blur background

[pbosco]

i have a canon a570IS and im trying to get pics with "blurred background".

any someone offer tips in lament terms please?

the manual states :

Av Setting the Aperature

selecting a lower aperature value allows you to blur the background and create a beautiful portrait. a higher aperature value brings the entire range from foreground to background into focus.

aperature values range from F2.6 to F8.0

i have tried to no avail... what should the settings be on to get these types of pics right? maybe im not focusing correctly on a subject?

[Alan T]

pbosco wrote:

aperature values range from F2.6 to F8.0

To get a sharp image over a wide range of subject distances, you need to let the light through only a tiny hole (aperture) in the lens. You're aiming to imitate a 'pinhole camera' where you have no glass lens at all, just a tiny hole. This doesn't let much light through,so it's not a very practical camera.

Conversely, to get subjects at only one distance sharp, and everything else fuzzy, you need a big hole, a large aperture.

"F8.0", which should really be written "f/8.0" is a small hole, one eighth of the focal length of the lens. If you have a focal length of 8mm, it's a 1mm hole, letting in only a little light. Mostthings will appear as sharp as your technique permits. We say you have a "large depth of focus"

"F2.6" (f/2.6) is a large hole. On an 8mm focal length lens it will be a 3mm hole, letting in 9.5 times as much light. Only a narrow band of subject distances around the thing on which you focus will be sharp. If you focus on something nearby, the background will be out of focus, which is what you want in this case. You'll have small depth of focus.

Unfortunately for users of compact digicams, like you and me, the size of our image sensor is rather small, so we've always got quite a small hole in our lens, for any given f-number, compared with old-fashioned film cameras, and dSLRs, and especially antique plate cameras - a 'whole plate', effectively the sensor, is 8.5 x 6.5 inches, not our tiny few mm. So the smaller the camera, the greater the apparent 'depth of focus' for given settings.

This is because the apparent depth of focus when you finally view the image depends on the relationship between the original subject and the viewed image, asseen through that particular size of hole, be it tiny (at any aperture on a digicam) or huge (at any aperture on a plate camera).It has nothing to do with the size of the equipment used to produce a tiny replica image of the subject and then blow it up again for viewing at a convenient size. But it does depend on the size of the hole that the equipment used.

So, on your camera, get close to that subject, so that the background is a long way away,use f/2.6, and focus carefully on the bit you want to see sharp.

If the background is still too sharp, you'll have to buy a bigger, more expensive & inconvenient camera, with a bigger maximum aperture lens, e.g., f/2.

Good luck!

[Alan T]

...or you could consider using an image editor (Paint Shop Pro, Photoshop, etc), carefully selecting the sharp bit, and artificially digitally blurring the rest. This will be a lot harder than using f/2.6

[TCav]

I believe the A570IS has a Protrait mode that does exactly what you want. Have you tried that?

[pbosco]

Alan T wrote:

...or you could consider using an image editor (Paint Shop Pro, Photoshop, etc), carefully selecting the sharp bit, and artificially digitally blurring the rest. This will be a lot harder than using f/2.6

that to me is actually easier method.. using photoshop (which I know how to use well) i just select the background and add the blur filter.. works good.

[pbosco]

TCav wrote:

I believe the A570IS has a Protrait mode that does exactly what you want. Have you tried that?

yes I have tried Portrait mode, but no luck.. when you have it on Portrait you cannot adjust the aperature size, can you?

[TCav]

pbosco wrote:

TCav wrote:

yes I have tried Portrait mode, but no luck.. when you have it on Portrait you cannot adjust the aperature size, can you?

I don't know for a fact, but it would seem to me that 'Portrait' mode would open the aperture to the maximum without you having to do anything.

But you should be able to use the Aperture Priority (Av) mode, to set the aperture to whatever you wanted, and let the camera select the shutter speed.

[pbosco]

i'll play around with it more.. seems like using MACRO will get the effect almost to work right.

Av lowest setting is f/2.6... i dont see how to adjust the shutter speed in this mode too. can I?

does the IS have anything to do with it? should it be OFF, continous, panning? right now its set to continous mode.

[TCav]

pbosco wrote:

Av lowest setting is f/2.6... i dont see how to adjust the shutter speed in this mode too. can I?

Yes, f/2.6 is the maximum aperture for the A570IS at its widest angle. In the Av mode, you select the Aperture mode, and the camera selects the shutter speed for a properly exposed photo.

[msantos]

What you want to get is not easy with small sensor cameras (point & shoot), but anyway you can do it. As you said, set aperture to minimum number (max aperture), and .....

go some steps backwards from your subject, setzoom to max, and voila!!!! :|