While conducting photography workshops for some years now I have realized that many photographers in the country have not understood the importance of white balance settings, neither have they known how to set the same in their digital cameras. I recently held workshops on studio lighting at many places outside Mumbai. After imparting some training on lighting if I would ask for the queries on lighting I would receive the same on white balance instead. Photographers though carry expensive SLR-like or DSLR cameras of the well-known brands such as Nikon, Canon, Fuji etc seem to be not happy with the resulting outputs in general and with the colours in particular. Of course they themselves have to be blamed for getting poor results. So friends let us try to understand what White Balance is and how to achieve it correctly.
White balance may be defined as “setting the colour sensitivity of the image sensor depending upon the colour composition of light to get a truly white object rendered as white in final output”.
The light which we generally use for taking photos-may also be called as General Illumination-contains the three primary colours Red, Green and Blue. The proportions of these three colours may not be the same in any given illumination. If the light contains all the three colours in equal proportions then the light is said to be pure white and believe me pure white light rarely exists in reality. For instance a morning or evening sunlight contains more red than blue with green in between(see figure 1), hence looks yellow, whereas at noon in summer it contains more blue than red(figure 2). As the sun rises up in the sky the proportions keep changing, red becoming lesser and lesser with blue progressively increasing its proportion till mid-day. Average sunlight at around 10 a.m. in summer is said to be close to white(figure 4). A photographer should know that a tungsten lamp is more yellow(figure 3) than average sunlight and domestic tungsten lamps deliver more yellowness than the photographic tungsten lamps such as photo floods and halogen tubes. An electronic flash is assumed to yield white light close to average sunlight.
Early morning at sunrise and evening at sunset the sunlight looks yellow but otherwise it seems to be white all the time during the day even though it is not so. Sunlight through clouds and that under open shade (skylight) though looks white, is little blue in colour. As mentioned earlier the tungsten lighting is yellow. An object in fact picks the colour of the incident light hence a white object does not remain white if the incident light is not white. Despite the light is not white various objects or scenes seem to look natural in colouring to our eyes. In other words our eyes fail to detect the exact colours of the objects and tend to see everything as normal in colouring. Why does this happen so, why our eyes fail to detect the true colours? Obviously for two reasons, firstly our eyes are subjectively controlled by our mind; we see what we expect to se. If we already know that an object is white we tend to see it as white only. White is taken as a reference colour here. The same is true for all other colours. Secondly our eyes have a remarkable power of adaption, theyadapt or adjust their colour sensitivity depending upon the colour of illumination so that a white object still looks white even though it is not so. This is similar to Automatic White Balance setting in Digital Camera. A camera neither has a mind nor has the ability to adjust colour sensitivity (unless it is set to Auto White Balance settings); hence on many occasions renders unsought colours on the final output, what you think you saw at the time of exposure may not be the same as what you get on your final photograph in colouring. The problem may be resolved by choosing the right type of film, using appropriate colour filters, adjusting the colours later during printing in case of film based photography and making colour correction on a computer using editing software or most importantly setting accurate white balance in case of digital imaging.
Digital cameras have three types of white balance settings, Automatic White Balance (AWB) setting, Preset Manual settings and Custom White Balance setting. If a camera is set to AWB settings, it “measures” the colour composition of light and sets the colour sensitivities of the image sensor accordingly. As the morning sunlight and tungsten lighting is yellow, the camera increases the sensitivity to blue. (I hope you must be aware that blue is a complimentary/opposite colour of yellow). Whereas in shade, as the light is little blue, it reduces the sensitivity of blue. This works exactly similar to our eyes. AWB should be recommended in ambient light for instance outdoors during the day or indoors in available ambient light (remember you will not be using flash). In an outdoor situation sunlight keeps changing its colour from morning to evening and AWB setting can cope with such changes. Custom WB or Preset Manual settings on the other hand can’t cope with such changes because they are set for specific colour of light. The colour composition/colour of light should also be uniform. AWB though works well under mixed lighting situations may also fail to deliver good results indoors sometimes. Imagine a wedding hall interior illuminated with different lightings such as halogen lamps, CFL, incandescent domestic lamps, video light etc. AWB will work satisfactorily if the light is uniform at a particular place where the photograph is shot, for instance a video light thrown on the wedding couple. But if the highlights are lit up by a weak video light and the shadows are filled in by CFL or other type of lamp then you will get a colour imbalance on the subject. Avoid such situations and try to get uniform lighting all over the subject. AWB is also fooled sometimes if a particular colour dominates the scene for instance a red coloured backdrop behind the wedding couple. A word of caution here, please check the colour temperature range for AWB for your camera, which is shown in the camera manual. For instance Canon 350D sets AWB within the range of 3000K to 7000K.If the Colour Temperature of the light falls outside the range, the camera will not set WB correctly. Colour temperatures of different light sources are given in this article for your reference. (And to understand what Colour Temperature is, please refer to Questions and Answers section on the page Ask Guru of this site).
