Indexable Gobos ???

[dmxeater]

Sorry for this silly question but what are indexable gobos ?

 

thanks, stuart

[PDD]

On a moving light, you can tell the gobo which way up it should be. Basically.

[sam.henderson]

You can basiclly spin the gobo through 360, useful for example company logos inside a ml if you wanted to project onto something.

 

Sam

[Jamtastic3]

I've been wondering this too. So a fixture which is says it has indexable gobos means it has gobo rotation? Why can't they just say gobo rotation, sounds better to understand than indexable gobos.

[LiteMoves]

It's always been my understanding that "rotating" suggests the ability of the gobo to spin continuously, whereas "indexing" means turning it to a different stationary position.

[dmxeater]

Ahh ok I see, so its kinda like a fancy word for rotation ! but can stop at a certain place.

 

cheers, stuart

[paulears]

On something with rotating gobos, if you have something like an off-centre small single spot, like some of the old macs, you set up a scene with a few of them. when you go back, it's wrecked because if they've been spinning, they won't be in the same place. If they are indexable, they still spin the same, but can be made to repeat a position. A pretty important difference

[MrDan]

I've been wondering this too. So a fixture which is says it has indexable gobos means it has gobo rotation? Why can't they just say gobo rotation, sounds better to understand than indexable gobos.

<{POST_SNAPBACK}>

 

No, indexing and rotation is not the same. Most (new) fixtures have gobo wheels that have different modes exposed on one or two DMX channels.

 

Usually the first channel controls the gobo wheel itself. The most common modes are "scroll", where the wheel (not the gobo itself) 'scrolls' through the gobos, giving you the oportunity to show partial gobos. (I'm not sure if someone actually uses that, but in color wheels it is used). The second mode is usually "fixed" gobos, where the gobo wheel 'snaps' to the gobo. Therefore when you fade from one gobo to the next it 'snaps' to the next gobo.

 

Two other very common modes for the gobo wheel (not the gobo itself) is that the wheel can spin forward and backward in different speeds. Some lighting fixtures have additional modes for the wheel like shake, random gobo, and so on.

 

All the above modes are usually on one single DMX channel and affect the wheel itself not the gobo. One the second channel you have indexing/rotation for the gobo itself.

 

If you choose "scroll/indexing" on the first channel then the second channel would control the index of the actual gobo, giving you the exact radial position of the gobo. E.g. you can make two cues/sceens, one with the index (radial position) on the left, and the second cue/scene with the index (radial position) to the right. If you now fade between the cues the same gobo will be shown but it will rotate from one "radial position" to the next. Can you follow?

 

Now if you e.g. choose "scroll/rotation" on the first DMX channel, then the behavior of the second DMX channel will change from "Indexing" (radial position) to "Rotation". The gobo itself will rotate (forward or backwards) based on the value of the second DMX channel in different speeds.

 

Most controller don't expose all that functionality in a userfriendly way, so that it gets very hard actually to use all the features of a modern lighting fixture.

 

One example of the above gobo functionality would be a MAC 550.

 

Dan

[Jamtastic3]

yeah I see what you mean - I have 4 CP Miniscan HPE's and channel 2 controls the gobo rotation. If you bring the fader up between 0% and say 60% you can index the gobo and if you bring the fader higher, the gobo will begin to rotate slow to fast one way and then slow to fast the other way.