Getting Off Full Auto - Looking at it a Different Way
As you are aware there are 3 main camera settings which influence the photographs we take:
I
SO,
Aperture, and
Shutter Speed
The aperture triangle illustrates how these 3 settings interact with each other.
Looking at it a Different Way
The aperture triangle is displayed in an alternative format in the table below which lists valid combinations of the 3 for a single scene on a bright sunny day. You do not have to remember this or even use it as a look up because the camera does all that for you. (This is an abbreviated list and only includes full stop intervals, most cameras allow 1/3rd increments). Each combination will give a well exposed image and each image will have a different artistic characteristic.
Exposure Value Table
Taking photos on full auto gives the camera responsibility for selecting which of these combinations to use. While modern cameras have sophisticated ways to analyse the scene in front of them they do not know your artistic intent. That is why there are so many (mainly unused) alternative automatic settings which the user could use to communicate that intent but they are rarely used because they are so difficult to work through. It is easier to take control of the camera yourself by fixing one or two of the settings that define what you want in the final image and allow the camera to calculate the rest.
This final table summarises the characteristics of each of the settings and when you might use them.
In Summary
ISO
ISO is a measure of how sensitive your camera is. High ISO values reduce the quality of your image but enable you to shoot hand held in low light situations.
Aperture
Aperture controls depth of field in your image (as do lens focal length and sensor size).
Shutter Speed
The length of time the shutter is open dicates the impact of movement in your image. Fast shutters freeze movement, slow shutters blur movement.
Recommendation
In practice, I recommend you start off with 1 of the 2 semi automatic shooting modes on your camera:
Examine the scene and decide how you want Depth of Field and Movement to be portrayed in your image and their relative importance.
This will give you an idea whether to use Shutter Priority or Aperture Priority.
Set ISO to Auto Select,
Select either Aperture Priority, or Shutter priority
Adjust ISO if the final result is not what you want.
Next Steps
We have not yet considered how your camera interprets the data from the sensor and post processes that information to create a jpeg image as this also has an impact on the artistic result. We will consider this another day.