How many of us are able to calculate the exact Depth of Field for all of our lenses at the various apertures and hyperfocal distances when there is no depth of field scale on the lens to use (as is the case now with most new lenses), or even if there is a scale if you are using an older lens?
We know, or should know, that the smaller the aperture and the further we are from our point of focus, the greater is the depth of field. As we get closer to our subject the depth of field becomes more critical. This can be a major factor in macro photography, where you need very small apertures to get the most depth of field. With this, lighting usually becomes another problem.
Using a 50 mm Macro lens set to take 1:1, that is life size on the film plane, and an aperture of f32, then your depth of field can be as small as 3 mm. In portrait photography a focal length lens of between 100 - 150 mm is considered best for natural looking portraits. The depth of field available at say, 3 metres at f11 with a 150 mm lens, is 160 mm using these tables.
The amount of depth of field available becomes difficult to calculate if we are using a zoom lens or a digital camera where depth of field scales are not shown.
This website may help: http://www.dofmaster.com/dofjs.html
The list of cameras available is in alphabetical order and the tables for any and all cameras are available using the drop down list, as is the distances in either feet and inches or in metres.
On this web site there is an interactive depth of field calculator where you are able to find out the depth of field available for all lenses of all focal lengths, including digital camera lenses at any chosen aperture. If you are handy there are also instructions on how to make a depth of field calculator which, if made small enough, will fit on a lens cap.
This is an interesting site and well worth a visit.
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