Basic DSLR Functions
'Av' Mode
'Av' stands for "Aperture Value" which allows the user to select the f-stop (aperture) of the lens with the camera then selecting the
corresponding shutter speed. A small f-stop actually opens the lens wider and a large f-stop closes the lens.
The quality of the lens will dictate the f-stops that can be used, the better the lens the lower the f-stop. If the f-stop is set at the
lowest possible setting for the lens this will give a shallow depth of field resulting in the object being in focus and the background blurred. If the f-stop is set
higher this will give a deeper focus resulting in more of the image in focus.
The area within the depth of field appears sharp, while the areas in front of and
beyond the depth of field appear blurry. (Wikimedia Commons)
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| At f/32, the background competes for the viewer’s attention. (Wikipedia) |
At f/5.6, the flowers are isolated from the background. (Wikipedia) |
The larger the f-stop used the less light that is available to the camera, so it is important to monitor the shutter speed ensuring it isn't too slow to allow the camera to be hand held.
Different lenses behave in different ways so it is important to practice different settings with each lens so that you get used to its characteristics allowing you to obtain your desired effect.
'Tv' Mode
'Tv' stands for "Time Value" which allows the user to set the shutter speed with the camera selecting the appropriate f-stop for correct exposure.
This is the best mode to select for photgraphing 'action' shots when you need to keep the shutter speed high. When taking photographs of airborne aircraft, jets should be
photographed around 1/1000th of a second shutter speed and propeller aircraft around 1/320th of a second to show 'prop blur'.
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| Red Arrow photograph taken at 1/1000 of a second to obtain a sharp image. |
Spitfire photograph taken at 1/320th
of a second to show 'Prop Blur'. |
If conditions are overcast and you can't achieve a very high 'Shutter Speed' then increase the 'ISO speed'. It is also a good idea to make sure the aircraft fills the frame so that the aircraft is well exposed and uses maximum resolution of the sensor.
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R.I.A.T. 2019
