Showing posts with label Color Temperature. Show all posts
Showing posts with label Color Temperature. Show all posts

Flash Gels for Correcting Color Temperature: Using the Gels (Part 2)

On part 2 of this article I will be showing you some practical examples of the most common used gels CTO (Color Temperature Orange, converts Daylight to Tungsten), CTB (Color Temperature Blue, coverts Tungsten to Daylight) and for Fluorescent I will use the Plus Green (Provides a green cast when used on Daylight and Tungsten for balancing Fluorescent).

But first things first let's take a look of what Color Correction and Color Temperature means so you can get an idea how you can explore and use it.

Color correction by using color gels, is a process used in stage lighting, photography, television and cinematography, the intention of which is to alter the overall quality of the light measured on a scale known as color temperature.

Without color correction gels, a scene may have a mix of various colors. Applying color correction gels in front of light sources can alter the color of the various light sources to match. Mixed lighting can produce an undesirable aesthetic when displayed on a television or in a theater.

Conversely, gels may also be used to make a scene appear more natural by simulating the mix of color temperatures that occur naturally. This application is useful especially where motivated lighting is the goal. Color gels may also be used to tint lights for artistic effect.

The main color correction gels are CTB (color temperature blue) and CTO (color temperature orange). A CTB gel converts tungsten light of 3200K to 'daylight' color. A CTO gel performs the reverse. Note that different manufacturers' gels yield slightly different colors. As well, there is no precise definition of the color of daylight since it varies depending on the location (latitude, dust, pollution) and the time of day.

Gels that remove the green cast of fluorescent lights are called minus green. Gels that add a green cast are called plus green. Fractions such as 3/4, 1/2, 1/4, and 1/8 indicate the strength of a gel. A 1/2 CTO gel is half the strength of a (full) CTO gel.

The color temperature of light is measured on the Kelvin scale, which we may have used in our high school science classes, but have long forgotten. The scale is an extension of the Celsius scale. It’s based on the color of the light as it is emitted from a hypothetical black body.

The Kelvin scale (abbreviated as “K”) is confusing, because it runs counter to the way in which we use some photographic terms. For example, when photographers talk about adding “warmth” to a scene, they usually mean to add some reddish tones. Conversely, when photographers talk about “cool” tones, they’re referring to the bluish side of the spectrum. This logic is just the opposite of the Kelvin scale of color temperature.

At this point, you may be scratching your head, wondering how light can be described by its color temperature, well consider a log fire. When the fire/flame is at a low temperature, the color of the flame is red. At higher temperature, the flame changes to bluish tones.

Got it ?

So let’s look at a Kelvin temperatures chart for various lighting conditions. Please note that the values are approximations because many factors affect color temperature. In outdoor conditions, the angle of the sun and condition of the sky (clouds, haze, dust particles, etc.) can raise or lower the color temperature. Indoor conditions such as lamp age, voltage, type of reflectors, etc. affect the color temperature of light.

Here are some common light sources:

Note: Fluorescent light does not operate in the same manner as the black body model of Kelvin temperatures. Additionally, there are six different types of fluorescent lamps. White fluorescent lamps, for example, have a color temperature of 5200 K. That’s why it’s difficult to photograph under fluorescent lighting, even using a fluorescent filter for your film camera.

Since this is not intended to be a class about WB or Color Correction let me show you some examples I got using the gels and ambiance light.

In the following pictures you can see the several lights as well as on the background you can get a glimpse of what it would look like using the gels to correct ambiance and you can even use that to create other colors at your taste.

The weather is not so nice here in Luxembourg but it looks like when I started to get some pictures for this tutorial the sun came up ;)


Here is the setup picture and one of my cats that join me on this setup.

On camera left you have the SB-26 with gels, the Tungsten and a Fluorescent lights (I put the black banner behind the lights so you can see them changing with different settings) and on the right you have a white piece of paper so you get the feel of what the light gel is affecting and you can also see the changes it produces to the background when I change each gel.

I will be holding 6 pieces of paper that correspond to each camera White Balance I used for this testing shots this way will be better for you to understand what's going on. So what we will have is WB, Sunlight, Shade, Cloudy, Tungsten and Fluorescent.



First sequence is with CTO (Color Temperature Orange) on the flash.

Is never too much to mention that this one converts Daylight (5600K) to Tungsten (3200K), you can also find the some complements as 1/2 CTO (5600K-3800K) and 1/4 CTO (5600K-4600K).



Then to the normal CTO (Color Temperature Orange) I added a CTO 1/2 on top of the other. I made this on purpose so you can see the difference between the normal CTO and a little bit more warmer tone. You can also try it with 1/4 CTO for a not so pronounced orange tone.



Then we have the CTB (Color Temperature Blue).

This one we will use to convert Tungsten (3200K) to Daylight (5600K), as you are seeing here it's the opposite of the CTO and you can also find it in 1/2 CTB (3200-4300K) and 1/4 CTB (3200K-3600K).



