You can use some gels (colour filters) for correction, Here’s an example.
Take this: I am lit pretty much OK by my flash, and with the camera set to FLASH white balance,, but the background is a tungsten light, so it looks red. I happen to like that, but what if I want that background to look normal, white, the way it looks to me?
Well… can I not just set the white balance to Tungsten?
No, because then, while the background would look good, the parts lit by the flash would look all blue, like this:
Part 1 of the solution: make the light on me come from a tungsten light source too, so we both look red. We do this by adding a CTO (colour Temperature Orange) to the flash.
Part 2 of the solution: Now you can set the white balance on your camera to “Tungsten”, and both I and the background will look neutral:
Done. Now we both look normal.
So, in summary: when you are dealing with a colour-cast ambient light, gel your flash to that same colour cast, and then adjust your white balance setting to that colour cast.
You can learn all about this, and much, much more, from my e-books. Now available from http://learning.photography — the checklist book even as a printed manual now,
I shot some demo product shots with my student Merav today, and I thought I would share them here to underline the importance of colour.
Here’s one, a simple one. Lit by a softbox on the leeft, an umbrella on the right, and against a grey backdrop. That gives us this:
Bit boring? Yes it is. So I add a gridded, “egg-yolk yellow” gelled speedlight aiming at the background. (I use the excellent Honl Photo grids, gels, and other small flash modifiers):
Much better. Then we added another light – a green-blue gelled speedlight shining in from the left:
Then we reversed the gel colours:
Then, tried another background colour, rose purple:
And finally got to a background coloured Just Blue, which had been Merav’s idea all along:
Which one did you prefer? Can you see how different they all are?
To shoot this I used this setup:
This works as follows:
- Put the bottle on a table, with white paper underneath
- Put up a grey backdrop, far from the bottle so it does not get any light
- Get the main lights right – use a light meter to set them to your desired values (I used f/9 and 1/125th second at 200 ISO). Main strobe is fired with Pocketwizard; secondary strobe by its cell.
- Add a background light: a small flash also fired by a Pocketwizard, through a Flashzebra cable. Set to 1.4 power. Equipped with a 1/4″ Honl grid and a gel.
- Add a side light: a small flash also fired by a Pocketwizard, through a Flashzebra cable. Set to 1/4 power. Equipped with a gel.
Simple. Once you know!
Why the rum? It was the only bottle I had in the house. Amazingly, for the first time I can remember, I had not a single bottle of beer or wine or anything else available in the house. Time to hit the liqor store!
“Saturation”, as I have pointed out here before, means “mixing with white light”. The higher you expose, the lower your saturation.
So a “normal” exposure of a phone box against an ochre yellow wall may look like this:
Fine. I guess.
Now do it again, but underexpose by a stop, and see how that brings out the colour:
Colour is an interesting thing. It can help or hinder your pictures. It helps if you are using it where it is wanted; it hinders if you use it when it is not, or if you fail to use it when it is.
The Caribbean is all about colour. People are happy, the sun is hot, and everyone uses wonderful bright colours. So a scene like Philipsburg, Sint Maarten, needs colour:
- Flash: I needed to use my Canon 580EX flash for this sign.
- Exposure: I made the colours vibrant by exposing the rest of the image down a little: 1/200th at f/13 at 100 ISO.
In the following image, I needed no flash – or rather, it would not have done anything:
In the next example, I needed the flash just to light the plants that make up the roof, or they would have been black:
And one more, where I used the flash:
One more – a street grab:
And one more, again showing wonderful Caribbean colour:
I suppose this all boils down to a few simple rules:
- Decide if color is needed; is it an important part of the image?
- If so, expose well – underexposing ever so slightly will make colours more. saturated; overexposing leads to washing out. (Note: you are allowed to “expose to the right and fix in post – you get better quality).
- Use a flash if needed to light up areas that need lighting up.
- Use the right white balance.
- Consider a polarizer on sunny days.
- Add a little saturation in post if you have to.
All very logical once you think about it.
Each light type has its own colour temperature (the redness or blueness of the light, where redder is “warmer”, and more blue is “colder”, in photographers’ terms). This colour is expressed as a temperature, which is measured in degrees Kelvin (after Lord Kelvin). Physicists and engineers know this.
Our cameras need to adjust to the light’s colour temperature. In the film days we used to do this by selecting the right film, which is sensitive to match the colour temperature of the light used (Tungsten film for incandecsent light bulbs, daylight film for daylight).
On digital cameras we use the White Balance setting. Set it to “Tungsten”, “Fluorescent”, and so on. Or we can set it ourselves, and that is today’s tip of the day.
On many cameras you have a “K” setting. You can now adjust the white balance by setting it to the colour temperature of the light used:
- Blue sky: 10,000K
- Shade from blue sky: 7,500K
- Daylight shade: 6,600K
- Summer daylight: 5,500K
- Flash: 5,500K
- Mid afternoon daylight: 4,500
- Evening sunlight: 3,500K
- Tungsten light: 3,200K
- Sunset 2,500K
- Candle light: 1,600K
So setting those white balances makes light look white. Is that what you want? Then set that white balance to match the light. That is the simple method: to get white to look white, select the colour temperature of the light illuminating your subject. And by using the Kelvin scale, you can make this pretty exact. So if a light is too red for you, adjust K until you are happy.
But there is another method: If you do not want white, then set the white balance to a different value from the value of the light hitting your subject. I.e. you can shift white balance. So if I set my white balance to 5,500 on a sunset evening, I get not white, but red – which presumably is exactly what I want for a sunset.
Yes, you can do this on your computer if you shoot RAW, but I still recommend getting it right in camera.
And that was today’s tip!