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Old Apr 21, 2003, 5:08 PM   #1
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Default depth of focus help needed

I give up. Maybe you can help. I have a Nikon 5000 digital and can't get it to take a picture of a flower with the background blurred.

Can't it do that? Seems like I've done it before, buy maybe that was with another camera. I tried Manual mode and selected every combo of apeture and speed available. The background is always in focus as well as the close subject.

I tried it with macro selected and not selected.

What gives?
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Old Apr 21, 2003, 5:18 PM   #2
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This a common problem with most consumer digicam, if the macro mode does work (get as close as you can with the aperture wide open) then:

The easiest way is to go in Photoshop, duplicate the layer, apply Gaussian blur (you can also change opacity), and then use the eraser tool to remove the blur from the flower!
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Old Apr 21, 2003, 8:03 PM   #3
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It's called "depth of field" and a lot of digicams have very large depths of field. That's frustrating for the portrait photographers who want a blurry background. Several tricks:

1. Get as close to the subject as you can and have the background as far away as possible.

2. Use the widest possible aperture.

3. Use the longest focal length available.

4. Use an add-on teleconverter.

5. Use an add-on close-up or macro lens.

6. If your camera has manual focus, start with the camera focussed in front of the subject and adjust it until the subject just barely comes into focus. If you're careful, you can do this and leave the background out of focus.
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Old Apr 24, 2003, 1:16 PM   #4
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Play with this site (depth of field simulator):
http://www.photonhead.com/exposure/simcam.htm

Examples:
http://www.photocourse.com/03/03-03.htm
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Old Apr 24, 2003, 11:31 PM   #5
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Default Re: depth of focus help needed

Quote:
Originally Posted by blacksmith1
I give up. Maybe you can help. I have a Nikon 5000 digital and can't get it to take a picture of a flower with the background blurred.

Can't it do that? Seems like I've done it before, buy maybe that was with another camera. I tried Manual mode and selected every combo of apeture and speed available. The background is always in focus as well as the close subject.

I tried it with macro selected and not selected.
First, what you asked should be "depth of field" (DOF) rather than "depth of focus" because the latter means a different thing.

Second, since the image sensor of a non-full-frame digital camera is considerably smaller than that of a 35mm film care, the depth of field (i.e., the area in which subjects appear to be sharp) is considerably larger than that of a film camera. This means at the same aperture and the same view angle, the DOF of a consumer digital camera covers an area. A direct consequence is that one can hardly blur the background. This is an inherent advantage or disadvantage of consumer level digital cameras. Whether it is an advantage is in the eyes of the beholder.

However, we can partially overcome this problem by using a larger aperture, a longer focal length, a teleconverter, and/or a close-up lens as mentioned in other posts above. While in doing so the background ma be blurred somewhat, the DOF is also reduced, usually significantly. This means you may not get the depth of your main subject within the DOF.

There is a commonly used trick: isolating the background. Try to shoot from a different angle so that the background is as simple as possible. If it is necessary, you may use a single color cloth to cover the background (to make it simple).

Another thing I'd like to point out is that many DOF calculators simply use textbook formulae. This may work to some degree because we really don't know the key factor "radius of circle of confusion" and everyone guesses, :-) Unfortunately, when a lens is in macro mode, those formulae usually yield a too-large DOF.

The "Depth of Field" page in my Coolpix 4500 user guide provides a general overview and a theoretical way of computing DOF. Hope this will provide some help.

CK
http://www.cs.mtu.edu/~shene/DigiCam
Nikon Coolpix 950/990/995/2500/4500 user guide
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