Digital Cameras have many preset Manual settings for specific light sources and they are generally denoted by different icons such as Direct Sunlight, Cloudy Sunlight, Skylight or Shade, Tungsten or Incandescent, Fluorescent, Flash and Colour Temperature etc. You may select any one of them depending on the light source you are shooting in. Setting WB on Sunlight is like shooting on a Daylight balanced film. This setting would give reasonably good results if you are not shooting early in the morning, late in the afternoon or around Mid-Day under sunlight.Sunlight through clouds is little blue and that under open shade is still bluer. Tungsten setting would be good for shooting under halogen tubes; it is like shooting on a Tungsten balance film. I have observed that different camera brands define Tungsten light differently. Some manufacturers set white balance for 3200K whereas some set it for 3400K for their Tungsten setting. Domestic incandescent lamps deliver more yellowness hence a Custom WB would be preferable. Even AWB setting in some cameras may not cope with such yellowness in the light and the resulting photos still show some yellow cast.
A preset manual setting for Flash is only good with a flash made by the same camera manufacturer. The colour temperatures of flash may vary from brands to brands, for instance Canon set the colour temperature for their flashes to 6000K whereas Nikon set it to 5400K. If you are using the same manufacturer’s flash then it’s ok to select Flash WB. Avoid selecting Flash white balance for studio flashes; Custom WB would be preferable in this situation.
Accurate white balance can be set for a particular light source or mixture of different sources using the Custom White Balance setting. If you are shooting under a lighting that is not likely to change, then there is no better option than a Custom White Balance setting. Shooting in a studio with studio flashes, using a third party flash in a function like wedding or shooting under uniform ambient lighting indoors are some of the examples where Custom WB should be preferred. Never use AWB settings under studio flash lighting. White balance reference can be taken from a truly neutral target card like a truly white sheet or an 18% gray card. (18% Gray cards are now rarely available for sale). A Thermo Cole sheet though not pure white may give consistent results. Follow the procedure for setting Custom WB as mentioned in the camera’s instruction manual. Though the procedures differ from camera to camera the basic principles are the same.
Certain factors are very important while setting Custom WB. Firstly the target card must be a neutral flat surface like a white sheet or a Gray card. Secondly the target card must be illuminated by the same light source that will be used for shooting. Thirdly the camera must be pointed to the card so as to cover the card only. And lastly but more importantly as you are going to shoot the card, the exposure must be set accurately. In most of the cameras the card is not actually captured and saved on the media but it is shot and saved on the media if you are using Canon EOS models. Let us now discuss about procedures adopted by different camera makers.
Fuji Fine Pix 7000, 9500 or 9600 camera:
Shooting under ambient light:
If you are shooting under ambient (continuous) lighting, set the exposure mode to either A or S or P. Hold the target card at the same place as the subject and cover it fully in the viewfinder. It’s not necessary to focus the target card. Illuminate the card, select Custom WB from the Menu and press shutter button. Now the display will show Completed, press OK and proceed. If the display shows Under, increase the exposure by selecting a smaller F number or a slower shutter speed and if it showsOverthen decrease the exposure by selecting larger F number or a faster shutter speed and follow the same procedure again till the display shows Completed. Remember the white balance can not be set correctly unless the display shows Completed.
Shooting in a studio:
Custom WB can also be set for studio flashes as discussed under.
Hold the Target Gray card at the same place where the subject would sit in a studio. It is important to hold the card at this place only, because it will then only measure the light that will actually fall on the subject. The light that reaches the subject may get affected by neighboring colours such as the colours of wall, the backdrop or any such object that can have impact on the colour of light reaching the subject. A strong coloured background always shows its effect on the subject so if possible it’s always better to have sufficient distance-may be 5 to 6 feet- between the background and the subject in a studio set up. Set the correct exposure using manual setting (selecting M on the mode dial) as you would set it for the subject and follow the same procedure as discussed above. The shutter speed should be set within the range of 60 to 250. Follow the same procedure as mentioned above if the display shows either Under or Over, but this time you should change only the aperture keeping the shutter speed unchanged. A white sheet (or even a thermo cole sheet) may also be used as a target card, but the aperture should be reduced by 2 stops temporarily while setting the WB since it reflects more light resulting over exposure. Open the aperture now for taking the actual shots of the subjects after the WB operation is completed. (For instance the final aperture for your subject is say f5.6, then for measuring WB change the aperture to f11 and after the WB is set correctly bring the aperture back to f5.6). These SLR-like Fuji cameras have minimum apertures of either f8 or f11. Even after setting the minimum aperture for setting Custom WB, the white target card gets over exposed and the camera doesn’t allow you to proceed. Use an ND filter or take the studio flash light more away from the card and try again.
