Tag Archives: Atmospheric Effects

No Fog? No Haze? No Problem!

…if you’re prepared, of course.

Please Remember:

The opinions expressed are mine only. These opinions do not necessarily reflect anybody else’s opinions. I do not own, operate, manage, or represent any band, venue, or company that I talk about, unless explicitly noted.

Want to use this image for something else? Great! Click it for the link to a high-res or resolution-independent version.

Fog and haze are sometimes unwelcome.

It’s a shame, because I love the way that atmospheric effects make lighting “rock.” At the same time, though, I have to respect the fact that some folks just can’t handle breathing a bunch of stuff that’s been shot into the air. Also – even though I haven’t done a show in a random room for a long time – I have to respect that some venues don’t (or can’t) allow “atmo.” Some places have had bad experiences with residue and dangerously-slick dancefloors. Some places have fire alarms that trip easily, and automatically call the fire department, which is bad if there isn’t actually a fire. (Seriously, if a venue says “no fog, and no haze,” you need to listen. Your life could get very expensive in a huge hurry.)

“But we need atmospherics!” you complain. “The show isn’t the same without seeing the beams!”

Hey…I get it. Like I said up there, I’m a lover of haze. Even with the simple setup that I currently use, I love how the colors from the backlights cut diagonal lines across the stage picture. If I don’t have a specific reason to keep the hazer disabled, I’m going to run it.

So, what can you do if you’ve got a beautifully crafted, beam-filled light show all ready to go – and then someone tells you that atmospherics are out of the question?

Well, it’s time for some problem solving, and problem solving is made much easier when the bedrock principles of what you’re doing are “top of mind.” What’s the basic principle in play with your light show? In my opinion:

The Beam Has To Hit Something

I’ve talked about fog and haze before, but when I did, I was writing with the assumption that people knew why they wanted some kind of “atmo.” I didn’t really get into “first principles” with that article, though.

Light beams CAN be scattered by particles that are quite small when compared to the wavelengths of visible light. This is why the sky is blue, if you didn’t know. The general problem with this as an effect is that you need a really, really large volume of those particles to get anything visible. You also need a very intense light source…something with the luminous flux of, say, the sun. (As it turns out, unrestrained fusion reactions in space are REALLY FREAKING BRIGHT.)

Anyway, “small particle” or “Rayleigh” scattering isn’t really helpful to lighting crafts-humans. Especially in small venues (but pretty much everywhere), we don’t have a lot of air to work with, and we rarely have sunlight-comparable fixtures on hand. As such, we need “big particle” scattering in order to get anything useful. This is where fog and haze come in. Even really fine haze can be enormous when you compare the particle size to light wavelengths. If a very deep red has a wavelength of 700 nanometers, then five-micron haze is about seven times larger. The “particle-size to wavelength fraction” just gets bigger as the light wavelength increases.

The point being that the light smacks into something that’s relatively large, and scatters towards our eyes. When that happens, we get awesome light beams. Liquid sky. Aerial effects. WOOT!

That is, until someone ruins our fun by saying that they don’t want fog or haze to be used. Actually, I shouldn’t really say that, because that’s unprofessional.

See, when a band or venue tells you that they don’t want atmospherics, they probably have a good reason. What’s more, they’re coming to you as a professional and asking you to make your show work within the parameters that they need it to work in. That’s what professional production techs do: They do everything possible to get their show into the parameters that the situation presents.

If the light show needs scattering to look right, but aerial scattering has been removed from the list of allowable parameters, what have you got left?

Screens, Scrims, Banners, and Drape

This is one of those things that’s obvious when you’re reading articles on the Internet, but not so obvious when you’re deep in the throes of getting a light show built. If you’re like me, you tend to focus on your specific vision for what’s going to happen, and then forget about everything else. If a monkeywrench gets thrown, going back to the basic principles of what you’re trying to accomplish can be forgotten in the mad rush to save “the original intent.” I know. I get it.

But when somebody says “No fog or haze!” you can do yourself a great service by remembering the most basic fact of what you’re going for: Light beams that become visible due to striking an object larger than the light wavelength.

If that’s the basic requirement, then I can tell you that projection screens, scrim (material that looks opaque when front-lit, and translucent when backlit), and various kinds of drape definitely fit the bill. Hit those with the lights, and you will definitely see something. Of course, you have to be ready to modify the lighting setup to make this work…and if you’re taking a show on the road, being ready for a no-atmo situation is probably a very good idea. Yes, screens and drape aren’t as foolproof as atmospherics, due to their not being “everywhere.” Still, they’re a lot better than nothing, and can actually look quite good.

For example, here’s just one kind of kaleidoscopic effect you can get with a circular screen and a bunch of colored spots. (This is, of course, exactly what Pink Floyd – and various tribute acts – have done with “Mr. Screen.”)

mrscreen

In the same vein, you can also get some very nifty looks with a “full screen” behind the band and lights arranged in an arc. This is very similar to what The Australian Pink Floyd Show did for their concert at The Royal Albert Hall. (Of course, they also had fog and haze for the movers to shoot through when they weren’t aimed at the screen – but whatever.)

arch

If you have more limited resources, you might consider “floor to whatever height” banners that you can hit.

banners

There are lots of pointers to be had about what to use as “targets.” Obviously, honest-to-goodness movie-screen material will work nicely. Light, gauzy fabrics can also be interesting, but you have to be careful if your fixtures emit a significant amount of heat. White materials provide you with the most flexible “canvas,” but you can also get creative with other colors. Depending on your setup, you may be able to hang drape from your lighting stands. Also, make sure you’ve budgeted enough time to get everything in place and tested.

