Q. re: optimal aperature for sharpness

Started Sep 10, 2005 | Discussions thread
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Eilert Ofstead Contributing Member • Posts: 680
Q. re: optimal aperature for sharpness

Hello all,

I seem to recall (from a previous century) that for each focal length lens, there is an optimum aperature for maximum sharpness at the film plane, and at smaller aperatures, diffraction effects supposedly begin to progressively degrade the image. This issue is (as I recall?) more severe at small aperatures for short focal lengths, whereas with relatively long focal lengths, f22 etc can be used without a problem. (For example, I suspect this is the reason the smallest aperature on my Sony 707 is only f8!!) Since our cameras (Pentaxers) use shorter focal lengths commonly, compared with film cameras, should we be conscious of this issue when using wide angle lenses? And as an example, can someone suggest approximately when (what f-stop) does image degradation begin to be noticeable when using an 18mm (comparable to 27mm film) lens? .....or is this all a non-issue!!!

thanks in advance for input!

Eilert

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