subject clear with background blurred

I need help, i'm really a newbie in photography, like the point and shoot guy

only, i'm trying out this feature that's where my subject is sharp or clear

while the background is blurred. I'm using a Sony Cyber shot DSC-V3 7.2 mega

pixel camera. Please help....

 

I've already read the instruction manual and tried ajdjusting the aperture

boith high and low, and i'm only getting a blurred photo

 

thanks

To get a sharp picture you have to focus the camera, either using auto focus or setting the correct one of the 13 settings the camera manual focus system permits. It is unlikely that you will get very soft backgrounds with the subject sharp with your camera unless you are close to the subject and the background is a good way behind, and you use the narrow telephoto end of the zoom.

 

It sounds as if you have choosen manual focus but have omitted to focus the camera .. read that section of the manual.

Your camera uses a small sensor which results in its tendency to have a deep depth of field (ie: a wide distance over which items will be in focus). To create a photograph where the subject is in focus and the background is not, you can't just rely on a wide aperture (by that, I mean using a numerically small aperture like 2.8 or whatever the smallest number f-stop your camera supports at the focal length you're using).

 

You should also use a telephoto focal length and move close to your subject. The combination of tele, close focus, and numerically small aperture value will result in the subject being in focus (assuming you're focusing on your subject) and the background being out of focus.

 

If you're getting blur, it's possible your shutter speed is too slow.

 

larsbc

Alvin,

 

What you're asking for is the ability to use a concept called 'selective focus'. That is where the subject you choose is in sharp focus and the background is pleasantly blurred out.

 

This effect is controlled by two mechanical aspects, neither of which yoru camera has much control over with regard to what you want - but you might be able to get something like what you want. More on that later. There is a third aspect as well, and we'll put that near the end.

 

The FIRST aspect is aperture. That's the device inside the lens that opens and closes to let in more or less light depending on the circumstances the camera sees. Not the shutter - that turns the light on and off to record the photo. Imagine forming a circle by curling your thumb and forefingers into a tunnel shape and looking through it. If the circle is large, that's a large aperture. If the circle is small, that's a small aperture. Large apertures let in more light, small apertures let in less light. With me so far?

 

Now, aperture is designed to let in more or less light, as I said. But it has another aspect - smaller apertures make things tend to be more in focus than larger apertures for a longer distance into the photograph. What I mean by that - an itty bitty hole makes almost all your photograph in focus (that's how pin-hole cameras work without a lens at all). A really large hole means that only the part of the photo you focused on is really in focus.

 

The shutter speed (the lens opening and closing) and the aperture work together to make the right amount of light hit the film (or camera sensor, for a digital camera). You can change the aperture or the shutter speed, but the total amount of light entering the camera should remain the same for any given photo. So, if the camera was planning to keep the shutter open for 1/125 of a second at an aperture of f/16, you could manipulate your camera such that the aperture is wider (smaller aperture number is larger hole, sorry) and the shutter is faster and everything would be OK. In this case, the aperture might be f/8 (twice as big a hole) and shutter speed of 1/500 of a second (twice as fast shutter speed). With the bigger aperture (smaller number, remember), the resulting photo should exhibit the qualities of having less of the background in focus (more on this later). In reality - one often has to select apertures of f/2.8 or even wider to really see the difference. Again, more on that later.

 

The SECOND aspect is what is called 'focal length'. That's your zoom. The more you 'zoom in' on a subject, the longer the focal length of your lens. When you zoom out, you're making the lens focal length shorter. With me so far? All things being equal, a longer focal length has less depth-of-focus (DOF) than a shorter focal length. In the 35mm film world, a 105mm lens is often considered a 'portrait' lens, while a 28mm lens is considered a 'wide-angle' lens. With the 28mm lens, it is hard to make the background go out of focus, even with a really wide aperture. With the 105mm lens, it is really easy to get the background to go out of focus, even if you don't select a wide aperture. There is some physics behind all of this, but if you just remember it, you don't have to go to higher mathematics to understand why.

 

OK, so now we have two things we can do to make backgrounds go out of focus. The first is to select a wider hole (smaller number) aperture. The second is to select a longer focal length (zoom in on your subject). With a 35mm film camera, that should do it. With a digicam, it does not, quite. Why? More on that...hang on...almost there...

 

There is yet another facet that can help. Aspect number THREE! Move in closer to your subject, even though you are zoomed in already. There is some more math behind this, but basically, getting closer to your subject changes the distance into the background that stays focused.

 

So three things now:

 

1) Open aperture.

2) Zoom in.

3) Get closer.

 

How close? Well, how close can you get and still not over-fill the frame with what you want to photograph? If you shoot macro - bugs and flowers and stuff, you'll quickly notice that the background is always blurred out. That's due to aspect number THREE!

