Depth of field, how to improve?

Question

I've got a Canon Powershot A570 IS

I've tried various apertures on the low end (larger opening) but I can't get the "blurred" effect in the background to improve the depth of field. Are there other settings that could come into play to improve this?

Not sure if this link will work, but using this "eHow" guide as a reference my best depth of field pictures are are below the quality shown in "step 1":

http://www.ehow.com/how_2112025_cameras-aperture-change-depth-field.html

Focal length...increased or decreased to see the effect?

Answer 1

They forgot to mention that focal length does play an integral part in achieving the blurred effect that you speak of. If you are using a wide angle lens, say anything around 28mm and below, you are going to find it impossible to get this effect unless you are really close the the object you are photographing. I suggest you use the largest focal length your camera offers in addition to the largest aperture. For example if your camera lens has a maximum focal length of 150mm, then use that with the biggest aperture you have, say F2.8. If this doesn't work so well then try getting as close as possible to your subject as well.
another thing they forgot is this thing called the scheimpflug principle for all those who have a lensbaby or a viewcamera. Tilting the lens forward will actually help to increase your depth of field, whereas tilting it upward will help to achieve selective focus.

Answer 2

Two things work in concert to control the depth of field; f-stop and lens focal length. There is a third consideration - focus point. See ** for explanation.

Holding the f-stop constant, the depth-of-field decreases as the lens focal length increases, and increases as the lens focal length decreases. That is, a wide angle lens will have a deeper depth-of-field than a tele lens if both are set at the same f-stop. This holds true regardless of the focus point. **

Holding lens focal length constant, the depth-of-field decreases as f-stop decreases (the hole is getting bigger), and increases as the f-stop increases (the hole is getting smaller). This holds true regardless of the focus point. **

** Holding both f-stop and focal length constant, the closer the focus point is to the camera, the shallower the depth-of-field. Similarly the further the focus point is from the camera, the deeper the depth-of-field.

This is why everything in a pic from a pinhole camera appears to be in focus. High f-stop (tiny, tiny opening), short lens length (no lens) and focus point nearing infinity.

Answer 3

The link you provided uses a Nikon D50 camera. The sensor in the D50 is nearly twenty times bigger than the one in your A570-IS. SO...

It's going to be darn hard to "de-focus" too much using a digital camera while keeping the main subject in sharp focus. The smaller the sensor, the greater depth of field you will have. Generally speaking, the smaller the camera, the smaller the sensor. Your A570-IS has the smallest commonly available sensor. Most of the pictures you take with a digital camera are quite sharp from near to far distances and there is a reason for that which I will explain.

While we speak in terms of the 35 mm equivalency of digital lenses, don't forget that the digital sensors are usually smaller than a full-format 35 mm frame. Most of the more popular point and shoot cameras - including yours - have the smaller sensors. It's only about 5 mm wide and 4 mm high. The 3X lens required to cover that angle of view is an ACTUAL 6-17 mm zoom lens. At these focal lengths, the background is going to almost always be in pretty sharp focus.

In other words, if you WANT to defocus the background, you are going to have to work pretty hard at it. You would have to zoom to the longer end of the lens and set the aperture open as wide as it will go, if your camera even allows you to control the aperture, and get pretty close to your main subject while having the background a fair distance away.

Put your subjects quite a distance in front of any background that will be visible in your photo. You could use a garden of flowers and stand your subjects 20 yards or so in front of them. Try the portrait mode to shift things towards a larger aperture, zoom the lens out all the way, and move YOURSELF backwards or forwards in order to frame the picture as you would like it. In summary, you want to use a longer telephoto length, position yourself as close as you can to the main subject to compose properly, and place the main subject as far from the background that you wish to have out of focus as you possibly can.

The bigger the sensor, the easier it will be to achieve pleasing bokeh. This means moving to a dSLR, which all have sensors about 20 times bigger than the typical P&S digicam. If you want to really go for brokeh (very bad pun intended), you can get a Canon 5D and you will get exactly the same effect you are accustomed to in a 35 mm camera, since the sensor is the same size as 35 mm film.

Here is an example with a point and shoot camera, although it does have the larger sensor (1/1.8") that makes it easier to blur the background. Even though this is macro mode and f/2.8, where the background should blur the most, it's not terribly blurry because it's relatively close to the subject.

http://www.flickr.com/photos/samfeinstein/872732755/

Here is an example with a point and shoot camera, so it CAN be done. The background is much farther away, though, and this is the larger sensor size.

http://www.flickr.com/photos/samfeinstein/843563558/

Compare that to this image, though, which has a similar subject-to-background distance. The SLR has the obvious advantage.

http://www.flickr.com/photos/samfeinstein/408446616/

Wikipedia does pretty well on the subject of depth of field. See: http://en.wikipedia.org/wiki/Depth_of_field

See also: http://www.photo.net/learn/optics/dofdigital/

See also: http://www.flickr.com/groups/dof/

Answer 4

With that set-up there is in elementary terms the aperture to administration intensity of field and, as others have reported, at close focussed distances, DoF is minimum. in case you will make a habit of photograph'ing surfaces which at the instant are not parallel to the sensor/action picture very % up then you definitely might desire to evaluate a technical digicam the place the plane of concentration may be sloped in terms of the sensor/action picture plane. this would not truthfully improve DoF inspite of the undeniable fact that it does enable you to place it the place you go with it to be

Answer 5

Visit expoimaging.com and check out their ExpoAperture2. It is a DOF "calculator" that tells you DOF at different focal lengths and f-stops. You can read a review of it at shutterbug.com - just type expoaperture2 in the Search box.

Answer 6

Get a DSLR camera if you want this effect. It's too hard with a point and shoot camera.


Try photoshop and use the blur tool on your background.

Answer 7

Large aperture (small F stop)
Move closer to subject and zoom out

Answer 8

explanding on Mr Wallaces answer:

the wider the lens you use the harder it will be, the longer the lens the easier it will be. so use the widest apeture and the biggest zoom you can, have the person close to the camera and the background far away

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