changing depth of field?

[totono]

Does anyone know how exactly to change the depth of field in the S230 and also how tu use the focus lock?
Thanks!

[JohnMN]

The way you influence the depth of field is with the zoom settings, the aperture size, shutter speed and the amount of available light to you when you take a picture. On the Canon A40 when it is set to wide angle (no zooming) you will get an aperture of F2.8, this is the widest opening on this camera and lets in the most light. As you start to zoom in the aperture starts to close and so less light gets in. This affects the depth of field, with the aperture at its widest you will get a shallow depth of field and at its narrowest you will get a very big depth of field. Usually from in front of the lens to infinity (I think I've got that the correct way around - other contributors please change this if I have it wrong). As for the focus lock check the instruction manual.

JohnMN

[Tom W]

JohnNM is right - the larger aperture will give you a more shallow depth-of-field. On the other hand, a lens with a shorter focal length (wide-angle) will tend to give greater depth-of-field than that of longer (telephoto) length. What this means with the S-230 is that at at the wide-angle end of the lens, you can have an open aperture (f-2.8 ) which will tend to shorten the depth while you are operating at a shorter focal length which tends to lengthen the depth of field. At the telephoto end of travel, the aperture is closed down a bit (f-4.0 ) while the focal length is longer. They are opposing tendencies and I don't know which trend is stronger.

What I suspect you want is to control aperture and thus depth-of-field. This isn't directly adjustable on the S-230, though you sometimes can get the Camera to close down to a smaller aperture by increasing the ISO setting. I've been able to get a smaller aperture, up to f-9.0 on a bright sunny day by raising the ISO setting. I haven't discovered a pattern as to how the camera decides to close down the aperture, but I will continue experimenting to see if I can tell what the camera is "thinking".

As for focus lock, I agree with John - that's covered in the manual.

[paul c]

yeah , john & tom gave you really great answers to your question. about the focus lock on the S230/V3,you have to leave the LCD on,and place your subject in the center of the frame,press halfway and hold the shutter,till it beeps twice,then press the macro/infinity button,(w/o letting go of the shutter), AFL will be displayed on the left hand side of the LCD.,you can then let go of the shutter , recompose and shoot.. hope this helps ,,pc