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Depth of Field (DoF)
Depth of field can be manipulated to give different effects. With a shallow DoF (f2.0 for example) only part of your image will be sharp, whilst the rest will be blurred. By increasing the f-Number (see here for an explanation on Aperture) you can bring more of the shot into focus. The diagram below is a very simple representation of how the Aperture affects the DoF:
Not to scale
The purple circle represents you (the photographer) and the lilac oval is the object you are photographing. The red lines represent how much of the foreground/background is in focus depending on what Aperture is used.
Not to scale
The purple circle represents you (the photographer) and the lilac oval is the object you are photographing. The red lines represent how much of the foreground/background is in focus depending on what Aperture is used.
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Kit 1 Canon 20D Canon 28-135 3.5-5.6 IS USM Canon 70-300 4-5.6 IS USM Canon 100 2.8 USM Macro Canon 10-22mm 3.5-4.5 Canon 50mm 1.4 Canon 85mm 1.8 |
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My Compact/P&S: Canon Ixus V3 |
 Stealth Mod
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Join Date: Sep 2007
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Thanks for that explanation 
a lot easier to understand than the books.
a lot easier to understand than the books.
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Kit 1 Canon EOS400D Canon 60mm f/2.8 Macro USM Canon EF-S 18-55mm f/3.5-5.6 Canon EF-S 10-18mm |
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 Admin Team
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Thanks GH! Added to sticky!
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My Compact/P&S: Panasonic Lumix TZ7 |
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Join Date: Aug 2008
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The explanation is clear, but it fails to mention a couple of things.
1. Depth of field is also affected by a couple of other factors.
(i) The closer you are to an object, the narrower the depth of field gets.
(ii) The length of the lens affects the Depth of Field. The shorter the lens, the deeper the DoF
The amout of 'Depth of Field' you get is therefore determined by a product of..
1. Aperture
2. Distance from object.
3. Lens Length.
2. The amount of DoF is not necessarily equally proportioned to front and rear of the object.
On a shorter lens, you will have much more DoF 'behind' the point of focus, than in front (say 2/3 behind, 1/50 in front) where as on longer lenses this will change to 50/50 (on say a 400mm lens)
Alan.
1. Depth of field is also affected by a couple of other factors.
(i) The closer you are to an object, the narrower the depth of field gets.
(ii) The length of the lens affects the Depth of Field. The shorter the lens, the deeper the DoF
The amout of 'Depth of Field' you get is therefore determined by a product of..
1. Aperture
2. Distance from object.
3. Lens Length.
2. The amount of DoF is not necessarily equally proportioned to front and rear of the object.
On a shorter lens, you will have much more DoF 'behind' the point of focus, than in front (say 2/3 behind, 1/50 in front) where as on longer lenses this will change to 50/50 (on say a 400mm lens)
Alan.
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Kit 1 Canon 5D Mk11 EF 85mm F1.2 L EF 17-40 F4 L EF 100-400 F4.5-F5.6 L EF 50mm F1.8 Sigma F2.8 28-70mm |
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