Made the same thing with the CTB (Color Temperature Blue) and added another CTB 1/2 so you can see the heavy blue tone and what it happen to the lights and background.



And the last one is the Plus Green (Equivalent to Color Correct 30 Green)

This one provides a green cast when used on Daylight (5600K) and Tungsten (3200K) for balancing Fluorescent (3600K). For providing partial green cast when used on Daylight (5600K) and Tungsten (3200K) for balancing Fluorescent (3600K) you can adjust it with 1/2 Plus Green and 1/4 Plus Green.

Hope you have enjoyed these practical examples now, if you already have the Gel Pack, go and experiment yourself on different light situations either inside, outside or both.

Part 1 - Flash Gels for Correcting Color Temperature: The Gels (Part 1)

Flash Gels for Correcting Color Temperature: The Gels (Part 1)

My Gear - What you wanted to know but were afraid to ask_007Today's article is a 2 part concerning Gels.

A lot of people been asking me what are Color Temperature (CT) flash gels for and where they can find it.

On the first part I will be showing a very simple way where you can get them, in Europe, very fast and with everything you need to cover all CT areas.

On part two is all about practical examples on what and how you can use them on different situations to balance light and improve your photos.

I ordered 4 days ago a Filter Pack and an Effects Pack Gel from fellow photographer Jason Lane at flashgels.co.uk
at first I wasn't very sure which size to order because he has 2 sizes for different flashes heads, but everything is so well explain on the web site that I instantly figure out which to choose.

After exchanging some emails with Jason I realize that he's a Lone Ranger on this matter. He started this idea when David Hobby talked about it on the London seminar and since then he has been cutting the tinny little pieces of gels to match our flashes. Until now, I think, he's the only "store" who has them hand made, pre cut and shipped for and to the Strobist community and in Europe.

In another words he's getting us the gels we need to improve our photography and make them also in packages of Color Temperature and Effects.

The filters in the packs are cut from quality Lee Filter rolls and are 14cm long.
The 4cm Normal filters should be suitable for most Nikon, Pentax and Canon flashes (The one I ordered for My Canon 580EX and Nikon SB26) and the 5cm Wide are for flashes with larger lenses, for example the Vivitar 285HV.

He also have the Gels cut to 119mm diameter circles to fit the diffuser of the Quantum QFlash, if you have on of these units ;)

You can choose the Packs with Velcro or without. Packs with Velcro include 100 pre-cut 12mm hook dots for the filters, and 4 x 10cm strips of Velcro loops to stick on your flash. Loops are the soft side, hooks the rough plastic part of the flash.

Ball Bungees

And if you are going to buy, from Jason, do not forget to order a pack of the so hard to find Ball Bungees.

You may ask - "What are they use for?" - Take a look at these two brilliant articles here and here to know all about them.

At last minute, before this article went online, Jason added a new link on his web site where you can choose your own gels and make your own packs, he calls them Pick'n'Mix, they are packed on an envelope of 5 units each, you can get the same 4cm and 5cm gels with some extra CTB and other colors and add to the order some extra Velcro Hooks and Loops.

After this great last minute news the pack only depends on your color choices, just let him know what you need and he will make you the customized packs.

Jason Lane really do things a la Strobist way. You have everything you need in just one order and you get them very quickly. I was very impressed with the service and will recommend this to everyone who needs some Gels and Ball Bungees.

Gels Part1_001

Here is the package I received on the mail. Very good you can even use it as a box to store your filters while not in use.

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I've ordered the 4cm Gels pack with Velcro (£10.00-€14.02) and the Effects pack (£5.75-€7.98) that's £15.75 (€22.00) plus £1.30 (€1.80) shipping to Luxembourg total £17.05 (€23.80) paid through PayPal.

I think the price is really fair compared to all the cutting and packaging.

Gels Part1_003

Here is the Gel Pack and the Effects pack out of the shipping card box.

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A complete description of the filters on the Gel pack:

Full color Temperature Orange (Ref.Lee 204) 10units
Plus Green (aka Window Green) (Ref.Lee 244) 10units
Half color Temperature Orange (Ref.Lee 205) 5units
Quarter color Temperature Orange (Ref.Lee 206) 5units
Full color Temperature Blue (Ref.Lee 201) 5units
Half color Temperature Blue (Ref.Lee 202) 5units
.3 Neutral Density – 1 stop (Ref.Lee 209) 5units
Flame Red (Ref.Lee 164) 2units

Velcro version includes 100 pre-cut 12mm hook dots for the filters, and 4 x 10cm strips of Velcro loops to stick on your flash. Loops are the soft side, hooks the rough, plasticly part.

You can find more details and photos of the Filter Pack here.

Gels Part1_005

and the Effects Gel Pack have the following:

Dark Green (Ref.Lee 124)
Yellow ((Ref.Lee 101)
Pale Navy Blue (Ref.Lee 143)
Light Red (Ref.Lee 182)
Magical Magenta (Ref.Lee 795)

You can find more details and photos of the Effects Pack here.

