Aperture....?

[Fireblade2K4]

I've been trying to use my camera now for a while on Manual to try and get the most from it (Canon S3 IS) but don't fully understand what the Aperture (f2-8) does apart from make the image darker.

Can someone explain this to me please, what it does, why I need to alter it and benefits of using a low aperture as opposed to a higher one or vice versa.

Everything else I'm ok with, shutter speed, exposure, ISO just aperture, thanks in advance.

Stu

 

[philio16]

Bit of a new learner myself here but aperture also effects depth of field I think!

 

[Gregeff]

Apeture:- How wide the hole in the lens is.

Wide Apeture: - Small F Number, Eg F/1.4. Lets more light in, so a faster shutter is possible. Small Depth of field.

small Apeture:- Large F Number, Eg, F/16, Thus lets less light in, produces a much larger depth of field.

So, use a Wide Apeture in dark conditions or when you want to seperate the subject of a photo from the background. Use large Apeture in good light to make most of the picture be in focus.

Also when wide open lenses tend to perform worse because the optics of the lens are working at there limit. Also at the other end of the scale with very small apetures the picture quality often lessens due to defraction. Thus for the sharpest photo's an Apeture of about F/8 is often best.

The F number asociated with Apeture is actually a fraction of the focal length of the lens. So a 50mm lens at F/1, would mean that the apeture of the lens has a diameter of 50mm. Thus at say F/2. The diameter of the apeture would be 25mm. Each stop increase of F number , Eg, F1.4-> F2. Halves the area open of the apeture, thus halving the amount of light going through the lens, which is why you need to double the amount of time the shutter is open for to get an equally exposed photo.

 

[Joe T]

^^^ what he said.

 

[nolimit]

just shoot the same object with all aperture level while adjusting the shutter speed to get similar exposure.
You will see how it affects your photos.
'm not sure if Canon S3 has A mode. if it has use the A mode to try the Aperture levels and camera will take care of the shutter speed.