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Old Sep 21, 2007, 9:32 PM   #1
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what would you consider to bethe sweet spot aperture
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Old Sep 22, 2007, 7:21 AM   #2
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Most lenses for 35mm cameras and dSLR models are sharpest about 2 to 3 stops down from wide open.

But, because of diffraction limitations with a smaller lens design you see on current non-DSLR camera models, you usually need to stay at much larger apertures (smaller f/stop numbers) with them.

That's mostly because the actual focal length of the lens is very short on a non-DSLR camera model like this, and the actual aperture opening becomes quite small.

Aperture as expressed as f/stop is a ratio between the focal length of the lens and the area of the aperture iris diameter. So, the smaller aperture opening can cause some diffraction issues if you try to close it down too much on this type of camera.

That's one reason why most lenses for 35mm camera have apertures of f/22 or smaller available. Yet, most non-DSLR cameras are limited to around f/8 or f/11.

You have much greater depth of field for a given aperture and framing on a non-DSLR model anyway, because you have a narrower angle of view (more apparent magnification) for a given focal length, and Depth of Field is based on the actual (not 35mm equivalent) focal length.

The actual focal range of the lens on the S5 IS is only 6-72mm (which gives you the same angle of view/apparent magnification you'd have using a 36-432mm lens on a 35mm camera).

See this handy Depth of Field Calculator to get a better idea of how that works:

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

I'd probably try the S5 IS at around f/4 on the wide end of the lens and see what you get there. If you're zooming in more, it may be sharpest another stop down (probabably around f/5.6 on it's long end).

If you want to find out for sure, you may also want to try taking some test photos at different apertures and zoom settings to better judge the characteristics of the camera at various focal lengths and apertures.

But, I doubt you're going to see a big difference in sharpness between the available aperture choices (although you'll get greater depth of field if you use a smaller apeture, represented by a higher f/stop number).


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Old Sep 22, 2007, 1:44 PM   #3
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thanks for that dof master

i did realize fom my pics that when the camera was set on auto it mostly selected between 2.8 & 4 which came outgood and those i manually set on 8 came out not so good
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Old Sep 22, 2007, 2:23 PM   #4
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Yes, most non-DSLR models will stick to the wider aperture settings in their Auto mode unless shutter speeds are relatively fast (i.e, brighter conditions).

More light gets though at the wider aperture settings. So, that allows you to use faster shutter speeds for any given lighting and ISO speed (which helps to reduce blur from camera shake and/or subject movement).

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