Correction Filters In Use On Flash Units

Polarizing filter, neutral density filter, Skylight filter protector know almost all Fotoenthusiansten. With color filters for black and white photography are thinning the ranks of the experts, however, already. Color Correction Filter for lenses are all but forgotten, as the camera's internal white balance these unnecessary in most cases makes. That there is correction filters for flash units and how they are used, only a few know. We want to define this photo tip the basic handling of these films and show that it is not a work of the devil, but a tool for creative photography.

The use of correction filters, short correction sheets for Flash comes from the time of the analog color photography and is necessary if a photographer had to work with mixed lighting. In times of the auto white balance and image processing on the computer seems this effort in the shooting to be no longer necessary, but that's a mistake. Not everything has to be corrected easily via image processing on the computer. In previous photo tips was to highlight the flash technique a little more detail (see related links) and have the topic correction film also briefly touched upon.

Correction film called CTO (Color Temperature Orange) and CTB (Color Temperature Blue) and they come in different strengths. Put simply, does the CTO that emitted light "warmer" and the CTB makes the light "cool". The correction films are available in different sizes. Sometimes the flash device manufacturer provides suitable foils also as accessories or supplies that even with the flash. Since high-quality filters are relatively resistant to heat, they can be installed at a small distance on the flash. The assembly of the sheets can be effected in various ways. So you can rely on easily removable tape or velcro to stick to items on the slides and flash. Another possibility is the rubberized Honl Speed ​​Strap with its large Velcro. The Speed ​​Strap has the advantage that it can be removed at any time by the flash and just under ten euro is a real bargain. To assemble a slide to the Speed ​​Strap, you can now rely on self-assembled films or one invests just under 30 euros in a filter set of the Honl Speed ​​Strap manufacturer.

Usually used to correction filter if you want to combine Flash with another light. The color temperature of a flash is just under 5600 degrees Kelvin, which is about the color temperature of the indirect midday sun. If you want to shoot now an object in an environment illuminated by light bulbs, then the light emitted by the flash is not suitable for the ambient light. Here must be aided by a correction film. To the camera white balance is set to the default light bulbs or using manual white balance to the light color. Then mounted to a CTO correction sheet on the flash unit. Here, you must now determine a test shot that film strength of the correction is the right to receive such a color-balanced image.

The sample image on the left would, despite sufficient daylight, of a correction film benefited greatly on a flash. In the background is an irradiated field of the setting sun, on which the camera has set the white balance. The model was put in the shade to get a soft illumination. In principle a very good idea, but is not to use the picture as the color temperature difference from the background (around 2,300 degrees Kelvin) to the model in the shade (about 7,600 degrees Kelvin) is too large. It shows the model's face a cold color, while the background has the desired color look. Had the camera decided otherwise and used her face as white balance reference, then the background would become too hot and would have made the picture again unusable. The error could have been avoided by using a Zebra reflector to supply the face and matching light (see picture right). Disadvantage of such a reflector is that exist on the one reflektierbares light near, and that the strong reflection characteristics, the model gets in trouble, keep your eyes open to uninhibited. The best way to use a flash with a CTO correction film would have to match the color of the face of the model and at the same time not destroy the character of the background color.

But what would happen if the white balance is intentionally wrong to create a certain atmosphere? In our next example we want to do a portrait in the blue hour. To the blue hour to make a little blue, we set the white balance manually to a low value. Does the camera have no input for a color temperature value, so you can work with the existing cameras in all presets. In this example, the setting for incandescent lighting would be appropriate. If the white balance is set, a correction CTO film is mounted on the flash unit. After the flash unit is attached or placed so that it can be triggered wirelessly. Then adjusted the model to pose, and the flash is possible direction yet. Then you shoot his first test recording and analyzes:

If the background is too dark, then the exposure time increases (Warning possible camera shake).
If the background is too bright, then the exposure time can be shortened.

Then you look at the flash color:

If the flash color to "warm", then you have a lower CTO filter foil can be used. Already is the lowest level reached, then you can try to flash without correction film. Is this also not crowned with success, the white balance of the camera a little "up" can be adjusted.

If the flash color to "cold", then you have a stronger CTO filter foil can be used. CTO is the highest filter film has already been used, then a further CTO filters are mounted on this film.

If the picture is just as you would imagine, you can feel free to work with these settings. If other flash units are used, you can equip them with color filters to create special effects. Here then the sky is the limit. These pure color filter films are mainly used only as an effect and can not be used for the neutralization of colors.