You can capture a long exposure using shutter speed settings up to 30 seconds, bulb mode or using a DSUSB device.
(shows ControlMyNikon, but functionality is the same in ControlMyCanon).
Example: Capturing a Long Exposure
Let’s capture a Light Frame, and a Dark Frame (used for noise reduction in third-party applications).
– Connect to the camera.
– Disable all noise reduction options in the body LCD menu.
– Go to the Workflow menu and select ‘Long Exposure’.
– Follow the instructions until step 12.
– The Capture button will be disabled if the body is not in Bulb mode. Set it to bulb mode by selecting ‘bulb’ in the shutter speed list.
– Click on the ‘Capture’ button.
– When the capture is complete, you have captured the ‘Light Frame’. This is the image without noise reduction.
– Optionally, do step 14 and 15 to capture a ‘Dark Frame’. This image is a picture of sensor noise only.
– The Light and Dark Frame images are stored in the current folder with the current filename settings.
– There will be no attempt to autofocus prior to each capture if you have set the body to not require focus before triggering the shutter. This is normally known as ‘Release Priority’.
– ControlMyCanon can capture the Dark Frame but cannot use it to remove noise from the Light Frame. Use another application for that, such as the excellent Raw Therapee (free).
– Keep the camera firmly mounted so that it cannot move.