Lighting with Gels

A quick word about lighting gels, as they’ve cropped up a couple of times in the course so far, and I’m aware that I’ve not talked about them in any detail. They’re called “gels” as they used to be made from gelatin, although these days they’re usually made from Polyester. I wouldn’t get too hung up on that if I were you – add it to your list of things you might want to know in a pub quiz!

Gels are not really modifiers, as they won’t alter the quality of light, but obviously they do alter the colour of light. Now, you may do this for practical purposes to bring different light sources within the same range on the colour temperature scale, or you might employ them creatively just to add some colour to your shots.

Starting with colour correction, there are 3 main types – Orange, Blue, and Green. Orange ones take daylight balanced lights, like flash, and turn their colour temperature down to the same as tungsten. Blue ones do the opposite, taking tungsten lights up to daylight, and green ones are used to make daylight or flash the same colour as fluorescent tubes. Their official names are Colour Temperature Orange (CTO), Colour Temperature Blue (CTB), and window green. They all come in different strengths, with a “full” of each giving you the complete conversion either way – so all the way from daylight to tungsten in the case of a full CTO – and then in varying strengths, usually 1/2, 1/4 and 1/8.

We’ve already touched on this concept briefly when we shot with mixed light sources and added an orange gel to our flash so that their colour temperature was the same, so we don’t need to go into too much depth here. I’ll give you a couple of quick pointers though about using gels for colour correction. The first is always make sure you gel your light fully – that the gel is covering the entire light source, and no light is escaping round the sides. If you’re trying to correct a colour cast, you’ll be handicapped if some of your light is still being cast in it’s native colour.

Second, on a practical level, it makes sense to gel the smallest source you can – it’ll use much less gel, and will usually be easier to achieve. Imagine shooting an interior scene that’s lit by lots of tungsten lights way up in the ceiling, you’re using flash, but still need to retain some light from the tungstens to retain the mood. If you set your camera to daylight or flash, you’d then have to put CTB all over the tungsten lights – this may be very tricky if they’re up high! I’d suggest you set your white balance to tungsten, and then gel your flashes with CTO. Much quicker and simpler.

Of course there’s nothing to stop you using these colour correction gels for creative reasons, rather than just to balance the light colours correctly. I frequently whack a CTO or 1/2 CTO on my flash to add a warm tone to the light. Or, in this case, a full CTB to turn a white ice wall blue for atmosphere.

Gels also come in a huge range of colours, and it’s worth having a few different shades in your kit to allow you to throw some colour casts about the place. I’ve been known to do this on occasions! You can now buy really handy little kits from places like Lee filters that will contain the whole range of colour corrections, along with some more crazy colours. These may come with handy little velcro dots like these, to attach to the velcro straps you can get for flashguns. For bigger lights, you can either tape the gels in place, or clip them with croc clips or similar. Some barndoors and fittings for tungsten lights come with clips already in place for holding gels, which is handy.

A couple of catches to warn you about. Any gel will not only affect the colour of your light, but also the quantity. Look at this range of CTB filters, and you can clearly see that something like the 1/8th lets a lot of light through, but that the full CTB probably blocks at least one full stop of light from passing through it. There are in fact gels that do nothing but stop light, called neutral density filters. These are colour neutral, and come in different strengths to block light. Why on earth would you want to do that? Well, think back to when we talked about quantity, and of course, sometimes we want to reduce the amount of light – either to match the light already in a scene, or simply as a way controlling a simplistic light source. This 1 kw tuingsten light is pretty powerful, but it has no power adjustment, so if I want to turn it down, I need to either move it further from the subject (or bounce, or diffuse it) or I can keep the quality the same, but add some ND to reduce the power output.

Lastly, and conveniently since I’ve got this 1K to hand – beware of melting gels. They should be non-flammable, so there’s no risk af burning the place down, but be careful when attaching them to something hot like this tungsten light. Try and allow a bit of space between them and the hotter parts of the light, and keep your nose peeled when you’re shooting – you’ll soon smell when they start to melt! It’s even possible to melt them when they’re on flashes, but you generally have to be shooting at full power A LOT for this to happen!

So there you go, a quick guide to modifiers. I really don’t want you to get caught up in different brands, and always remember that all modifiers do is make light softer, or “harder” – although we know that in reality “harder” means simply controlling where it falls. Gels can change the colour, or cut out the quantity of light

One last word of caution, as this is something that I have fallen for over and over again throughout the years. Buying a “beauty dish” because you like what it does for someone else will only give you the same results if you use it in EXACTLY the same way. On it’s own, it will not be a magic bullet, but if you employ it just the same as the photographer did in whose work you’re emulating, then yeah, it’ll look pretty similar. Buying one, and placing it 20ft away, when the image you’re copying it from had it placed 5 ft away, will not give you the same result. Modifiers are great, they can allow you to do lots of cool things with lights in a handy package, but you can’t escape the basic rules about distance and size relative to the subject. Don’t fall down the rabbit hole of simply thinking that spending money on the latest toy will change your life. New things come out all the time, but the basic rules of physics are not about to change. At least, I hope not!

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