(I’m sure there are a LOT more particulars to think of, but these are the biggies that came to mind.)

The point is that being denied your atmospheric effects isn’t the end of the world. In fact, it can be an opportunity to do something different and cool.


The Foggiest Idea

Haze and fog are similar, but they’re really meant for different applications.

Please Remember:

The opinions expressed are mine only. These opinions do not necessarily reflect anybody else’s opinions. I do not own, operate, manage, or represent any band, venue, or company that I talk about, unless explicitly noted.

Yeah, so, I’ve been completely ignoring the lighting categories on this site.

Sorry about that.

I guess that I don’t think as deeply about lighting as I do about audio, which is kind of a shame. Lighting is a tremendously fun art and science of its own, and I really enjoy it. I guess that, when compared with audio, I handle the lighting end of things “on autopilot” a lot of the time.

Stage lighting deserves more than that, though. It’s a crucial component of giving an audience what Cliff Bleszinski would call “The Fun.” Part of bringing “The Fun” with (and to) a light rig is to use atmospheric effects – you know, fog and haze. If you’re just starting out, though, it may not exactly be clear that’s there’s a distinction between fog and haze.

HA! Not exactly CLEAR! We’re talking about atmospheric effects and I said that things might not be clear! BaHAHAhaHAHha *snerk* HA *cough*.

I’m WITTY.

Anyway.

Fog and haze aren’t technically the same thing. You can sometimes substitute fog for haze, but going in the other direction isn’t really possible.

Here’s why.

Distribution

In my experience, the fundamental difference between fog and haze is that of their distribution through the room. Yes, the respective chemical compositions of different “fuels” for these effects may differ, and that difference may be profound. However, whatever it is that makes up fog or haze fluid is not always the primary determinant of what you’re going to get.

As a case in point, consider a particular hazer that I own. This hazer uses a water-based fluid that passes through a heating block. The heating block transfers thermal energy to the fluid, and the fluid then vaporizes. The vapor is then propelled away from the unit by an integrated fan.

If you shut the fan off, you have a fogger.

Sure, the fogger has a special talent. It can run continuously without a reheat cycle, which is neat, but it’s still just a fogger with a fan. The fluid formulation might be just different enough to affect hang-time and vaporization characteristics, but it’s still basically fog fluid. In this particular case, you can put the “fuel” in a regular fogger and the machine will, you know, fog.

Fog and haze fluids are NOT always interchangeable in this way. Putting the wrong juice in an atmospheric effects unit can wreck the machine, cause you to get serious burns, start a fire, cause the fluid to break down into dangerous chemicals, and just generally screw up your day. If you experiment, experiment wisely – and at your own risk. DON’T BLAME ME IF YOU RUIN YOUR LIFE.

Okay.

So, what kind of distribution makes fog, and what kind of distribution makes haze?

Fog is characterized by a distribution that is non-uniform and chaotic for a large percentage of the effect’s “hang time.” Haze is characterized by a distribution that is much more uniform and stable throughout it’s entire hang time.

What this means is that fog, as a general rule, tends to be generated as a clumpy cloud that visibly wisps and swirls with air currents. In the room, the density of the cloud can vary greatly from one point in space to the next. As the fog disperses, the cloud’s “point to point” density becomes more and more uniform.

In contrast, haze is generated specifically to be as uniformly distributed as possible. Any “cloud” characteristics should smooth out as quickly as possible – ideally, before the audience notices anything. Further, interaction with air currents should be as minimally visible as possible. As the haze dissipates, its distribution throughout the room should remain uniform. (In other words, the overall haze density in the room should be essentially the same everywhere, with the density dropping at the same rate at all physical points.)

The reason that you can use fog for haze, but not the reverse, is because non-uniform atmospheric effects naturally become uniform over time. On the flipside, atmospheric effects that start out with a very even distribution won’t get clumpy without a lot of work. It’s a one way street where you can start at the “fog” end and arrive at haze, but you can’t travel in the other direction.

Application

The distribution characteristics that I outlined above are what make fog and haze appropriate for different applications.

In general, fog is a relatively short-lived effect that is meant to be visible in and of itself. Haze, on the other hand, is meant to be a long-lived effect that is, itself, invisible.

Fog is meant to look like something. Whether it’s a plume of steam, magical smoke, or eerie mist, fog’s primary purpose is to be a relatively opaque, visible effect. Because fog – like haze – causes light scattering, it also has the cool side-effect of making light-beams visible. This side-effect, coupled with fog machines being traditionally cheap(er) and easy to find, means that there are lots of people who use fog primarily to make light shows more exciting. The uneven initial distribution is just shrugged off.

Haze, on the other hand, is specifically meant to NOT look like anything at all. “Ideal” haze is meant to be invisible until a light beam passes through it, and even then, the point is to see the light and not the stuff floating in the air. Haze is used to let lighting designers make the show more exciting WITHOUT having to deal with the initial clumping and cloudiness of fog.

In certain cases, these different characteristics are used together in complementary ways. For instance, haze might be used throughout a show for the regular lights, but a “liquid sky” effect might be desired at certain points. “Liquid sky” is a laser effect that relies on uneven distribution of atmospheric particles to create a stylized cloudscape. Since haze is so uniform, it isn’t much good for making a liquid sky. As such, fog would be generated only for the parts of the show where the sky effect is needed, with the haze running continuously throughout.

Clear enough? (Oh geeze, the puns…)