Winsor Crosby wrote:
> You could be right, but it seems to me an expensive lens plus filter
> is a very expensive mediocre lens. You might be better off to get an
> inexpensive lens and risk damage.
>
> Look here:
> http://members.aol.com/olympusom/lenstests/default.htm
>
> Put filter in your browser page search function and you will find 4
> or 5 instances of adding filters of varying quality to various lenses
> and how they degrade the resolution.
>
Thanks for reminding me. I only remembered the full 50/1.4 with vs.
without test.
It all makes perfect sense. Only light which passes through at a perfect
right angle to the glass would be unaffected. All other light would be
diffracted to a degree that increases with the variation from 90 degs.
The amount would also depend on the refractive index of the glass. Any
diffraction that varies with incident angle would cause blurring. I
learned all that stuff, theory and calculations, in Physics 1B back in
what seems like a prior lifetime when I was a Physics major at Berkeley.
I'm much more pragmatic now. I know that filters have a small, but
noticeable, degrading effect on the image in many photographic
situations. Therefore, without worrying about precise definition of the
effect, I eschew filters except where they serve a greater image (81
series, polarizer) or protective (welders, mud geysers, etc.) purpose.
Moose
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