Flash Brightness
You can control the intensity of a flash-fill effect with a camera adjustment (This may be set differently on different cameras). Hold the bolt button (often by the flash) and the +/– button, (often next to the shutter release), simultaneously. Then, spin the rear dial until you see + or – numbers in the finder. The flash is brighter at the plus-number settings and darker at the minus-number settings. You’ll want to shoot some test images at the various settings to understand which are right for various photographic conditions.
Background Brightness
It’s not unusual to use a flash indoors and discover that the backgrounds have gone to black. The flash simply doesn’t have the power to illuminate the background. As mentioned in Part 2, shutter speed doesn’t directly affect the flash; it only adjusts for the ambient light of the background. To bring your backgrounds “into the light,” simply use longer shutter speeds. Of course, most cameras automatically set the shutter speed, so you must make several adjustments to bypass your camera’s brain.
Most cameras won’t automatically select a sync setting lower than 1/60th. At that speed, most movement can be stopped (no blurring), but indoor backgrounds go black. The solution is to set your camera to slow sync. Now your camera will allow slower shutter speeds that sync with your flash, and capture more of the light from the background, thus revealing it. (Refer to your camera’s manual for how to set slow sync.)
Solving one problem, however, leads to another. Whenever you’re shooting in very low light, very slow shutter speeds are required (the lens is open for a greater amount of time), which leads to blurry images. The alternative solutions are to set the ISO to a higher speed or to use a more reasonable shutter speed, such as 1/8th of a second. Another help is that you may own one of many camera brands that have the capability to set the slowest sync speed in their menus. Once you do, the camera selects all exposure settings automatically, but according to your criteria. Another solution is to lock the shutter speed manually or shoot in shutter-priority (S or Tv) mode. You’ll be prepared for virtually every type of shooting condition, from sunlight to indoor light, by setting the slowest sync speed to approximately 1/8th, and then shoot in program mode.
ISO Settings
ISO, of course, is another part of the equation. For most daylight digital photography, you can set your ISO to auto. Be aware, however, that ISO remains at its minimum as soon as you turn on the flash unit. Indoors, you must set a higher ISO manually, so shutter speeds remain in that “reasonable” range. Today’s cameras have extremely high ISO numbers to help expose pictures correctly under very low light. Remember, the primary consideration is for the flash output to match the ambient light; and, when it is very low, and the ISO leaps to a high number, the camera may be unable to make the match. There are only a limited number of f/stops over which the flash can provide a variety of correct outputs.
Gels can help you and your camera achieve that balance. For example, use a neutral-density (ND) gel, which is very dark. If you find yourself with an ISO setting of 1,600 or higher, you can match the flash-fill and ambient light by applying a full CTO + ND 0.6 gel to your flash face.
Be sure to look through the complete archive of how-to digital photography articles at PhotographyTalk.com.
Recommended Reading:
- Kevin Kubotas Lighting Notebook: 101 Lighting Styles and Setups for Digital Photographers
- Understanding Flash Photography: How to Shoot Great Photographs Using Electronic Flash
- Sketching Light: An Illustrated Tour of the Possibilities of Flash
- Off-Camera Flash Techniques for Digital Photographers
- Understanding Shutter Speed: Creative Action and Low-Light Photography Beyond 1/125 Second
- On-Camera Flash Techniques for Digital Wedding and Portrait Photography