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?

[smack53]

I have the PowerShot G12 camera and I use the 1.4x teleconverter on the barrel adpater to increase the focal length to 196mm (equivelent), and keep the subject as far from the background as possible. I shoot in manual mode with a wide open aperture, but since the sensor is small, the bokeh (blurred background) does not get as creamy smooth as with a larger sensor camera. Attached is a sample of one of the G12 shots I've taken:

Steve M.

[beantowner2]

I did check the link you posted.  Thanks for that information. (Sorry to take so long replying.)  I didn't know where to start looking in the data to find what I wanted, so was hoping for a seat-of-the-pants answer.

[beantowner2]

As far as a teleconverter goes, I am trying to figure out whether this camera is going to work for me before I put any more money into it.  But I have decided to set the mode to Manual and leave it there until I figure out how to use it.  Part of that will be getting used to operating the controls I want to operate without - at the same time - operating several that I don't.  I have trouble with that even with my tiny fingers.

[jrhoffman75]

You will get the shallowest DOF your camera can provide  by setting the aperture as wide as possible, the zoom setting as long as possible, and using the closest focus for your lens.

"As a practical matter, these are the the things that affect depth of field:

the f/stop
The smaller the f/stop (the larger the number, the smaller the diameter of the aperture), the more depth of field there is. At f/2 (small number, big aperture), you will have comparatively narrow depth of field, with little in focus on either side of your focus point; at f/16 (big number, small aperture), you will have comparatively more depth of field, with more subject matter in focus on either side of your focus point. I say "comparatively" for a reason. If you've read my f/stop page, you know that from a brightness point of view, measuring the amount of light hitting the film or sensor, f/2 is f/2 regardless of the lens. This isn't the case with depth of field. The amount of depth of field at f/2 will also depend on...

...the focal length of the lens
The shorter your focal length, the more depth of field you will have. A 20mm lens will have more depth of field than a 50mm will have more than a 100mm. With really short lenses, like 4 mm, you will have immense depth of field. With long lenses, like 400mm, you will have miniscule depth of field.

the distance to the subject
The closer you are to your subject, the less depth of field there will be. The further away you are, the more depth of field you will have."   From - "http://www.uscoles.com/depthoffield.html"

Whether or not that is an acceptable DOF for your purposes only you can decide.

[beantowner2]

P.S.  Thanks for posting the flower picture.  I see what you mean about the background, but I'll be happy if I can achieve that level of blurryness.

[beantowner2]

Thanks to everyone who replied.  All of your posts were helpful.  I am trying to figure out whether I can tag them all as the solution.