April 12, 2009 by shutterdrone
Posted in
Camera Control
The time-lapse engine provides the following camera control functions:
- Exposure Time
- Interval (Cycle Delay)
- Post-Exposure Delay Time
- Pre-focus Tap Time
- Focus High with Shutter
- Maximum Shot Count
- Camera Repeat Cycle
Exposure and Interval timers are non-blocking, this means that you may continue to interact with the engine while a timer is engaged (e.g. during an exposure), or even trigger keyframes. This is especially useful when you want to continue to modify your program based on time during the execution of your program. Post-exposure and Pre-focus tap timers are blocking, however, and you may not expect time-based keyframes to execute during these actions.
Exposure Time
Exposure time is set in milli-seconds, from 1 to 4,294,967,296. Or, 1/1000th of a second to nearly 50 days. (49.7103 days to be more precise!)
- For bulb-mode exposures, you should set the exact amount of exposure time
- For camera-set exposure values, set the minimum trigger time required by your camera for reliable shooting
You will need to perform some experimentation to determine what the minimum trigger time for your camera is. Some cameras will detect a trigger on the remote in 10-20 mS, while others may require 70 or even 100mS to detect the remote accurately. Make sure you let your camera run for a while with a single trigger time when testing to make sure that it doesn't miss the occasional trigger. The fastest time that your camera will reliably recognize is the preferred trigger time to use for all camera modes except 'bulb'.
The Exposure timer is non-blocking.
Interval (Cycle Delay)
Interval is set in seconds, from 1 to 65,536 (Around 45.5 days.)
The interval time is the amount of time to wait between shots.
The Interval timer is non-blocking.
Post-Exposure Delay Time
Post-exposure delay time is set in milli-seconds, from 1 to 65,536. (65.5 seconds.)
The post-exposure delay timer specifies how long after completing a shot to wait before moving any motor. This is used when the Exposure Time Setting is less than the actual exposure value set in the camera. For example, when shooting with the camera in manual mode, if the camera is set to a 1 second exposure, and the Exposure Time Setting is set as 70mS, you would want a post-exposure delay of at least 930mS to prevent the motors from moving while the camera is exposing.
Note: If your combination of exposure time, post-exposure time, and the amount of time it takes to move your motors the required distance exceeds your interval time, the actual interval time between shots will be greater than or equal to the combination of these times. The engine will not execute another shot until all outstanding activities have been completed for the current cycle. It will, however, attempt to execute the next shot at the earliest available opportunity.
The post-exposure delay timer is a blocking timer, and therefore no time-based keyframes will occur while this is running, and the engine will not act upon any serial commands while in post-exposure delay.
Pre-Focus Tap Time
Pre-Focus tap time is set in milli-seconds, from 1 to 65,536. (65.5 seconds.)
The pre-focus tap timer allows you to tap the focus line (for cameras and remote setups that support this capability) immediately before a shot is executed (exposure is triggered). This is especially useful for longer interval times where the camera may go to sleep between shots, causing shot cycles to get missed.
The order of operations, when a positive pre-focus tap time is set, is as follows:
- Activate the focus line
- Delay tap time mS
- De-activate the focus line
- Delay tap time mS
- Trigger exposure (activate exposure line)
Thus, you will have a delay of at least 2x your pre-focus tap time. The cause for the second delay is to prevent certain cameras from ignoring an exposure trigger that comes too soon after the pre-focus tap.
The pre-focus tap timer is a blocking timer, and therefore no time-based keyframes will occur while this is running, and the engine will not act upon any serial commands while in focus is being executed.
Focus High with Shutter
For some cameras, especially certain Nikon cameras, the focus line must be engaged whenever the shutter line is triggered using a wired remote. This setting allows one to enable this behavior and control these cameras properly.
Maximum Shot Count
Maximum shot count is an integer from 1 to 65,536.
The camera, and camera alone, will be disabled when the maximum shot counter is reached within the current program execution. You may rather choose to disable the camera after a certain number of shots, and re-enable it after a certain amount of time through the use of actions and camera and time keyframes.
Setting the maximum shot count to zero specifies that there should be no maximum shot count, and the camera will fire until the program is stopped, paused, or an action to disable the camera is taken.
Camera Repeat Cycle
A Camera Repeat Cycle allows you to trigger multiple exposures at each interval, using actions in-between to script out complex behaviors. A typical use might be to easily create a gigapanoramic photo sequence by using repeat cycle for the rows, and the normal program execution for the vertical movement changes. One could also use it to shoot several interlaced videos at once, with different output speeds - or even a couple of interlaced videos at once with different subjects in the same visible area.
The Repeat Cycle options are a little more involved than can be discussed in a paragraph, so please see the documentation for this feature specifically.