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Understanding Interval Time
#1
Hi, I am constantly getting an exclamation point on my interval time display when I start a timelapse. I am trying to understand everything that compose this time at each loop and I made this image below. Assuming camera is in Bulb mode, can you see if I made it correctly?

[Image: KxCgIX1.jpg]

Is there any time missing? Is there any overlaps between each step? Even though I am taking into account all of these times, I still can't reach anywhere near minimum interval time. Sometimes I cannot increase my motor post delay setting higher than 1 second. I have used already 2 seconds (it is good to wait dumping vibrations).

Airic, is there a possibility to set auto minimum interval time according to our settings and let the total rec time as a consequence?

Thanks!
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#2
Hello there,
yes your picture summarises it pretty much. Here is my version on how it basically works:


The interval time is the target time that defines when to start a new cycle. The exclamation mark indicates that your target time was too short and the real cycle time could not be met. Motor moves have different lengths (e.g. acceleration phase vs max speed phase). The reason why this is not implemented yet is that after every setup change, one would need to simulate the complete move to determine the longest move time needed. I might implement that in a later version though. 


As a solution to the problem, I generally suggest to NOT set your camera to BULB mode. Even though the trigger signal (length) is pretty accurate, it seems that cameras have a hard time to trigger as accurate as the signal they receive. For example do certain cameras not even register a trigger signal under 100ms (which is a very long time for electronics!). This fuzzy behaviour will lead to unprecise trigger behaviour which will as a result cause that your exposures will not have the same length and thus you will have brightness flicker in your final time-lapse. I do recommend setting the exposure in your camera only (MANUAL). If you use the camera built in functionality you will get much, much higher precision because you eliminate an additional factor in the system. I assume that the camera knows best how to follow the set exposure time exactly. Use the trigger signal (e.g. 100ms) only to trigger the camera and let the camera do the rest. The camera post delay should then be slightly longer than the actual set exposure time to factor out any inaccuracy caused by the communication with the camera. for example:


You use 500ms focus time (to wake up the camera or to focus? I recommend using manual focus all the time!)
Camera exposure time (100ms to just trigger the camera; the camera is set to manual and exposes 2 seconds)
Camera post delay of at least 2200ms camera post delay (this is the time the system waits until the camera is done exposing)


I guess that you get the error because your real motor moves are tool long than the time you have available in your cycle:


slot time for motor moves = cycle_time - camera_focus - camera_trigger - camera_post - motor_post


Continuous mode might be a solution here. I do prefer this mode as it gives a lot smoother looking time-lapses and you can basically expose all the time through your time-lapse (no motor move phase, no motor post). Give it a try Wink


I hope that helped!
Cheers!
 
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