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I'm experimenting with filters over on-camera flash to better match the ambient light. I'm having good results using CTOs (Colour Temperature Orange filters) with sunlight, for example.

When I'm tasked with shooting indoors, I have an anxiety about confronting older fluorescent lighting that produces a green cast. It hasn't happened yet, but I'd like to be prepared just in case it does. So, I'm wondering what is the best general purpose daylight-to-fluorescent flash filter to carry?

Lee offer a "219 Fluorescent green"; however, the description is this: "General tungsten to fluorescent correction for use when fluorescent colour temp is unknown, to provide medium correction." Although, on the Lee website the colour seems to appear as a pale green, in actually the filter is much darker. I'm assuming this is because the filter has to changing orange tungsten lighting to green fluorescent-coloured light. So, I expect the 219 will be overkill on a daylight-balanced flash.

From googling I see a "Lee 244 Plus Green" is perhaps a possibility. However, the description on Lee's website — "Used on daylight and tungsten light sources to provide green cast when used in conjunction with discharge lighting. Approximately equivalent to CC30 green camera filter" — makes little sense to me. There's no mention of using it to balance flash for fluorescent lighting.

Can anyone with experience say, which general-purpose daylight to fluorescent filter, or filters, it'd be wise to carry?

(I'm using digital, so I don't need to worry about a compensating filter over the lens. And, I have a preference for Lee as their filters are available in large sheets, cost next to nothing, weigh even less, and, equally importantly, there's a stockist just around the corner from me!)

  • In my experience, any auxiliary flash is much more powerful than a typical room's fluorescent lighting. The flash will dominate. A green cast is really only a problem when you don't use flash -- and that can be compensated for with a DSLR's white balance setting. – user8356 Feb 27 at 14:17
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    This sounds like the typical trade show scenario, where you want "just a schmear" of off camera fill flash combined with existing LED or flourescent top lighting, in order to not ruin the lighting mood but avoiding drowned out or literally lackluster details .... – rackandboneman Feb 27 at 15:59
  • Could you define CTO (I had to google it)...What is CTO in photography? The main color correction gels are CTB (color temperature blue) and CTO (color temperature orange). A CTB gel converts tungsten light to 'daylight' color. A CTO gel performs the reverse. – dmkonlinux Feb 27 at 18:10
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    @dmkonlinux: Changed question as requested. CTO is also sometimes taken to mean "Change to Orange". Typically, CTOs come in Full, 1/2, and 1/4 variants (also sometimes 1/8). A full CTO is very orange and therefore casts a very orange light. The 1/4 (or 1/8) CTO has the least effect being a lighter orange colour. Putting a Full CTO over a flash can replicate, or match, light from a setting sun, for example. Or a 1/4 CTO can be used to warm the light a little on an overcast day. Having a set of CTOs yields a lot of versatility for little money and weight. – mooie Feb 28 at 11:28
  • @rackandboneman: That's exactly it! Just a little kiss of light to enhance, rather than overwhelm, the ambient lighting. – mooie Feb 28 at 11:30
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Lee has large filter swatch samples for complete no-brainer pricing. They are actually large enough for misuse as flash filters but they should also be good for selecting what kind of sheets to acquire for good.

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I carry a Rogue Flash Color Correction Kit that was given to me at a demo once. It's a bit pricey at $30 for a pouch, sturdy rubber band, and 3 each of: ¼, ½, and full CTO; ½ CTB; plus Green; 1 stop diffuse. But it gets the job done, and is convenient to have around. When my filters got too wrinkled and torn, I just ordered sheets of CTO and green and cut more of my own.

For balancing flash with fluorescents, Rogue suggests the following:

Plus Green gels are used in combination with CTO gels to color balance flash to fluorescent ambient light sources.

  • Use Plus Green + 1/2 CTO for 3,600K fluorescent tubes
  • Use Plus Green + 1/4 CTO for 4,300K fluorescent tubes
  • Use Plus Green for 5,700K fluorescent tubes

Don't forget that each filter layer will cause a 1/2-stop loss from the flash (or 1-stop for Full CTO), so add that in to your flash power calculations.

  • Have you ever used the combinations recommended by Rogue under fluorescents? If so, how did it work out? – mooie Mar 1 at 19:35
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    @mooie I've done it a few times, and was pretty happy with the results. But I've more often provided less than recommended (i.e., green + 1/4 CTO when it called for 1/2 CTO, or even just stacking a couple greens). Obviously, the more time and effort you spend trying to match lighting color, the better the overall results. But I find that matching fluorescent lighting is becoming easier because fluor. mfrs. are making the bulbs with better CRI than they used to be, so I don't have to be as precise. Still, I'm happy to have the filter selection on hand in case I'm in a place with crappy tubes. – scottbb Mar 1 at 23:31
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1) We need to make the white of the flash greenish, so it blends to a normal office fluorescent light.

2) We do not know how greenish the light is.

Solution) Get a light greenish filter so you can stack several layers if necessary.

Let's take a look at Lee's page:

http://www.leefilters.com/lighting/technical-list.html

The 244 clearly says: Used on daylight (And tungsten)

But I would not use the full color, so I would go for the 1/2 (245) or the 1/4 (246) so you can cut 2 or 4 pieces of it, and stack them as you need.

Do not use the "Tungsten only" that is too strong and it is to correct an orange tone light source.

  • Do you have any experience of stacking these filters? Do you know if stacking two quarter-plus-green filters would reduce the light transmission any more than using a single half-plus-green? – mooie Mar 1 at 22:14
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Let’s break down the sentence from Lee:

“Used on tungsten and daylight sources” means you can use the gel on a flash (your flash is color balanced for daylight) or even a tungsten source, such as a regular lightbulb.

“When used in conjunction with discharge lighting”. Flourescent light tubes are discharge lights. It is a flourescent discharge process that generates the light.

So the translation of that sentence is “you can use this to gel your flash when mixing its light with flourescent light”

The cheapest thing is to buy the Lee gel filter sample book and cut out the filters you need and gaffer tape or Velcro them to your flash head when you need them. You can layer gels to match stronger green lights. Or buy a gel correction set designed to work with a flash modification holder system like Gary Fong (this is what I use).

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    Thanks. I looked up discharge lighting. It seems gas-discharge lights can emit many colours; it would, therefore, be helpful for Lee to qualify what they mean by discharge-lighting and say something along the lines of "discharge lighting that emits green light, such as fluorescent lighting". (That's assuming there are other types of gas-discharge lighting, besides fluorescents, that also emit green light. Should that not be the case, then Lee only needs to specify fluorescent lighting and could not mention discharge lighting at all!) – mooie Mar 1 at 23:19
  • Do you have any experience of using green filters in conjunction with fluorescent lighting the you could share? – mooie Mar 1 at 23:22
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    Yes, I was shooting under fluorescents inside an office. I gelled two Canon 580EX speedlights with mid green filter to match the fluorescent light (took a test shot with a gray card to verify). There was a window in the scene. I lowered the (opaque) blind and it became an interesting secondary blue light in the scene when corrected for white balance (set in camera, but I was shooting RAW so it was just easier to see the effect) – the_limey Mar 2 at 3:59

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