Bipod

"Light passing a sharp edge (such as the aperture blades in a lens
hsa the property of bending slightly around the edge, an effect
known as diffraction..." -- Ansel Adams, The Camera, p.76.

Adams didn't have to worry about diffraction too often--he shot mainly
large format, where forcal lengths are quite long--and aperture diameters
correspondingly large. He goes on to say, "In practical photography, this
effect is significant only at the smallest apertures; the light passing the
aperture blades is slightly spread and diffused, casuing a reduction in
image sharpness." (op. cit.).

Adams and Willard Van Dyke were the co-founder of the famous "Group f/64"--
so named because on a large format camera, f/64 is sharp with enormous depth-of-field.
Other members included Imogen Cunningham and Edward Weston.

On a 300 mm lens (the "normal" lens for an 8" x 10" view camera), f/64 is about
as large as f/11 on a 50 mm lens! So on on Adams's big view camea, f/64 was
as sharp as our f/11.

But photographers who shoot miniature format have to worry very much about
diffraction. On a 50mm lens. f/64 would be about the size of a pencil lead--way
too much diffraction to be usable. Our narrowest aperture is f/22 --which is
only 2.27 mm in and decidedly unsharp.

How is it possible for people who shoot minature format ("full frame") or smaller
never to have noticed that f/22 is unsharp on any lens shorter than about 100 mm?

Apperantly there are a lot of digitotgraphers who never really look at their images
except on dinky LCD screens. "Hey, this thumnail looks pretty sharp to me!"
And they never make prints. And they never bother to magnify and look to see
whether detail is present or missing.

Otherwise, how can we explain people not knowiing this basic fact of photography--
Which was not to Henry Fox Talbot? And a fact of optics that was well known to
Huygens and Newton in the 17th century?

Diffraction matters because these little cameras are capable of making pretty good
prints at 8" x 10" or a bit larger--but not if there is excessive diffraction. If you
shoot at f/22 or even f/16 and plan to make a large print, you just shot yourself in
the foot.

Of course, not all subjects or styles need sharpness--but most do.

That people can argue for pages about something that isn't the least controversial--and
that is covered in nearly every book ever written about about photography--is truly
depressing.

TriX Loc: Raleigh, NC

Couldn’t agree more. When I set the speed control on my car it will do the same thing going downhill - love it!

bpulv Loc: Buena Park, CA

Something I never considered before.

Bipod

One upshot of this discussion of optics: format matters

Smaller format:
* Faster lenses (for a given type, e.g., "normal".)
* More diffraction (for a given f-number)
* Fewer usable f-numbers
* Capable of less depth-of-field (for a given lens type)
* Smaller sensor/film area = less resolution possible

Larger format:
* Slower lenses (for a given type, e.g., "normal".)
* Less diffraction (for a given f-number)
* More usable f-numbers
* Capable of more depth-of-field (for a given lens type)
* Bigger sensor/film area = more resolution possible

Choices available right now range from 1"x1" sensor to 8" x 10" film
(80 times more area).

You pay your money, you take your choice There is no single "correct" answer--
it depends on subject, lighting, location, your style and how you intend
to display or print the image.

But know this: nothing on earth can give a sub-miniature format (i.e. less than
"full frame") camera the resolving power of a miniature format ("full frame").
The former has more diffraction and less sensor area. (But it can have a
faster lens, be lighter, smaller and less expensive.)

And nothing on earth can give a miniature format ("full frame") camera the
resolving power of a medium format (.e.g, 120 film camera) .... let alone a
large format (4" x 5" or larger). Or the depth-of-field.

And that is without getting into the pixel density of a sensor vs. silver
halied crystals in an emulsions or on a sensitized surface.

The highest resolution photographic process known is daguerreotype.
A digital copy can only capture a tiny amount of the astounding resolution
of an original daguerreotype (made with a modern lens):
https://prisonphotography.files.wordpress.com/2014/11/bd-thetransamericapyramid-copy.jpg

If newer were always better, then the worst US President would be Geroge Washington
and the best would be....