A stupid question: sharpness/resolution vs focus

Started Nov 27, 2005 | Discussions thread
beerguy Senior Member • Posts: 2,539
Re: A stupid question: sharpness/resolution vs focus

Gediminas 8 wrote:

beerguy wrote:

I would never leave the tripod at home - no hand-held image is as
sharp as one shot using a good tripod, disregarding IS. It's also
tough to guarantee a straight horizon hand-held.

I partly agree on the horizon part. On the other hand, not all
tripods are equipped with spirit levels, which means there's little
or nothing to be gained in that respect from using one.

For landscape work you should be using some sort of level, at a minimum the small spirit level you stick in the cameras hot shoe.

I find it difficult to believe the 10-22 is that bad-I've used it
and been extemely pleased with the images, and I tend to shoot at
at least f/8.

Where did I say that it's bad? I love mine:) I was only referring
to the effect of diffraction on resolution (of any lens) - in the
case of the 10-22, the effect has been found to surface from f8
upwards (see
http://www.photozone.de/8Reviews/lenses/canon_1022_3545/index.htm ).

Looking at the test data, the diffraction effects seem to be fairly minimal. I wouldn't expect to see much impact on image quality, at least in a print. Pixel peeping is another story.

A detailed explanation here:

http://www.cs.mtu.edu/~shene/DigiCam/User-Guide/950/depth-of-field.html

Thanks for the link. However, it doesn't quite answer my question,
which was: if diffraction deteriorates the sharpness of a lens, is
there any point in using the lens for landscape work, say, at f16?
The positive and negative effects of a stopped-down aperture would
seem to cancel each other out.

It just a matter of finding the sweet spot for a given lens. If the lens starts to exhibit diffraction at f/8, then maybe you only stop down to f/11, and then only when needed. I typically shoot between f/8 and f/11 with most lenses anyway, unless I'm looking to blur out the background. Sometimes I shoot at f/16, but only if necessary. And I suspect that you would be hard pressed to see diffraction effects in a print, anyway. Many things that can be found on an optical bench are not really noticeable in real shooting situations.

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Cheers,

bg

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