Looking hard at the Canon Powershot S1 IS. My wife wants one that can have the subject in focus and blur the background. http://consumer.usa.canon.com/app/pd...a/s1is_bro.pdf says the camera has something called. "selectable focusing point."
Is that what that means or is that something else?
Not sure if that's what it does or not but in photography, that effect is a result of the aperature setting. The bigger the lens aperature (smaller value) the shallower the depth of field or focus is. By using a small aperature value (large opening) you will get subjects in focus with backgrounds blurred. Any camera that allows manual aperature, f-stop settings can do this.
The distance of focal length (zoom), distance from camera to subject, and distance from subject to background affects this too but the cause is the aperature value.
No, that has nothing to do with having a shallow depth of field.
Selectable focusing point means you can tell the camera where in the frame you wish to focus. Generally cameras focus at the centre of the frame; with selectable focusing point you can select other areas. Where you can select depends on the camera itself. EOS 1 and 3 series have 45 points!
I'd like to add to backpackerx's comments that there's an additional factor, and that's how much you want to enlarge the photo by.
If your wife needs a fairly shallow depth of field, I'm afriad most of these cameras can't do it, due to the smaller sensors leading to very short focal lengths. Your options are then to get a DSLR, or to use Photoshop to do the blurring instead.
Perhaps you can give us an example of how shallow the depth of field, and the amount of background blur that is needed?
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Baka. Soku. Zan. - The justice behind the dysORDer.
http://consumer.usa.canon.com/ir/con...4&modelid=9824 at the very bottom. The boy/girl hugging each other with the trees in the background blured. I know that is on the Canon page, but that doesn't mean that camera did that.
Yea, it's not impossible.. but you'll probably need to use the maximum 10x zoom and stand at the appropriate distance to the subject to get that. It'll also depend on the distance of the background to the subject.
If you absolutely need to get that kind of blur consistently, then you'll probably need to follow one of the two points I made above, that is, get a DSLR, or use Photoshop (or similar software).
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Baka. Soku. Zan. - The justice behind the dysORDer.
The separation of subject/background by blurring the latter is also affected by the distance between the main subject and the background.....and even by the distance between the photographer and the main subject. In the pic you cited at the Canon site, the background is clearly quite some distance behind the boy & girl. Hence, with a large aperture opening, the blurry background. Had they been standing right at the edge of the wood line, the blur effect would have been far less pronounced....even with a large aperture set on the camera. Chances are, the background would still have been somewhat blurred, just not as demonstrably as in this pic.
'Back in the day'......lens makers used to put Depth of Field markers on the lens barrel. So, if one's subject/focal point was at 8ft from the camera and the aperture was set at say, f16, it was easy to glance at the lens barrel and tell that everything between 5 ft and 25 ft (or whatever) would be 'in focus'. These DOF markets are FAR less common these days, and I think it's a pity. It was a handy little tool.
Well, sinze everyone wants zoom lenses nowadays, DOF markers aren't practical, unless some LCD panel is installed to provide an on-the-fly calculation of DOF.
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Baka. Soku. Zan. - The justice behind the dysORDer.
Well, sinze everyone wants zoom lenses nowadays, DOF markers aren't practical, unless some LCD panel is installed to provide an on-the-fly calculation of DOF.
Zoome lenses don't matter. Lens focal length has nothing to do with DOF.
Heh, knew someone would post that up sooner or later.
If you look at the mathematical equations for DOF calculations, you'll see the variables include:
1. Focal length
2. Distance to subject
3. Circle of confusion (related to the enlargement factor I was talking about)
4. Aperture size.
What that article demonstrates (and states at the beginning) is that when magnification remains the same, the DOF remains the same too. However what it neglects to mention is that magnification is dependent on focal length and distance to subject; double one and you'll have to double the other to keep magnification constant, and thus the experiement is flawed as it is changing TWO variables at the same time. I'm not going to torture everyone (including myself) by doing the derivation for the DOF equations, but you can try plugging in the numbers into a DOF calculator and you'll find that is indeed the case.
edit: ack, brain freeze, edited the bit on keeping magnification constant.
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Baka. Soku. Zan. - The justice behind the dysORDer.
I just remembered, there is a camera that'll show you what your DOF is even with a zoom lens, and that is the extremely gadgety Minolta Dynax/Maxxum 7 SLR. I assume the digital version has the same feature. With a D lens, pressing the DOF preview button on the camera will show you the DOF (with a diagram even) right on the rear LCD!
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Baka. Soku. Zan. - The justice behind the dysORDer.
Question on digital cameras
Linear Mode
