The Avolites Discussion Forum

hi all,
I am a new pearl2004 op from china and nobody in this town can teach or help the puzzles I met.sSo I tried to get help from here.My question is how to make the moving heads move like a real circle?however,thers is a shape in the desk,but its movements like a"8".Then how to make it?thanks a lot.

That just has to do with the starting position you're using, probably 50/50 pan/tilt.

A circle drawn like this (starting from the top):
- down and right
- down and left
- up and left
- up and right

The movinghead is going to make exactly this movement, but due to the starting position this might not result in a circle figure being "drawn". When pointing straight up/down this will indeed result in an 8 figure; and you only need a little tilt offset and a pan swing to get a circle.

Just picture the mathematical way to draw a figure in your head and you'll see the moving heads behave like they should, it's just the offset which sometimes messes with the pattern being drawn Therefore I find the "circle" description of most shapegenerators kind of incorrect. Some other consoles use 'pan sine' and 'tilt sine' to describe the pattern being output, and that's a better way in my point of view.

The most common reason for not being able to achieve a circle is because a moving head is mounted unusually at a 90degree angle to stage. ie. with base vertical/hung on the front of a truss. In this orientation a circle would be achieved by tilting the head and continuously panning the unit, which is not possible.

Ideally you should always mount a moving head with base horizontal and all tails/displays pointing in the same direction.

I thought a moving head could only do a fig 8 due to the fact it has a hard stop at it;s far left and right positions, and only moving mirrors could do the complete circle. Not true?

A moving mirror has the same restrictions - actually even more so.

But, yes, that is the reason why if a moving fixture is hung in an unconventional way you cannot achieve a circle. Or at least not easily.

AFAIK the only fixture that could ever achieve constant pan was the Coemar NAT.

And the GLP patend-light offcourse