Re: Help for a Newbie?
Wild guess here ... I'll bet your son's name is Tobey? 
I can't help with the specifics of your camera, but in general it works like this ...
The sensor in your camera needs a certain amount of light to take a good shot - and that amount is always pretty much the same. To get the right amount we only have a couple of controls to play with (ignoring ISO for now) - The shutter speed, and aperture (or "size of the hole that the light enters through").
Shutter speed and aperture are linked ... the bigger the aperture (lower F-Stop number) the more light that gets let in - and so the faster the shutter has to open and close to get the right amount of light. If you use a small aperture (big F-Stop number) then the shutter must stay open longer to let more light in. (a bit like the time it takes to fill a bath - the more you open the tap (aperture) the less time you need to keep the water running (shutter speed) to fill the bath.
So a good exposure is always a case of getting the right combination of aperture and shutter speed. Most cameras allow you to pick one - and the camera will choose the other to ensure things are nicely balanced (although you may be able to override the camera and choose both).
Although - in terms of exposure - a fast shutter speed / wide aperture or a slow shutter speed / narrow aperture may give you the same exposure, varying the aperture also affects what's called the "Depth of Field" (DoF) or "how much background is in focus as well as the primary thing your photographing", In your case you're wanting feet in focus, but a blurry background - so you want a narrow depth of field, and a (comparitively) high shutter speed. (I say comparitively high because the actual shutter speed may still be quite low if you're shooting in a place that's not very brightly lit, but it'll still be a higher shutter speed than it would have been had you have taken the shot in the same light with a narrower aperture).
ISO is a way to get higher shutter speeds for a given aperture, or in turn a narrower aperture for a given shutter speed (ie still get a good shot in poor light - it helps alleviate camera shake from too low a shutter speed) - but with there being no such thing as a free lunch, the trade-off in using a high ISO setting is that you'll start to see a lot of digital noise in your shots.
So - putting it all together, you'll get the best background blur if ...
- you use the narrowest aperture (lowest F-Stop number),
- get the subject as far away from the background as possible (ie feet dangling in the air with a wall several feet behind (no pun intended!) will have more background blur (called "bokah") than one where the feet are only a few inches above a carpet.
- Zooming in helps (it increases the focal length of the lens) - but only to the point where you don't start backing up to get the same field of view (because camera to subject distance decreases background blur with an increase in distance) (or conversly, the closer you can get the camera to your subject, the more blurrier the background will be) (although there will be a minimum distance that the camera will focus to - although Macro mode may allow you to focus a bit closer to the feet).
So - those are the basics - wether or not you can get sufficient blur with your camera I have no idea - it's the kind of teritory that SLR cameras and fast lenses (apertures of 2.8 or wider) excel at.
Hope this helps,
Cheers,
Colin - pbase.com/cjsouthern
Last edited by Colin Southern; 12th January 2009 at 05:49 AM.
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