Aperture stuff

[Ari Pesonen <ari.pesonen@xxxxxxxxxxxxxx>]

 Murray White wrote:

>        Willem- this seems a bit confusing. What is highest opening? Is it
>not preferable to speak in terms of widest and smallest aperature. Does
>highest mean smallest opening, largest # ie f22 or because you use the term

I'm sorry that I mix in this, but it should be clear that a wide aperture
means a big hole and a small aperture a small hole, because the whole
word "aperture" comes from Latin's "apertura", which means "opening".
So, the widest opening is widest, and vice versa.

Besides, the numbers are fractions, just like the speeds:
Ap. 2=1/2 ... 16=1/16 of the focal length. The best aperture considering
diffraction and such things depends on the real diameter of the aperture in 
millimeters (or whatever measurement unit), not the relative opening.
This means that in a large camera with a long focal length you can use
smaller relative aperture without disturbing diffraction.

Conclusion: 1/2 is a higher number than 1/22, which means that 2 is a higher
aperture than 22. Q.E.D.

Greetings,

Ari Pesonen


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Topic No. 7