Flash photography is fundamentally not the same as shooting available light, which can be likely beyond your control: your flash, which you have some control over, and a standard camera exposure since two light sources are lighting your subject. In this portion of the tutorial we’ll concentrate on both of the other consequences of this fact, as they pertain to flash exposure.
Each type of flash control has clear benefits and disadvantages. When ambient exposure and both flash output changes, the flash ratio can be certainly adjusted by one without changing the overall exposure; a 1 FEC and – 1 EC setting will leave the overall exposure unchanged, for example. When only surrounding exposure changes, FEC and EC effectively become independent managements but these cameras also can make it harder to work with FEC and EC without also altering the general exposure to shift the flash ratio. The balance of the section targets using all these settings to control the flash ratio, if you just chance to possess this sort of camera.
Flash ratios of greater or 1:2 are where the topics in the first half of this tutorial become important, including its light place that is apparent and the flash position, since the flash can seem rather harsh unless carefully controlled. For this reason, most photographers will likely wish to use their flash as a fill flash, if possible, since this is actually the easiest kind of flash photography.
One of the hardest endeavors in flash photography is understanding how different camera and flash metering modes will change a complete exposure. Some modes assume you only want a fill flash, while others effectively ignore ambient light and suppose that your camera’s flash would function as the dominant source of illumination.
Luckily, all cameras use their flash as a fill flash the main light source or as either. The key is understanding when and why your camera uses its flash in all the manners. A table summarizing the most typical camera ways is recorded below:
The flash ratio then increases progressively as light reaching the subject gets dimmer, but the shutter speed remains at 1/60 of a second.
The key is knowing just how to get the desired mix between light from ambient sources and light — while also getting the correct amount of light that is complete (from all sources) to achieve a properly exposed image.
The “flash ratio” can be an important method to describe the combination between ambient light and light from your flash. Since the shutter speed does not affect the level of light shot from your flash (but does affect ambient light), it is possible to use this fact to restrain the flash ratio. To get confirmed amount of ambient light, flash and ambient light’s mix is corrected using only two camera settings: (i) the period of the exposure and (ii) the flash strength.
The flash ratio* is used to characterize the ratio between light from your flash and ambient light. At one extreme of the ratio is ordinary ambient light photography (left), and in another extreme is photography using mostly light from the flash (right). Practically though, there is always some number of ambient light, so an endless flash ratio is a theoretical limit.
*Technical Note: Sometimes the flash ratio is rather described concerning the ratio between absolute light and light in the flash. A 2:1 if so, 3:1 and 5:1 ratio would be equal to 1:2 a 1:1 and 1:4 ratio in the table above, respectively. Sadly both conventions are used.
It is very important to additionally note that not all flash ratios are necessarily attainable with a given flash unit or surrounding light intensity. If surrounding light is not extremely mild, or in case your flash is far out of your issue, it’s improbable that a compact camera’s internal flash could reach flash ratios approaching 10:1, for example.
Program (P) mode resembles Auto, except one can additionally induce a flash to be used in scenarios where the subject is well-lit, by which case the flash will become a fill flash. The fill flash ratio may thus be anywhere from 1:1 (in dimmed light) to 1:4 (in bright light).
Nevertheless, unlike with Automobile and P modes, the flash ratio never grows beyond about 1:1 and exposures are as long as crucial (aka “slow sync”). In Television mode, the flash ratio may also rise if the f stop that is essential is smaller than available with your lens.
In Manual (M) mode, the camera exhibits ambient light based on how you set the aperture, shutter speed and ISO. Manual mode therefore empowers a substantially more comprehensive range of flash ratios in relation to the other modes.
In all modes, the applicable setting in your viewfinder will blink if there is a flash exposure not possible using that setting.
The best technique for altering the flash ratio is utilizing the right combination of flash exposure compensation (FEC) and average exposure compensation (EC). FEC works much like regular EC: it tells the camera to take whatever flash intensity it was planning to use, and also to override that from the FEC setting. The big difference is that while EC may affect the exposures and ambient light (depending on camera model), brassy intensity only affects.
Both EC and FEC are defined regarding stops of light. Each negative or favorable stop identifies a doubling or halving of light. Hence a 1 EC or FEC value means a doubling of light, whereas a -2 value means there is a quarter as much light.
With present Canon cameras, EC exclusively changes ambient exposure, whereas with most Nikon cameras, EC concurrently changes ambient exposure and flash intensity. A few of the more recent Nikon cameras, including D800 and the D4, can work either way via a custom function.