3.3 Controlling exposure time with the SMC
The SMC motion controller is capable of doing bulb exposure control. The shutter line will be kept engaged for as long as
the exposure time parameter is configured for. The exposure time is entered in milliseconds, and may be set for as low as
your camera will recognize, or up to about 50 days (... not recommended, you might burn out your sensor)
Actions:
1. Set camera to bulb (B) mode
2. “ENTER” to enter the main menu
3. “DOWN” to select Camera and press “ENTER”
4. “DOWN” to select Exp. Time and press “ENTER”
5. “UP” or “DOWN” to alter the value
6. “ENTER” to save or “RIGHT” to abort
7. “DOWN” to select Exp. Delay and press “ENTER”
8. “UP” or “DOWN” to set the value to 0
9. “ENTER” to save or “RIGHT” to abort
3.4 Controlling exposure time on the camera
For most cases, you’ll find it best to control the exposure on the camera, using manual, or some other mode to dial in the
appropriate exposure time. Under certain conditions it will be important to tell the SMC the actual exposure time you’ve
dialed in on the camera, so that it does not attempt to trigger an exposure at the wrong time. The amount of time to wait
after triggering an exposure is configured via the exposure delay value. This value is input in milliseconds, so one second
would be entered as 1000.
To disable any delay after triggering an exposure, set the exposure delay value to zero.
For
continuous motion
control, it is generally not necessary to set an exact
exposure delay
in the SMC unless it exceeds
your configured interval time. However, for interleaved, or shoot-move-shoot, motion control, it is essential to dial in the
correct exposure time to prevent motor movement during the exposure. In many cases, it is advantageous to exceed the
actual exposure time configured on the camera in the exposure delay parameter.
Additionally, you should configure the exposure time to its minimal value to prevent unnecessary delays. Each camera
may have a different minimum exposure time required to honor the request to trip the shutter. For many cameras 200mS
is a safe bet.
Exposure time must always
be greater than zero
to trigger the camera.
Actions:
1. Set camera to manual (M) mode
2. Dial in the correct exposure on the camera
3. “ENTER” to enter the main menu
4. “DOWN” to select Camera and press “ENTER”
5. “DOWN” to select Exp. Time and press “ENTER”
6. “UP” or “DOWN” to set the value to the minimum time for your camera
7. “ENTER” to save or “RIGHT” to abort
8. “DOWN” to select Exp. Delay and press “ENTER”
9. “UP” or “DOWN” to set the value
10. “ENTER” to save or “RIGHT” to abort
Notes:
•
Remember that there are one thousand milliseconds in a second, so if you want a one second exposure, it would be
entered as 1000.
•
Different cameras have different exposure time requirements for bulb mode, both minimum and maximum time. If you need
a controlled exposure for a shorter period of time than your camera will allow in bulb mode, you must use the camera to
control the exposure in using its manual mode. You may need to experiment to discover the correct minimums and
maximums for your particular camera.
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