Mastering Long Exposure Time-lapse With the MX2

One of the most interesting and popular uses of the Stage Zero system is night time-lapse.  It is also one of the most challenging, making it important to have a complete understanding of Intervals and the MX2 Interleave Cycle. It’s a good idea to practice both night timelapse (without motion) and day-time motion timelapse (without long exposures) before trying to combine the two. A typical time-lapse shot during the day, often has lots of “empty exposure” time. That is, the camera is simply sitting unexposed waiting to be triggered for a short exposure. During a night time-lapse segment, the camera is often exposing for greater percentage of the overall interval time.

Interval Example: If your target is a 25 second exposure, you would set your interval time close to 25 seconds adding 2-3 seconds (for save to card buffer) = 27-28 second overall interval. A typical timelapse sequence is 300 shots so on a 27-28 second interval total run time would be 135-140 minutes.

For some great general astrophotography advice, a good place to start is Ben Canales “Landscape Astrophotography Tutorial – First Night Out”

Settings on the MX2 Controller

When your shooting long exposure time-lapse it’s desirable to have the system set to Interleave mode which is commonly referred to as ‘move-shoot-move’.  This mode can be thought of as an alternating cycle between the motor moving to the next position and the camera’s shutter being triggered. To master this cycle it’s important to understand how it actually breaks down into smaller events. Let’s check out the finer points of using the MX2 Controller for long exposure timelapse using Interleave mode.

Shoot-Move-Shoot with the MX2

Start by setting the following on the MX2:

Settings>Motor Sl Mod>Interleave [enter]

Axis 1>Fixed SMS>ON [enter]

This combination of settings creates a situation where the motor will move a set distance between shots no matter what the interval. It’s important to understand, with these settings enabled the motor 1 area on the main screen is now displaying distance per shot. So for example if we set it to 0.20i that denotes .2 inches per shot.

Understanding the Interleave Cycle

To further understand how to work with long exposures it’s important to understand how the cycle breaks down into smaller parts. Here are the sequence of events that occur and furthermore add-up to the minimum interval time.:

1. Focus Tap Time

2. Exposure Time

3. Exposure Delay Time

4. The Motor moves

5. [Repeat]

Each of these events have a corresponding setting in the Camera section of the MX2 main menu.  It’s important to note each one of these settings add up! So if you find that the MX2 is not allowing you to set an interval below a certain time this means one or all of these settings are adding up to that minimum interval allowed.  Let’s break down each of these settings and investigate the opportunities:

Camera>Focus Tap ms> : this is the amount of time the focus signal is sent to the camera body in milliseconds. You can think of this setting as having two functions, the first is the more intuitive function which is to wake the camera and execute a focus lock based on the focus drive setting. The ‘wake up’ command happens regardless if the auto-focus enabled or disabled.  Obviously if the auto-focus is disabled on the camera body this setting will have no effect, but with auto-focus off it can be thought of as the ‘padding after the motor moves and before the camera fires‘.

Camera>Exp. Time ms> : this is the amount of time the fire signal is sent to the camera body in milliseconds. In most cases you are setting the image exposure time on the camera body so this only needs to be a very quick trigger signal (usually 72-100 ms will fire most camera bodies).  If you want to extend your exposure longer than the maximum exposure time allowed by the body by using the BULB mode on the body then this setting can be used to set the total exposure time. (for example 40,000 ms for 40 second bulb exposures).

Camera>Exp. Delay ms> : This is the amount of time after the trigger time and before the motor moves. So, basically this is the most important setting when doing long exposures. The exposure delay should be a little longer than your exposure time. To allow the camera to fully complete it’s exposure before the motor executes it’s move. (for example with an exposure of 15 seconds set on the body an exposure delay of 17000 ms or 17 seconds would be a good range)

Practical Example ‘Dark Skies’

In ‘Dark Sky’ conditions (no moon, far from light pollution) your attempting to get the most light possible so a good ‘one size fits all’ setting on your DSLR body would be 30 second exposures at f/2.8 (or wider; some lenses open up to f/1.4) at ISO 3200. Based on this exposure setting here’s how we would set up the MX2:

  • Settings>Motor Sl Mod>Interleave [enter] Sets the MX2 to ‘move-shoot-move’ mode
  • Axis 1>Fixed SMS>ON [enter] Sets motor 1 to fixed ‘move- shoot-move’ cart will move a fixedamount based on the main screen setting
  • Camera>Focus Tap ms> 1000 [enter] This adds a little 1 second padding after the motor moves and before the exposure begins
  • Camera>Exp. Time ms> 72 [enter] Enough time to trigger the average DSLR (some consumer models can take a little more time.. say 100ms)
  • Camera>Exp. Delay ms> 33000 [enter] Enough time  for the exposure to finish plus a couple more seconds. 30 seconds set on your body is not exactly 30 seconds.. in reality it’s actually a little more! Test it with a stopwatch and see for yourself!

All this adds up-to about a 34 second interval so the MX2 will automatically set the minimum based on these settings.

Don’t Forget: depending on your camera model it may need a little more or less time to clear the buffer for the next shot. Get the system started and watch that buffer light to make sure it goes off before the next shot is triggered. You don’t want missed shots…

Using Mirror Up (MUP)

By adding a repeat shutter trigger with a delay (in-between) this will allow the use of your camera’s Mirror Up function to reduce mirror slap.  Both of these settings are in the Camera menu section:

  • Camera>repeat>2 [enter] this repeats the exposure trigger cycle twice
  • Camera>Repeat Delay>500 [enter] this sets a half second delay between allowing the mirror to go up (current max 1000 ms)

Remember, the system is Live!

You can always adjust any of your settings while the MX2 is currently running.. The minute you hit enter to accept a value it takes effect in the next cycle. If you need a little more or less time in any area you can do it ‘on the fly’ while the sequence is running.

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