 

Now, there is a drawback to shooting digicam instead of 35mm film when you want to make your background blurred out. That is due to the fact that the digital sensor is an itty bitty tiny thing, and a single frame of 35mm film is a hulking giant by comparison. Again, more math if you wanted to understand why, but consider this - your lens on youd digicam has a focal length range printed on it. Probably something like 7mm - 28mm or something like that. You may have read elsewhere that this is 'equivalent' to a 35mm - 210mm zoom on a 35mm film camera. And it is, in terms of how wide and how narrow the lens can be - called 'field of view'. But (again with the math, just trust me on this) a 7mm lens is always a 7mm lens for the purposes of determining DOF (depth of focus). Even though it has the same field of view as a 28mm lens in the 35mm film world, it still acts like a 7mm lens for the purpose of how deep the focus is. It is REALLY HARD to make a 7mm lens NOT be in sharp focus from front to back. Except - getting really close, like macro close - like aspect THREE (above).

 

If you really, really, want to have a blurred background - you can try all three aspects:

 

1) Wide aperture.

2) Zoom in.

3) Get close.

 

If that doesn't work for you, sadly, you need a bigger sensor, such as you would find in a digital SLR or a film camera. For what it is worth, a medium format film camera or large format film camera can produce LOADS of DOF effects with no effort at all - which leaves even the 35mm film camera in the dust. It's all about the size of the sensor, if you can't make the aperture hole any bigger or zoom in any more.

 

There are online calculators that can help you get an idea of how deep into the photo the sharp focus will be:

 

http://www.dofmaster.com/dofjs.html

 

It's free. You enter the things you do know, like sensor size (it will help you figure out your sensor size), lens focal length, how far away your subject is from you, and what aperture you want to use, and it will tell you:

 

The near limit of acceptable sharpness (how close the focus point is)

The far limit (how deep the focus goes into the background)

The total DOF.

 

There is more information, like hyperfocal distance, and so on, but you can ignore that for now.

 

Let's take an example:

 

I chose your camera (Sony DSC-V3) and fully zoomed in (34mm) and an aperture of f/2.8. I said that your subject was 10 feet away from you:

 

8.89 ft away from you is the closest 'in focus' distance.

11.4 ft away from you is the furthest 'in focus' distance.

2.54 ft is the total zone of sharpness.

 

Does that mean objects way, way, in the background of this photo will be way out of focus? Well, they will be out of focus, but how much out of focus you have to try and see. A little blurry or way blurry you'll get a feel for.

 

If I tried the same numbers above but for the lens set to 7mm (zoomed all the way out), the near focus distance would be 2.51 feet, and the farthest distance would be infinity - so just about everything would be in focus.

 

Play with this calculator - it's a good tool to previsualize how your photo will look.

 

Experiment with different things - try using your camera's menu to take more control over the exposure, get closer to your subject, zoom in.

 

Congratulations - you're advancing beyond the boundaries of 'happy snapping' and into the realm of the enthusiast. Take your time, ask questions, try things and pay attention to what happens. You'll get it.

 

Hope you find this helpful!

 

 

By the way, I just found an error in what I said earlier. I said "Depth of Focus" and what I meant was "Depth of Field". Both are abbreviated "DOF". However, if you read Depth of Field wherever I said Depth of Focus, the story is the same. Sorry for any confusion.

there is some imprecision in comparision of DOF for lenses 35mm and small digital sensor. DOF depends on probably size of prints and viewing distance so 7mm lens don't have the same DOF on sensor, as it would have on 35mm.

 

I don't have numbers - but we could agree on such a method - assume that film is used at same resolution as sensor (dimensions 4:3 or 2:3 we would ignore, lets measure it just in megapixels). Count size on equivalent pixel size on film and pixel size on sensor (maybe there should be some ajustments, but we will get Circle of Confusion (CoC)).

 

Only then we can theoretically compare DoF for lets say 28mm lense on 35mm film, and "35mm equivalent" of some digital camera.

 

Acctually how they count those "35mm equivalents" on 3:4 sensors?

Martin,

 

With the utmost respect, I left that mumbo-jumbo out. It's all true (circle of confusion, etc), but irrelevant to someone who just wants to learn how to make the subject sharp and the background blurred. We can count how many angels can dance on the head of a pin, but ultimately, so what? In our desire to be precise in our definitions, we've chased away the person who wishes to know how to do a thing, not why it is what it is.

 

Simply put - a 7mm lens on a digicam acts like a 28mm lens on a 35mm camera in terms of field of view (how 'wide' it is). But it still behaves like a ultra-wide 7mm lens in terms of the DOF it produces. That's dependable and can be used to roughly estimate what you're going to get when you take a photo - circles of confusion and what-not have little real-world application to a person who is a self-admitted point-n-shooter.

 

But I agree with you in the technical terms. It is a good thing to be precise in the long run.

I'm a newbie and I only own a P&S camera (Cannon Digital Ixus) which does not have settings for aperture and shutter speed. Does this mean I won't be able to achieve this result?

Jon,

 

It matters less that you don't have aperture control and matters more than you're using a digital point and shoot (per the discussion above). The smaller sensor plus the very wide angle lens required means throwing the background out of focus is much more difficult. If your subjects are people, one way to achieve a semi-out-of-focus background is to 1) have your background very far away 2) frame your subject using the full zoom of your camera (which means you'll need to step backwards).