Shooting with portable Auto flash:
If you are using an Automatic Portable flash like the Vivitar 285 or Metz 45 CL-1 that is set on auto mode, then you need not close the aperture, even if the target card is white, set the same aperture for setting WB as you would set finally for shooting, set shutter speed in the range of 60 to 500. Follow the procedure as mentioned above.
Select Preset White Balance from MENU (Nikon call custiom white balance as Preset WB). This can also be done alternatively by pressing the WB button located at the left side of LCD monitor and turning the command dial. Set the exposure mode to either A or S or P. Hold the target card at the same place as the subject and cover it fully in the viewfinder. It’s not necessary to focus the target card. Now keep pressing the WB button till PrE starts flashing on the LCD panel(see figure 5). Illuminate the card and press shutter button. Now Good will appear on the LCD panel(figure 6) to indicate the completion of the process. Press shutter button halfway and start taking pictures. In case no Gd flashes on the LCD panel(figure 7), check the exposure settings, it may be either under or over exposed, make necessary corrections and try again.
Custom WB can also be set for studio flashes as discussed under.
A similar procedure may be adopted as discussed above for Fuji cameras, the only difference is that unlike Fuji cameras, Nikon models will not tell you whether the target card is under or over exposed. Set mode dial to M, set synchro speed on camera and follow the procedure mentioned above for setting WB in Nikon cameras. Good appears on the LCD panel if the card is exposed correctly, otherwise the panel shows no Gdindication, so it’s now your responsibility to set correct exposure. Exposure now can be changed only by changing aperture and not the synchro speed. If thermo cole sheet is used as a target card do not forget to close down the aperture temporarily by 2 stops for setting WB. For instance, if correct exposure for the subject is achieved at say f8 then set f16 (double the f number) while setting WB, after setting WB successfully bring the aperture back to f8. No need to close down aperture if a gray card is used.
Shooting with portable Auto/TTL flash:
If you are using an auto flash such as Vivitar 285 or Metz 45 CL-1 set on Auto mode or a Dedicated TTL flash like Nikon SB600 or SB800 set on TTL mode then set the mode dial to M, set synchro speed and the same aperture you would be setting for taking pictures regardless of whether you use a gray card or a thermo cole sheet for setting WB. Follow the procedure for setting Preset WB as described above for Nikon cameras. You would get Good indication on the LCD panel if the aperture is not too small.
Canon DSLR cameras 350D, 400D, 30D etc.
Shooting under ambient light:
You actually shoot a target card to set custom WB in Canon DSLR cameras and the same is saved on the media for future WB settings. Set exposure Mode Dial to either Av or Tv or P. Cover the target card and shoot. The camera won’t tell you whether the card is correctly exposed or not, you have to check that using histogram info. Press the Playback button and check the histogram. It should look like the one shown in the figure 8. The target card is under exposed if the histogram is too much on the left side(figure 9), spread in the left half of the diagram and if it touches the extreme right side(figure 10) then it is overexposed. The info also gives overexposure warning with flashing black colour on the image of target card. Try to achieve correct exposure with histogram as shown in the figure 8. As the mode dial is set to either Av or Tv or P you generally get correct exposures. Once this is done you may now set the Custom WB by operating Menus. Go to Custom WB sub menu, press SET, browse the image you have just shot, ( it automatically appears on the screen if that is the last image shot), press SET. That’s it.
Now select Custom WB by operating White Balance sub menu and start taking pictures.
Shooting in a studio:
A similar procedure should be followed as discussed above for Fuji and Nikon cameras. Achieving correct exposure is now your responsibility since the camera neither indicates under nor over exposures. Set mode dial to M, set synchro speed and shoot a target card setting some aperture. Check the histogram of the target card’s image and try to achieve correct exposure by shooting the card repeatedly. You need to close down the aperture by 2 stops if WB is set using thermo cole sheet.
Figure 8 Figure 9
Figure 10
Once the proper exposure is achieved follow the procedure of setting WB as discussed above for Canon cameras.
Shooting with portable Auto/TTL flash:
If you are shooting with an Auto flash set on auto mode or a TTL flash such as Canon 430EX or 580EX set on TTL mode, then set mode dial of camera on M, set synchro speed, set the same aperture you would do for taking pictures and shoot the target card. Check the histogram of this image, make necessary corrections in exposure settings if need be (you would generally get correct exposures with such flashes) and shoot the card again. Once correct exposure is arrived at, follow the same procedure for setting Custom WB.
