Garry Lewis wrote:
> From an otherwise interesting article--
>
>>At f8, a lens it theoretically capable of resolving 94 lp per mm. At f2,
>>the same lens is >>theoretically capable of 385 lp per mm.
>
>
> Does not compute!!
-------------------------------
The theoretical resolution of a lens is based on aperture. The larger
the diameter of the lens the greater the resolution... think telescope.
Here the statement makes it appear that resolution is based on focal
ratio which is not correct. However, for a given lens it's true that
the diameter of the lens is larger at smaller focal ratios. So,
theoretically a given lens should resolve more at f/2 than f/8. But we
all know there's sometimes a long reach between theory and practice.
BTW, for earth based telescopes, the practical resolution limit is
reached somewhere around 12". Any bigger than that and atmospheric
turbulence destroys the resolution advantage of the larger glass.
However, the larger glass will always gather more light.
Chuck Norcutt
==============================================
List usage info: http://www.zuikoholic.com
List nannies: olympusadmin@xxxxxxxxxx
==============================================
|