This is a common question from novice photographers expecting a simple set of instructions to solve a complex and highly variable exposure problems.
There is no right answer, each situation is a unique a blend of light and movement that challenges advanced photographers. This is the reason for the number of exposure adjustments in digital cameras.
The complexity is confusing leaving aspiring photographers with little idea where to start, particularly as the camera’s exposure settings are related, so altering one affects the others.
Practice is always a valuable learning experience, but it needs a clear plan. These exposure setting recommendations are for daylight for stationary or slow moving subjects.
Aperture
This is the F-stop thing. This is how wide the opening is in the lens that controls the amount of light going into the camera. Confusingly the lower the f number the wider the lens opening.
Low f numbers mean less of the photo is in focus and lens distortion increases for most lenses at these aperture settings.
A good general setting is around f 7. This lets in enough light during the day.
At night or inside a building a smaller f number may be required.
Shutter Speed
This works in conjunction with the aperture to control the light entering the camera. In low light the shutter needs to be open longer to allow in enough light for a properly exposed photograph.
There are other things shutter speed does to photographs. Using a slow shutter speed, or keeping the shutter open longer, causes blurriness for moving subjects or blurriness because the photographer could not hold the camera ready.
For most situations a shutter speed of 1/125 of a second allows a reasonable amount of light yet is short enough to produce sharp images.
For sports, particularly with longer telephoto focal lengths, faster shutter speeds are used.
ISO
This is the sensitivity of the digital sensor to light. In dim light using a higher ISO setting allows the camera to work without adjusting the aperture or shutter speed.
Of course there is a catch. Digital cameras work best at their lowest ISO settings. Higher ISO settings introduce more digital noise, reduces dynamic range and colour sensitivity.
The actual number varies between different camera models, but the principal is to set the ISO at the lowest possible setting.
Digital cameras normally have an Auto ISO setting where the camera sets the ISO, and they are programmed to use the lowest ISO for each photo, they only raise the ISO when needed.
Auto ISO is the best setting
Aperture Priority Camera Exposure Mode
For general photography the semi automatic Aperture Priority exposure mode is best. Photographers select the aperture best for their lens and good focus. The camera adjusts the shutter speed, along with the ISO, for correct exposure. The camera tries to keep the shutter speed short enough to minimise any blur.
Starting Point
These settings provide a good starting point for photographers to start taking control of their camera and experimenting, yet still achieving reasonable pictures.
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