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Old Jul 21, 2004, 7:18 AM   #1
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while using non-diital SLR when i want to get dof all i need to know is the distance of the object (detail that is given by the lens) and then calculate the dof i want by choosing the right aperture that will give the dof and then adjusting the shutter that fits the aperture. i never calculated focal length or used data sheets do get the effect i need. but, couple of days ago i had a chance to play abit with my friend's S7000, and found out that in order to get dof i need to zoom so that the focal length be higher. besides the fact that zooming made the whole scene i wanted not to fit to the image, i couldn't get the effect as i wished.

does the dof is only zoom dependant? changing the aperture made a minor change if any at all...

is there a way in digital cams to see how far is your object?

are the rules of SLR's dont effect digital cams?

what is your way to calculate dof?
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Old Jul 21, 2004, 1:39 PM   #2
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Danny, Depth of Field is based on Aperture, Focus Distance, and Actual (not 35mm Equivalent) Focal Length.

Because the sensors in consumer Digital Cameras are very tiny, compared to 35mm film, the image circles can be smaller, too. This allows manufacturers to use amuch shorter length lens, for the same equivalent focal length in a 35mm camera.

As a result, you have MUCH greater Depth of Field, at any given 35mm equivalent focal length, for the same subject distance and aperture.

Even though the 35mm Equivalent Focal Length is 35-210mm, the actual focal length of the lens on the Fuji S7000 is only 7.8-46.8mm.

Load this Depth of Field Calculator and selecta camera model. Then, plug in the actual focal length of a lens, along with aperture and focus distance to calculate the Depth of Field


Experiment with this Calculator, and you'll get a better idea how these parameters (Aperture, Subject Distance and Focal Length), impact the amount of a photo that is in focus with a small sensor camera like the S7000.

The same rules apply. The larger the aperture (smaller F/Stop numbers), and the closer you are to your subject (focus distance), and the more zoom you use (actual focal length), the shallower your Depth of Field.

The difference is that you're using a much shorter focal length lens with a consumer digital camera. So, many users find it difficult to make subjects stand out from backgrounds, by using larger apertures to decrease Depth of Field.

Of course, many consumers consider this a plus, since more of the image will be sharp, compared to using a 35mm camera at the same equivalent focal lengths.

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