Blurred background depends on the focal length, the aperture, the distance between the camera and the focused object, the distance between the focused object and the background..

The most important viariables are the focal length and the two aforementioned distances. If the distance lens-subject is greater than the hyperfocal distance you'll never get a blurred background. If the focal length is short then the DOF will be deeper..

To get a blurred background use the longest focal length of your lens (85 mm if I'm not wrong) and use the maximum aperture at that focal length (f/5.6). The subject should be closer than the hyperfocal plane..

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72 mm, f/4, distance to the subject is about 15 m (a small sensor though 1/2.5").VictorBucuresti, Romaniahttp://s106.photobucket.com/albums/m268/victor_petcu/..

Have a look at this useful depth-of-field calculator:.

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

If you play with it you will see how important the distance to the subject is..

Suppose you have the lens set at 55mm and f/5.6 and the subject is 20 feet away; the total depth of field is 9 feet, from about 3.5 feet in front to 5.5 feet behind. It is unlikely that the background would be completely blurred. In contrast if the subject is 10 feet away the depth of field is now only about two feet, one foot in front and one foot behind the subject. In this case the background should be thoroughly out of focus..

Check it out before you spend lots of money on an expensive new lens .

Best wishesMike..

Thanks.

I have been trying to read about this and still confused on the hyperfocal distance..

Based on your example using the 10ft scenario, I see that the background distance is reduced, and the hyperfocal distance is 92ft..

When I change the f-stop to f2.8, it changes the hyperfocal distance to 185ft! This is what I dont get. What does this distance represent and is this a good thing or bad thing if I am wanting a blurred background?.

Thanks for your help..

The 50mm 1.8 is a good choice. I think that might be a good place to start. It's cheap..

For hyperfocal distance:http://www.dofmaster.com/hyperfocal.html..

I have that one thanks, and I agree, it is great, and I can get the blurred background in most situations where I am trying for it. I put that down to the f1.8..

But I am trying to get similar type photos (I know the prime lenses are better) with my zoom lens, but just cant achieve it at all. Hence why I was thinking I must change lenses to the 17-55 f2.8 to get the blurred results as I just dont seem to get them when using the 17-85 f4-5.6..

Ie the apature plays a big part to achieve this??..

Bengrow wrote:.

Ie the apature plays a big part to achieve this??.

Pretty big..

Other than lowering the f/stop to get more background blur, the next thing to do is zoom in to the telephoto side of the lens, and get as close to the subject as possible. You may find it isn't really possible to frame your subject and get background blur though..

You can get nice background blur with telephoto lenses too...

I have been trying to read about this and still confused on thehyperfocal distance..

Based on your example using the 10ft scenario, I see that thebackground distance is reduced, and the hyperfocal distance is 92ft..

When I change the f-stop to f2.8, it changes the hyperfocal distanceto 185ft! This is what I dont get. What does this distancerepresent and is this a good thing or bad thing if I am wanting ablurred background?.

Thanks for your help.

The hyperfocal distance is the distance you need to focus at to ensure that the depth of field extends back to infinity. (Obviously it will extend forwards some way from the hyperfocal distance as well). So as you widen the aperture and the depth of field narrows, the hyperfocal distance will recede..

Based on the numbers you give above: at f/5.6, if you focus at 92 feet, everything behind it to infinity will be in focus. So this would be a good focus point for landscapes. At f/2.8 however to have to focus nearer to infinity (i.e. further from you) to get the same effect..

The hyperfocal distance is primarily for landscapes, as I said above. If you want as much as possible to be in focus, don't focus on infinity, or a lot of the forgeround might be out of focus. If you focus at the hyperfocal distance the d.o.f. will extend back to infinity and also further forwards, giving you more of the foreground in focus as well..

Best wishesMike..

Bengrow wrote:.

Hence why I was thinking I must change lenses to the 17-55 f2.8 toget the blurred results as I just dont seem to get them when usingthe 17-85 f4-5.6..

Ie the apature plays a big part to achieve this??.

Yes, the aperture is certainly part of the deal..

You would want to use the long end of your zoom lens, 85mm, but at the long end, 85mm, all you have is f/5.6..

With the 85mm f/1.8 prime lens you could have both ... 85mm and f/1.8 ... or f/2 ... or f/2.2 et cetera..

Or yes, the f/2.8 zoom...

Ahh. I understand now... Thanks for your good explanation!..