Photography- Exposure :precautions to be taken in full auto-mode
Most people use their camera in fully automatic mode for their photos. If for some settings such as white balance, it works well, there are some precautions that must be taken for the other settings.
Medium Grey and Exposure Value
Medium gray
The Medium gray is a particular gray with a reflectance of 18%. That is to say, it reflects back 18% of the incident light.
Basically, a reflectance of 18% is the favorite of the human eye: This is why most cameras are based on the medium gray to calculate the exposure photos.
Exposure value
The exposure value, is a system to measure the relative brightness of a photo. A photo taken in the standard condition, that is to say, without exposure compensation, will no EV (EV = 0).
You can then increase or decrease the EV by playing on three exposure settings (sensitivity, aperture, exposure time).
In some cases it will be necessary to increase or decrease the EV to get a realistic exposure...
Precautions to be taken with th medium gray
Even if the picture produced using medium gray are fun to watch, they are sometimes far from reality. Indeed, consider these two examples:
- If one performs a measurement spot on the white part, we realize that black is black, but white is gray.
- If one performs a measurement spot on the black part, we realize that white is white, but black is gray.
Similarly, if you take a picture of a street scene at night, the camera will overexpose and the picture will be as clear as in daylight ..
What can be done
It's simple: use the exposure compensation feature on your device.
- If your subject is medium gray: no correction.
- If your subject is lighter than medium gray: overexpose a little or a lot depending on the result you want to achieve.
- If your subject is darker than medium gray: underexpose a little or a lot depending on the result you want to achieve.
See also
Knowledge communities.
Original article published by
Mihawk. Translated by
jak58.
