Dimmer vs. Shutter?

[etchonmind]

Is there a difference between Dimmer and Shutter for LED based fixtures, ie scanners with white LED + colourwheel or RGB LED based effects ?

Some of my LED-based fixtures have both channels, so I wonder:

- Is there a difference in speed (as I didn´t spot any)?
- Will dimmer or shutter put more stress on the unit, does either have an effect longevity?

I´m after rhythmic patterns, synced strobes (low to mid speed) and could either
- leave the shutter open all time and just set dimmer between 0 and the desired value
- Or I could set dimmer at a given brightness and open and close the shutter.

It´s the same amount of programming effort and data being transferred, so what are reasons to do it one way or the other?

[GGGss]

- Is there a difference in speed (as I didn´t spot any)?
- Will dimmer or shutter put more stress on the unit, does either have an effect longevity?

-> LED fixtures work with PWM and an internal frequency of 400Hz is often seen as standard. (On PRO material this internal frequency can be altered for broadcast reasons light not interfering with framerate of video)
So - go figure what stresses the LED's more ...

I´m after rhythmic patterns, synced strobes (low to mid speed) and could either
- leave the shutter open all time and just set dimmer between 0 and the desired value
- Or I could set dimmer at a given brightness and open and close the shutter.
It´s the same amount of programming effort and data being transferred, so what are reasons to do it one way or the other?

It is very convenient to have a master dimmer in your fixture -> with this channel you set the overall power your fixtures emit onto stage. (Fine tune between all fixtures)
I'm quite sure you shutter channel already has some strobe modes built in.
So yes mis-use the shutter channel to create your own strobe mechanisme.
This is the way I should do it also.

[etchonmind]

Thanks for the clear explanation! So strobing at 20Hz max is more like child´s play for the LEDs involved, problem solved

That said, I assume fixture internal strobe functions save many on/off messages to be sent for fast strobes, unfortunately the internal strobe functions are hard to sync and beat-match. So up to a certain strobe speed (8th or 16th notes at 130-150BPM and don´t ask about triplets) when light and sound are easily perceived as "in tempo" or not, I will go with external strobe signals via QLC and use the internal strobe functions when things are too fast to perceive as synced anyway.

As for fixtures, some of mine have that dimmer/shutter channel combo, ie chauvet intimidators (barrel scan and spot duo). They have a single white LED with colour wheel and I would assume no physical shutter. It´s still nice to set brightness independently from on/off/strobe, I didn´t really think of the fine tuning yet, as I´m still in the delevopment stage with lights being full on or off. Others fixtures, like the various LED bars, are in full pixel control mode and will need external strobing anyway (eating quite a bit of bandwidth). But those are just beat-matching and don´t go into strobe territory anyway - they are enough of a bus hog with RGB matrices anyway.

Thanks for clarifying things!