Most cameras will show you the settings you are or have used when taking pictures.
You can check what aperture (“f-stop”), speed and iso are in use in the viewfinder, live view or image metadata.
The follows examples are to help explain in pictures what effect these three controls have.
For this example you need a picture that has three or four subjects at different distances away, such as items with a garden. The idea is to vary the depth of field varying where the focus point is with different aperture settings. It is best carried out using a tripod to ensure consistency.
1 Take a control picture using full Auto and write down the settings the camera used. The camera should be focused on the nearest object.
2 Now using Manual mode change the camera to these settings and take it again. It should look the same. Depending on the camera, you may need to explicitly set manual focus. In any case, leave the focus position on the nearest object.
Now do steps 3, 4 and 5 and write down the settings after each. Keep the focus on the nearest object.
3 Start with the widest aperture that your lens is capable of (e.g. f 2) and take a picture. The idea is that only the nearest object will be in focus.
4 Change the aperture by stopping down about two f-stops, (e.g. to f 4) and take a picture. where second item is also in focus. Use more than two f-stops change if necessary.
5 Now change the aperture to its smallest sett (e.g. to f 16) and take another picture. Hopefully, the whole range of subjects will now be in focus.
Record your settings in the table below
FSTOP SPEED ISO