Practical examples of stopping down and diffraction (was: Re: Konica IR ...!st time, hyperfocal focusing, and Stigmata)

[Marco Pauck <pauck@xxxxxx>]

> Well, you'd be surprised. For some unknown reason, I used to use the same
> terminology, AND had the same intuitions (or have been taught like that?), that
> the smaller the apperture (i.e. the greater the f number) the better the
> image....

In order to support (and maybe close) the theoretical
discussion with some real-world examples, have a look at:

http://www.pauck.de/marco/photo/stuff/comparison_of_quality/comparison_of_quality.html

You'll see that the lenses compared have their best
optical performance around f8-16. The Yashinon suffers
from diffraction at f32. These values are for the visible
part of the spectrum. For the near-infrared you shold
probably open the aperture at least one f-stop.

	Marco
--
Marco Pauck -- marco@xxxxxxxx -- http://www.pauck.de/marco/
For every complex problem, there is a solution that is simple,
neat, and wrong.  -- H. L. Mencken
*
****
*******
******************************************************
*  To remove yourself from this list, send:          *
*         UNSUBSCRIBE INFRARED                       *
*       to                                           *
*         MAJORDOMO@xxxxx                            *
*----------------------------------------------------*
*   For the IR-FAQ, IR-Gallery and heaps of links:   *
*  http://www.a1.nl/phomepag/markerink/mainpage.htm  *
******************************************************