What Could Go Wrong? Priority and Background

I was asked to create and run a Paparazzi effect on a fader this past week.  Since I’m relatively new to film, I didn’t yet have one created, so I grabbed an intensity effect, applied it, adjusted the timing a bit and then recorded to a submaster when the Gaffer/DP were pleased.  When I tested the effect from the submaster, it didn’t work.  I’d like to use this “simple” effect as a way to talk about Background values and Priority and how they interact with things in sometimes confusing ways.  Though this example is on the Eos console, the principals should transfer to any console.  Let’s dig into the details.  


Background values- even when a light isn’t on, the console is telling it to do things.  It may set all the LED emitters to full so when you bring the intensity up, you see light. It may be telling a moving light to point straight down.  There are many things happening on fixtures that you may have not yet told to do anything yet in your show file.  Of course, there are also background values for fixtures you have programmed earlier and told the intensity to go out. 

Priority- Since modern consoles are optimized so you can tell one light to do things from multiple cue lists, priority is one of the ways the console decides which list gets to be in charge of the light at any moment.  Users can reassign higher or lower priority to list and submasters to get the result they want.

HTP- Highest Takes Precedence.  Lists and submasters can be configured so that the highest value will have priority.  House lights, for an example, should always have this.  If two things are telling one fixture to be at an intensity, for example, the highest will get control of the fixture.

LTP- Latest Takes Precedence.  Lists and submasters can be configured to essentially “do what the console JUST told you to do”.  This is how concerts and other events with multiple cue lists typically function.  I think of it as a temporary higher priority.


I was in a cue stack that was holding all the look on set at that moment.  So there were background values recorded for fixtures that weren’t on.  The fixtures in question were Vortex4s in 4 pixel mode.  So there was a “Master” intensity and “Cell” intensities for each pixel.  My effect was basically an instruction to go to full then restore to the background.  When I was building the effect, I told the cells to go to zero.  In Live, it worked, but as playback from the submaster, it didn’t.   

Eos automatically configures submasters to be HTP.  Since the profile from the console was telling the individual cells of the Vortex to already be at full, all the cells came to full and locked on.  Why?  The background value was already set to full, so the effect was telling the lights to go from full to full.  Not the point.  How many ways can we fix the issue?  The following is a non-exhaustive list to hopefully give you insight that will help you troubleshoot issues like this.


Simply change the submaster to be LTP and all of a sudden, it works.  The submaster already had hard zeros for each cell, so by telling the console that this list is LTP, it doesn’t have to work so hard to make instructions from the Main Cue List coexist with this submaster.

Background A

Edit the current cue so the fixtures have all their cells at zero.  That way, the effect would work correctly, since the effect goes to Full and then releases the cell to the Background state.  I prefer to not do this since I may (and did) end up bringing the effect back and I wanted the effect to work no matter what I’ve done in the main cue list.

Background B

Edit the effect so it doesn’t have a Background instruction, but a hard zero.  Instantly works, since now it really doesn’t matter what the main cue list is doing.


Change the submaster to be a higher priority than the main cue list.  Even with the Background instruction in the original effect for the low value, and even with HTP still selected, this places the submaster in a position to succeed because it gains more control over the background value from the cue list because we told it to be more “important”.

Hopefully this provides some useful insight into how something “simple” can require a little more depth of knowledge of the board to make it work.  I highly recommend you playing around with Background and Priority to find out how they work on your console and with your work flow.  

Oh- and if you are wondering why there is a second Background instruction in my effect, I find it’s a great way to give more negative space in an effect if that’s what the gaffer wants.  

What are some interactions that have surprised you over the years with your console?  You know- how adding this and that didn’t result in what you expected.  Hit me in the comments.

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