I think I've read whatever documentation exists for the particle effect parameters, but I'm not able to match the descriptions to the results. More likely, I'm not understanding how they work. I'm experimenting with the "rain curtain" emitter type.

The description of the "particle life" parameter says that a value of 100 will give you particles that last the entire length of the clip; but when I set the life to 100 I get particles that (in the designer window) simply flash into existence and then disappear.

Okay, so the description of the "life variation" says that a value of 50 would mean that half of my particles would live for the entire length of the clip. That might be true, but with the particles flashing the way they are it's hard to tell. If, instead, I leave the "particle life" at 100 and change the variation to 5000, then I get particles that behave the way I'd expect: some of the particles last for a long time and some don't.

Changing the speed plays into this phenomenon, because it controls whether or not the particles get as far as I want before they disappear. That makes sense, although the units are undefined.

The interactions between the parameters seem hard to control, in that the numbers don't seem to mean anything. It seems like the only way to get results anywhere near what I want is to

1. Move the scrubber to where I want to see my desired result (typically the end of the particle designer's timeline)


2. Set the emit rate and max count to get the density I want


3. Crank the life up to a very large number


4. Set the life variation to zero


5. Adjust the speed so that the particles just reach their destinations


6. Adjust the life so that they live just long enough to reach their destinations


7. Set the life variation so that some of the particles "die off" before they get to the end of their travels


8. Set the speed variation so that the speeds vary the way I want

Steps 5 through 8 are basically trial and error, and I'm not even sure the results are repeatable.

In my case, I want the particles to get to travel from the top to the bottom of the TV safe zone. I wound up with

• Emit rate: 200


• Max count: 20


• Life: 5000


• Live variation: 75


• Speed: 9.5


• Speed variation: 100

With the exception of max count, the other numbers were a combination of guesswork and random fiddling.

Note that I haven't dared to introduce keyframes.

So, what am I missing? Is there a better, more predictable, way to set these values? Jerry Schwartz