There's a LOT to be said here so I'll start and others can chime in.
First you have static gobos. These are the ones you put in a frame and
drop in the slot. These are used for realistic effects like leaf patterns, a shaft of light through a window, or the name of your theater. They are also used out of focus to produce interesting texture in the light.
Lighting designer 101 is a bunch of instruments with Jungle Leaf gobos way out of focus. It doesn't produce a
clear pattern but it makes the light look more realistic and interesting to the eye.
Secondly you have your rotators.
Rosco,
Apollo, and
Gam all make good ones. They come in single and double. This means one or two gobos. You can spin them in different ways. The best (i.e. most expensive) rotators allow you to rotate two gobos in different directions at different speeds and stop them at specific locations (a feature called indexing that is often not important but occasionally critical). By varying the speed and direction of rotation you create a wide variety of effects. You can further alter the look by changing which of the two gobos is in focus. Finally if you really want a cool look you
throw a static
gobo in the
gobo slot while the rotator is going. Again adjusting focus, speeds and directions.
For a great tool to get a feel for how this looks check out this
website. This tool lets you choose two rotating gobos and a static
gobo, rotate them,
play with focus and even
gel color.
Also go check out the
Creative F/X Guide from
Apollo. They show you a variety of recipes for specific effects and a video of what it actually looks like.
The
Rosco Infinity is a completely different beast. It sits in the
gel frame slot far out of the
instrument's ability to focus. It's a great way to put some movement into a scene without making it spin. For example a leaf
gobo in the static slot and the right wheel in the Inifinty and the leaves will blow around in the breeze a
bit. I used it them some really cool rain in my last show by using it with a static
gobo.
Finally there are some unique products like the
Apollo Smart Move Vertical, the
Gam Film Fx, and the
Rosco X-effects. All do very specific effects really well but are pricey and sort of limited. With a little practice you can get effects almost as good out of a rotator.
Finally there is the
Rosco Image Pro and the
Selecon Pacific. The
image pro is a kit that allows you to print your own color gobos on special media in your printer. It goes into a cooling device that holds your color
gobo. These are pretty good but the special media costs around $5-$10 a
gobo I think (that may be wrong). A more expensive initially but better in the long run option, is using a properly equipped
Selecon Pacific ellipsoidal lighting
instrument. With the right lamp setup and a special
heat shield you can print your own gobos on standard color
transparency film that you buy at the office store for about a buck a sheet.
That's all for now I'm tired. Maybe somebody else can talk about the actual materials,steel, glass, custom, dichroics, texture glass, donuts,
etc...