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kgallen

Snap-fade chase makes fixtures flicker

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Documenting for prosperity...

Whilst programming a show the other day I set up a simple 2 step chase on a single generic channel to do a 'flicker'. I found that if I set the chase type to the snap-fade (|\) profile, it caused some LED fixtures in the rig to blink at the step change point. These fixtures weren't changed at all in the two steps. The desk was in full mode. If I set the chase profile to the snap-snap (|-|) setting I didn't get the blink. Shame really as the snap-fade setting was much better for the effect. Software is 10.12.

Kevin

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Hi Kevin,

 

Strange, could you identify if the blink was as the channel hits full or part way through the fade out?

Could you let me know the DMX address of the lights as well.

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It seemed to be at the transition point between the steps, so I think at the snap on point (i.e. after the fade down) and at the top of the fade (i.e. after the snap). Lights were in significantly different locations, so weren't side by side to compare exactly. The generics were front/cross light and the LED backlight, so could see one or the other in peripheral vision. The generic (just a pair of tungsten PAR16s) that was intended to be the only one changing was channel 9/DMX 9 and the LED fixture I definitely saw blink is up at DMX 120 (fixture 2). There were other LED fixtures in the rig at brightness 0; I didn't see these come on at all, just the one that was on blinked off.

When the show is done I could probably create a showfile. Actually I could send the one for the show as now and you could edit the chase cue to change the chase fade profile if you like? I understand this desk is well out of production, so I'm not expecting you to spend on any time on this really!

Thanks, Kevin

 

Edited to correct which LED fixture it was (2) and DMX base address (120). There was only this LED fixture on for the Q in question, the others were at brightness 0% [and didn't blink on].

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Here's a showfile. Cue 67.5 is the one in question. What I've done for this upload, is to edit the latest showfile I'm using in the theatre, on the Phantom Frog, and to edit the Q67.5 chase to snap-fade profile (in the actual show it's snap-snap because of this issue). Since I'm at home now and edited this on Phantom Frog, I haven't tested this on the real rig to ensure the effect I'm reporting exhibits on this showfile, but hopefully it would - maybe you have a DMX sniffer to use on a real Fat Frog DMX output?

 

Thanks,

Kevin

 

ps Note also this is Q67.5 because try as I might, I couldn't edit my previous scene Q67 to make it a chase type, so Q67 got deleted and Q67.5 created instead!

 

ETA Correction: Only Fixture 2 (an LEDJ 9Q8) is used in Q67.5. It's at brightness=34%/green=255 in both steps of the chase. It's at DMX 120. Other LED fixtures in the rig are at brightness 0% in all steps of this Q.

 

ETA I didn't see any of the other generics flicker, but I'd say the blink was too quick for tungsten to respond, but it was obvious with the LED fixture. The generics use Betapack 1's and 2's (analogue from a Demux48) and the LEDs are fed from one output of a Chauvet DMX optical splitter and the Demux48 is fed from another output, so there is a degree of isolation between the DMX feeds to the two luminaires involved in this query. The LED DMX chain is terminated in the last of 5 daisy-chained fixtures.

 

This picture shows a bit of an oblique shot of the scene. The generic of channel 9 is that lighting Dorothy/Tinman etc behind a gauze and the LED fixture 2 is producing the green backlight on the skeleton character on main stage to the left. The bottom of the LED fixture can just be seen as the highest green bright spot to the upper centre-left in the picture.

 

http://www.pixelsintime.co.uk/Category/The-Wizard-of-Oz/i-zTcBpbR/0/X2/The%20Wizard%20of%20Oz-232-X2.jpg

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