2. Most digital cameras support a number of digital
camera modes for use in various situations.
Professional DSLR cameras modes focus more on manual
modes, consumer point-and-shoot cameras focus on automatic
modes, and amateur prosumer cameras often have a wide variety
of both manual and automatic modes.
Manual-enabled modes give the photographer control over the
various parameters of an exposure. There are three exposure
parameters – aperture, time (shutter speed), and sensitivity
(ISO), and in different modes these are each set automatically or
manually; this gives 23 = 8 possible modes. For a given
exposure, this is an underdetermined system, as there are 3
inputs but only 1 output. Accordingly, there are many
combinations that result in the same exposure – for example,
decreasing the aperture by one stop but increasing the exposure
time or sensitivity to compensate, and there are various possible
algorithms to automatically choose between these.
Most often, ISO is considered separately, being either set
manually or set to Auto ISO, and then only aperture and shutter
speed need be determined – either determines the other.
The four main modes, sometimes abbreviated "PASM", are:
P: Program mode has the camera calculate both shutter speed
and aperture (given a manually or automatically selected
ISO). Higher-end cameras offer partial manual control to
shift away from the automatically calculated values
(increasing aperture and decreasing shutter time or
conversely). The difference between Program mode and Full
Auto mode is that in program mode, only the exposure is
automatic, while other camera settings (e.g., shooting mode,
exposure compensation, flash) can be set manually; in Full
Auto mode everything is automatic.
A or Av: Aperture priority or 'Aperture value' enables manual
control of the aperture, and shutter speed is calculated by the
camera for proper exposure (given an ISO sensitivity).
3. S or Tv: Shutter priority or 'Time value' enables manual
control of the shutter speed, and aperture is calculated by the
camera for proper exposure (given an ISO sensitivity).
M: Manual mode both shutter speed and aperture and
independently set manually (with ISO sensitivity also set
manually), where proper image exposure requires accurate
manual adjustment.
Together with setting ISO manually or automatically, this yields
the 4×2 = 8 possible combinations of manual/auto.
Common camera modes
Shutter mode Aperture mode
Program mode
Manual mode
Automatic mode
4. Auto/Program Camera Modes:
Icons Description
Auto The camera will completely control flash and
exposure. On most cameras this is labelled "auto", on others
simply "A". Some cameras only have (P)rogram.
Program automatic-assist, just point and shoot. Unlike
full auto mode, you can usually control flash and a few other
camera settings.
Aperture Priority Photographer sets the aperture
(f-stop) and the camera will attempt to deliver a good exposure.
Some cameras use an "A" icon instead of "Av"
Shutter Priority Photographer sets the shutter, and
the camera will attempt to deliver a good exposure. Some
cameras use an "S" icon instead of "Tv"
Manual Full manual mode, the photographer must set
both the shutter and the aperture mode.
Photographs by different camera modes
This photograph captured by Aperture mode