Now let's make some DIY on how to apply the Velcro to the flash unit. Skip this part if you already know how to do this.

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I always like to apply Velcro after putting the Stofen on the flash this way it will not block it by any means and I can easily attach and remove the Stofen.

There are so many threads on the web about the Velcro attachment, some say they do not glue the Velcro, others say the flash stays sticky when you want to remove it and lately the talk bends to cable straps.

Take a look at the Flickr discussion group here and see what suits you best. Well me I prefer them sticky so let's stick them up :)

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With the Stofen on the flash measure the length of the soft Velcro you will be using and cut it.

Gels Part1_008

Now apply it to the flash.

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Do the same thing all around the flash and remove the Stofen. I like to make it all around just in case later on I will need to use a flag or a gobo to any side. You can ask what the hell is a gobo ???? Oh, no :( ...

No problem, take a look in here and you will find your answer :)

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Now the doted had Velcro.


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They go to each side of the gels, oh and by the way the gels fit perfectly on my Nikon SB-26 and Canon 580EX.

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Now you just have to put the gel over the flash from side to side, you can even put the stofen over the gel to get the tone to bounce all over (in case you need that).

Gels Part1_013

Tip: I normally put another piece of Velcro on the other face of the gel. I used here some pieces of the soft Velcro I've cut from the flash part.

Gels Part1_014Gels Part1_015

Here is what looks like. The circle are the hard Velcro and the rectangular are the soft Velcro.
On the other image I had previously done this with my other gels but then I only had the bigger rectangular Velcro. Well it's the same thing what suits best is what it counts.

Now you my say why do I need them on the both sides with soft and hard Velcro?

The answer comes with the next pictures...

Gels Part1_016

Simple... got it ?

Text version: You can use one gel on the flash while having another one (or several) attached beneath or above. This way would be very easy and quick to change them and you don't need to be running to your bag each time the room temperature changes say Fluorescent to Tungsten or vice versa ;)

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Here you can see them sticked together because one side has soft Velcro and the other hard Velcro.

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This image shows you what they both would look like on my Nikon SB-26 when stick together.

I have made some other articles concerning the gels and gel packs that you may look into them.

Lee Filters Flash Adapter_011

If you do not like the idea of the Velcro then you can make you own adapter take a look at the article DIY: Lee Filters Flash Adapter.

580Ex DIY:Color Gels_05

Or if you also do not want an adapter and you own a Canon 580EX or the new 580EXII you can make your own by reading this article DIY: 580EX and 580EXII Color Gels Printing Diagram.

StrawsSnootsWColor_005

You can even get your Black Straws Grid Spot with them check the article here.

Snoots with Colors (Part 1)_18

Or the Snoots. Article here.


I think this full package is very good and it has all the essential CT and Effects that you may need on a daily basis.

The only thing I missed on the Filter Pack was the lack of the Half Plus Green (245), the Quarter Plus Green (246), the Quarter CTB (203) and the .15 Neutral Density Half Stop (208) if they were to be included, in a near future, this would be the most complete gel pack for Strobist photographers even without these it still is one of the best gel packages I found over several online stores.

Delivery very fast and secure it only took 4 days from the UK to Luxembourg.

So what are you waiting for go and order one pack and be prepared for part 2 of this article "Flash Gels for Correcting Color Temperature: Using the Gels (Part 2)"

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Update 31-12-2007

I was informed by Jason that starting January February 2008 the Colour Correction Gel Pack contains a total of 50 filters made up of 5 each of the following colours:

CTO - Full Colour Temperature Orange Lee 204
½ CTO - Half Colour Temperature Orange Lee 205
¼ CTO - Quarter Colour Temperature Orange Lee 206
CTB - Full Colour Temperature Blue Lee 201
½ CTB - Half Colour Temperature Blue Lee 202
¼ CTB - Quarter Colour Temperature Blue Lee 203
Plus Green (aka Window Green) Lee 244
½ Plus Green Lee 245
¼ Plus Green Lee 246
.3 ND - 1 stop neutral density Lee 209

and the Effects pack a total of 30 filters made up of 5 each of the following colours:

Dark Green (Ref.Lee 124)
Yellow ((Ref.Lee 101)
Pale Navy Blue (Ref.Lee 143)
Light Red (Ref.Lee 182)
Magical Magenta (Ref.Lee 795)
Pale Blue (Ref.Lee 063)

Also available are Neutral Density filters pack 10 filters consisting of 5 each:

.6 Neutral Density 2 stops (Ref.Lee 210)
.15 Neutral Density ½ stop (Ref.Lee 298)

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You now have a full available Gel pack without having to go and search for them elsewhere.

I believe this is a very good place to get your gels and correct me if I'm wrong the only place where they are designed for your flash.

If your flash is not mentioned on the web site just send Jason an email maybe he could make a custom ones for yours.

Take a look on what effect your gels could have on part 2 of this article.

Part 2 - Flash Gels for Correcting Color Temperature: Using the Gels

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