switching to full manual is an option. But the whole thing should be controlled automatically, without user input, so I have no idea, how to check in some program, if the shot is exposed correctly or not (and setup correct aperture and time). Truth is, that the best exposed shot should have maximal filesize (because it retains maximum detail, so no overburns and underexposed areas). So as an emergency solution I can program it to shot several times and check the filesizes, then pick the one with the maximum file size. No other ideas here :) This is why I've planned to use aperture prio mode to simplify the process and let the camera expose itself.

    I've planned to use 2 relays - one for camera power and second for the power button. Do you think it will work with the power button pressed permanently? That would save one relay.

    CHDK PTP interface - I will test that on my A800, thanks for the info :)
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    Offline waterwingz

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    Re: Question about PowerShot SX100
    « Reply #3 on: 31 / January / 2017, 14:04:16 »
    Quote from: pprovaz on 31 / January / 2017, 13:22:30
    I thought there is some option in CHDK to break the maximum time limit, that can be used for shooting. So it is not usable in aperture prio mode?
    The ability to go past the limit happens when CHDK manually sets the shutter speed.  The Canon firmware does not know that has happened and will not use the value in its calculations.

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    Sure, switching to full manual is an option. But the whole thing should be controlled automatically, without user input, so I have no idea, how to check in some program, if the shot is exposed correctly or not (and setup correct aperture and time).
    You can let a script handle all that for you.

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    I've planned to use 2 relays - one for camera power and second for the power button. Do you think it will work with the power button pressed permanently? That would save one relay.
    It should - you can experiment with this easily with your finger holding down the button.

    One advantage of the two relay design is that the power button signals the camera to shutoff in an orderly fashion. This might prevent some SD card corruption.
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    Offline srsa_4c

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    Re: Question about PowerShot SX100
    « Reply #4 on: 31 / January / 2017, 20:26:17 »
    Quote from: waterwingz on 31 / January / 2017, 14:04:16
    One advantage of the two relay design is that the power button signals the camera to shutoff in an orderly fashion.
    If power is controlled by the Raspberry board, the camera can be shut down cleanly with a script command (a button event) before power is turned off: https://chdk.setepontos.com/index.php?topic=12665.0
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    Offline pprovaz

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    Re: Question about PowerShot SX100
    « Reply #5 on: 01 / February / 2017, 02:08:59 »
    Thanks for the link. I see you mentioned SX100 power consumption there. Do you have some measurements in various situations?
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    Offline srsa_4c

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    Re: Question about PowerShot SX100
    « Reply #6 on: 01 / February / 2017, 20:45:43 »
    Quote from: pprovaz on 01 / February / 2017, 02:08:59
    Thanks for the link. I see you mentioned SX100 power consumption there.
    I don't think I posted in that thread. I may have posted some approximate current measurements (elsewhere) one or two times, but those were inaccurate - I don't have the equipment to make exact/long term power consumption graphs.
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