Problem with depth of field

[beantowner2]

I have a Canon PowerShot G12 and haven’t been able to vary the depth of field in my photos.  When I set it to aperture priority with a low f stop, the depth of field looks the same as if I use a high f stop.  It also looks the same as if I shoot the picture on Auto.  What’s wrong?

[Waddizzle]

Most likely distances between camera, subject, and background.

http://www.dofmaster.com/doftable.html

To use this table effectively, look up your camera model in the drop down list.  It's way down the list with other compact cameras.

[jrhoffman75]

If you are shooting at the wide angle rangle of the camera the depth of field will be very great even with a wide open aperture.

[diverhank]

To maximize the depth of field:

1. set largest aperture (lowest Av value)

2. Put your object farther away from the background

3. Move your camera as close to subject as possible

4. Zoom in as much as possible (if your lens is a zoom lens). The higher the Focal Length, the more depth of field you'll get.

For wide angle focal length, depth of field is deep and you might not be able to blur the background enough.

[ScottyP]

Also, the smaller sensors of the Powershots naturally give more DOF than a larger sensor.   You may need to use most if not all the 4 strategies listed above at the same time to get the shallow DOF look you want. 

[jrhoffman75]

Hi diverhank. I think you have some errors.

Minimize DOF, not maximize. 

Higher the focal length less DOF. 

[diverhank]

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@jrhoffman75 wrote:

Hi diverhank. I think you have some errors.

Minimize DOF, not maximize. 

Higher the focal length less DOF. 

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Thanks. I meant minimize. Dof.

[beantowner2]

For the photos I'm doing, I usually don't have any control over how close I am to the subject.  What size sensor do I need in order to get reasonable control over dof - preferably equivalent to what I got with my old Olympus film camera?

[jrhoffman75]

Assuming your Olympus film was 35mm, a full frame DSLR or MILC would be equivalent. Crop sensor DSLR or MILC would also work.

[Waddizzle]

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@beantowner2 wrote:

For the photos I'm doing, I usually don't have any control over how close I am to the subject.  What size sensor do I need in order to get reasonable control over dof - preferably equivalent to what I got with my old Olympus film camera?

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Without knowing specific distances or focal lengths, there is no way to give you a specific answer. 

If you have not taken a look at the link that I posted above, I strongly encourage you to do so.  You will be able to compare apparent DoF between different cameras, distances, and focal lengths with just a few clicks.  While film cameras are not listed in the database, select any full frame camera body, and it should give you equivalent results.