Lighting 103: How to Safely Gel a Speedlight

Abstract: Heat buildup can melt your gel to your speedlight. Here is how to avoid it.

Do you work mostly with speedlights? If so, congratulations. Gelling your lights is going to be quick, easy and cheap. The fresnel lens on your speedlight (where the light comes out) is only about 3-4 square inches. And that is all you are ever going to need to gel on a speedlight.

As far as how to attach the gel, you have several choices and all are simple. But there are also a few things to watch out for, unless you want your gel to be permanently heat-welded to your flash.

Attaching a Gel to a Speedlight

The first thing to know is that you'll want complete coverage. Picture the beam of light as it eminates from your flash, and make sure all of that light passes through your gel.

Some flashes, such as the legacy LumoPro LP180 shown above, have slots or clips to hold gels. This leaves a little gap between the flash and the gel. It's okay — even preferable — if you have have air gaps at the top/bottom or sides. We'll get to why in a moment.

If your flash does not have clips, you can either gaffer tape or rubber band the gel (or gels) to your flash. There is no need to buy little special-made gel holders for your flash. They are a solution without a problem. Take the money you would have spent on that and spend it on gels instead.

What Could Go Wrong?

Funny you should ask. Suffice to say the caveats are all about heat dissipation. You do not want a lot of heat to build up between the flash head and the gel. Mind you, gels are made to absorb heat. But most people underestimate the heat that can quickly build up as a gel absorbs a portion of the energy (AKA heat) from your flash.

Fun fact: Technically, you don't even need a gel on the front of your flash to fry the plastic fresnel lens. If you are using, say, an external high-voltage battery (for faster recycle times) and firing a lot of high-power pops in quick succession, this can happen:

That is what a melted fresnel lens looks like. Not good. And there wasn't even a gel on this flash, which just goes to show you how much heat can be generated by pushing your speedlights. Most modern flashes today have built in thermal protection circuitry, but some don't. And almost no flash older than 10 years has it. So please be careful.

Here are some contributing factors when shooting with gels that can cause you to permanently heat-weld your gel to your flash:

• Shooting at high power settings: say, 1/2 or full power.

• Shooting many pops in quick succession

• Using dense gels that absorb a lot of light (and thus, heat): think dark blues and deep reds.

For some reason, deep reds love to get all melty on you. It makes sense, as they are very dense and thus absorb a lot of light. So you often need to crank up your power levels on the flash to get the job done, setting up a vicious cycle for heat dissipation.

Play it safe and leave an air gap. And even so, mind your shooting pace at even modest power settings (1/4 and above).

The exception is when using very mild, such as the Rosco 08 warming gel pictured above. Unless you are ripping full-power pops in fast succession regularly, you can pretty much leave that sort of gel taped to your flash head with minimal if any gap. I have done that for years with one of my flashes, which I have designated as my pre-gelled key light for quick setups.

But in general, it's best to play it safe and air-gap. And even so, keep an eye on your gel if you are engaging in one or more of the above risk factors.

For speedlight shooters that pretty much sums it up. You get off easy today. No matter what kind of modifier you are using, you can get by with the small, cheap, speedlight-sized gel kits. Umbrella, softbox, grid, beauty dish—it doesn't matter. Always gel at the flash head itself with speedlights.

Just make sure to mind the gap.

Big lights, with their different tube/bulb architecture, high power levels and various light modifiers, are a different animal altogether. We'll tackle that next.

Next: How to Gel Big Lights


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