Focussing subject while blurring the background

By focal length, do you mean using the zoom?
My camera has 10x optical zoom, so I should use it and at the same time use a wider aperture like 4.0+ & get close to subject to get the desired effect called bokeh?

First, good luck on those exams. I remember those days. Better you than me. :lol:

Don't exceed your camera's optical zoom capabilities. Most P & S cameras also have "digital zoom" which kicks in after you've exhausted the optical zoom. This really affects the quality of the picture.
 
Play with your camera. Get up-close-and-personal with your subject. You want your subject to be close and your background to be far away. My example below was taken with a Canon PowerShot G9. I wasn't trying for the depth of field effect, but I got it. I couldn't get very close to the flower so I had to zoom. My G9 was working in Programmed automatic mode. Aperture was automatically chosen at f4.8. The grass in the background was relatively far away.

 
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I am just getting into photography, but have had similar challenges. So, take this advice with the fact that I don't know what I am talking about :)

I started with a Canon G9 and while it will blur the background, I had to be:
- zoomed way in
- very close to the subject
- large aperture (small f number)
While the G9 can provide large apertures, it seemed that the depth of field it produced was proportional to the distance from the lens to the subject.

It was extremely hard to blur the background on people shots and get much of them in the picture. As I have a new baby on the way, I just decided to upgrade to a D40, which seems more than willing to blur the background pretty easily. I think sensor size does play an important roll.
 
I am just getting into photography, but have had similar challenges. So, take this advice with the fact that I don't know what I am talking about :)

I started with a Canon G9 and while it will blur the background, I had to be:
- zoomed way in
- very close to the subject
- large aperture (small f number)
While the G9 can provide large apertures, it seemed that the depth of field it produced was proportional to the distance from the lens to the subject.

It was extremely hard to blur the background on people shots and get much of them in the picture. As I have a new baby on the way, I just decided to upgrade to a D40, which seems more than willing to blur the background pretty easily. I think sensor size does play an important roll.

Same with any camera

Use long foca length, be close to subject, use large aperture.

The problem with compacts is (as you have noted) the size of the sensor. That affects the available dof greatly. sensors = large dof
 
I am back. Sorry for the delay, as I have been facing severe net crisis.
Well, I tried as per your instructions & here are the results.

my.php




The above image was shot under the following settings,

ISO : 200
WB : Sunny
Exposure Time : 1/100 of a second
F Number : 8.0

What do you think? Can I get more blur for the background? Image is shot using a Canon SX 100 IS.



Also have a look at this image,



Shot with the same settings except the F Number was 2.8
What is this effect known as?
 
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What do you think? Can I get more blur for the background? Image is shot using a Canon SX 100 IS.
Yes, you can get more blur if you zoom the lens out more and get the camera as close to the subject as possible and open up the aperture to f/2.8.
Shot with the same settings except the F Number was 2.8
What is this effect known as?
The camera didn't focus on the phone, it focused on the scene behind it. Can you manually select a focus point with that camera?
 
Yes, you can get more blur if you zoom the lens out more and get the camera as close to the subject as possible and open up the aperture to f/2.8.The camera didn't focus on the phone, it focused on the scene behind it. Can you manually select a focus point with that camera?


I am confused. To blur the background should one increase the F Number or Decrease ?

And yes I can set the focus manually. I need to check with the camera.
There is something known as Evaluative, Centered Weighted Average & Spot. Are these related with the focus?
 
I am confused. To blur the background should one increase the F Number or Decrease ?
You need to use a lower f/stop number (lower f/stop = bigger aperture opening...higher f/stop = smaller aperture opening).
There is something known as Evaluative, Centered Weighted Average & Spot. Are these related with the focus?
No, those are for exposure metering.
 
I own a Canon SX 100 IS.
Any idea how to set focus manually on it? It isn't a DSLR but still a prosumer camera so I guess it does has the options to set focus manually. Will check this out.

So I need to click an object with as much zoom as possible and using a low F Number i.e. wider/larger aperture?Right?
 
Again I went as per the manuals & this time I am highly impressed with the results I got.




Settings:

WB : Sunny
F Number : 3.5
ISO : 400
Exposure Time : 1/1600 of a second

But why is that when I zoom in the F number change from 2.8 to 3.5? At no zoom, it's 2.8 but it shoots up when I increase the optical zoom.
 
Here is another one I shot today,



Settings:

ISO : 400
White Balance : Sunny
F Number : 4.3
Exposure Time : 1/1600 of a second


Please comment. :)
 
The most important aspect is actually NOT aperture.

I disagree, if you change the aperture you don't change what the sensor sees, if you change the focal length, you change what the lens sees... You get a completely different picture, rather than just selective blur, which is what you get by widening the aperture.
 

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