Multiple cameras and long exposures problem

[Sacripante]

The problem of controlling long exposures of multiple cameras can be approached by controlling a loop that first opens all the shutters, and after a given amount of seconds, closes the shutters and stores the image files. To trigger almost simultaneous all the camera exposures, a python code can loop over the camera port addresses and send a 'Press Full’(or ‘Immediate’) to open each shutter.

In the sample code below, the shutter unexpectedly closes immediately after the ‘Press Full’ command sent to a set of Canon EOS 5D-Mark III cameras preset to Bulb. What can be done to prevent the shutter from closing without waiting for a Release Full command from a second loop?

def _do_expose(self, addr): 
    # # Select camera
    port_info_list = gp.PortInfoList()
    port_info_list.load()
    self.idx    = port_info_list.lookup_path(addr) 
    self.config   = self.camera.get_config()
    # # Camera selected
    self._status = 'Exposing'
    self._bulb = self.config.get_child_by_name('eosremoterelease')
    self._bulb.set_value('Immediate') 
    self.camera.set_config(self.config) 
    self._start_time = astropy.time.Time.now()
    return self._status

[jim-easterbrook]

I've no idea. I've never tried to do anything like this.

[jim-easterbrook]

One thought - you are selecting your camera in the _do_expose method, but I'd expect that to be done in the class __init__. You need one object per camera which will keep a reference to that camera. If the camera goes out of scope I would expect the exposure to end.

[Sacripante]

You are making an excellent point. I totally agree with you. What if I define an array that keeps reference of each camera, port number and state. This way the code not only can monitor if a camera goes out of scope but also can be easily adjusted in the case of cameras of different types.

…

On Fri, Nov 4, 2022 at 3:49 AM Jim Easterbrook ***@***.***> wrote: One thought - you are selecting your camera in the _do_expose method, but I'd expect that to be done in the class __init__. You need one object per camera which will keep a reference to that camera. If the camera goes out of scope I would expect the exposure to end. — Reply to this email directly, view it on GitHub <#146 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AD5BKNU6EMQUMW3OHWDRJJ3WGS5ZBANCNFSM6AAAAAARWOVGR4> . You are receiving this because you authored the thread.Message ID: <jim-easterbrook/python-gphoto2/repo-discussions/146/comments/4054294@ github.com>

-- Dr. Alex Coletti <http://www.linkedin.com/pub/alex-coletti/b/6bb/535> Mobile: (301) 920-6669 Linkedin <http://www.linkedin.com/pub/alex-coletti/b/6bb/535>

[jim-easterbrook]

Whatever you're comfortable with. I would use a more object oriented approach, defining a class to represent a camera, with methods such as start_exposure and stop_exposure. Then have a list of instances of that class. You could also have derived classes for different camera types. I don't think you need to hang on to the port number once you've connected to the camera though.

for c in camera_list:
    c.start_exposure()
time.sleep(30)
for c in camera_list:
    c.stop_exposure()

[Sacripante]

Thanks! I like it more pythonic! I made a similar code that I tested on one single camera and works fine (the shutter stays open). The only difference is in the portion that searches for the camera

…

On Fri, Nov 4, 2022 at 6:09 AM Jim Easterbrook ***@***.***> wrote: Whatever you're comfortable with. I would use a more object oriented approach, defining a class to represent a camera, with methods such as start_exposure and stop_exposure. Then have an array of instances of that class. You could also have derived classes for different camera types. I don't think you need to hang on to the port number once you've connected to the camera though. for c in camera_list: c.start_exposure() time.sleep(30) for c in camera_list: c.stop_exposure() — Reply to this email directly, view it on GitHub <#146 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AD5BKNS6JHFF5X6KT7RPDUDWGTOGLANCNFSM6AAAAAARWOVGR4> . You are receiving this because you authored the thread.Message ID: <jim-easterbrook/python-gphoto2/repo-discussions/146/comments/4055402@ github.com>

-- Dr. Alex Coletti <http://www.linkedin.com/pub/alex-coletti/b/6bb/535> Mobile: (301) 920-6669 Linkedin <http://www.linkedin.com/pub/alex-coletti/b/6bb/535>

[Sacripante]

One more question though. Without a usb/port number, how can 'c' find the right camera for the start_exposure and stop_exposure methods? Are you thinking of adding in each method a search for the serial number?

…

On Fri, Nov 4, 2022 at 6:09 AM Jim Easterbrook ***@***.***> wrote: Whatever you're comfortable with. I would use a more object oriented approach, defining a class to represent a camera, with methods such as start_exposure and stop_exposure. Then have an array of instances of that class. You could also have derived classes for different camera types. I don't think you need to hang on to the port number once you've connected to the camera though. for c in camera_list: c.start_exposure() time.sleep(30) for c in camera_list: c.stop_exposure() — Reply to this email directly, view it on GitHub <#146 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AD5BKNS6JHFF5X6KT7RPDUDWGTOGLANCNFSM6AAAAAARWOVGR4> . You are receiving this because you authored the thread.Message ID: <jim-easterbrook/python-gphoto2/repo-discussions/146/comments/4055402@ github.com>

-- Dr. Alex Coletti <http://www.linkedin.com/pub/alex-coletti/b/6bb/535> Mobile: (301) 920-6669 Linkedin <http://www.linkedin.com/pub/alex-coletti/b/6bb/535>

[jim-easterbrook]

It finds the camera when you create an instance of your class. Then keeps a reference to the python-gphoto2 Camera object which is used for all subsequent interactions.

[Sacripante]

Wow! Thanks

…

On Fri, Nov 4, 2022 at 9:57 AM Jim Easterbrook ***@***.***> wrote: It finds the camera when you create an instance of your class. Then keeps a reference to the python-gphoto2 Camera object which is used for all subsequent interactions. — Reply to this email directly, view it on GitHub <#146 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AD5BKNUTDTHX4LBQXYBOG3DWGUI47ANCNFSM6AAAAAARWOVGR4> . You are receiving this because you authored the thread.Message ID: <jim-easterbrook/python-gphoto2/repo-discussions/146/comments/4057147@ github.com>

-- Dr. Alex Coletti <http://www.linkedin.com/pub/alex-coletti/b/6bb/535> Mobile: (301) 920-6669 Linkedin <http://www.linkedin.com/pub/alex-coletti/b/6bb/535>

[Sacripante]

Thank you. The method you suggested worked like a charm