F-stop Sweet Spot

I read recently that the best F-stops for lens both camera and enlarger are F8
and F11. I realize that depth of field comes into play, so putting that aside
how does F22 suffer in either cameras and/or enlargers.

If the sweet spot is F8 what do I lose with my camera when I have it set at F22
aside for longer exposures?

If the sweet spot is F8 for my enlarger what are the costs at F2.8 or F22?

Are the differences perceivable?

Does the complexity of lens factor in here?

"ATIPPETT" wrote in message
...
I read recently that the best F-stops for lens both camera and enlarger
are F8
and F11. I realize that depth of field comes into play, so putting that
aside
how does F22 suffer in either cameras and/or enlargers.

If the sweet spot is F8 what do I lose with my camera when I have it set
at F22
aside for longer exposures?

If the sweet spot is F8 for my enlarger what are the costs at F2.8 or F22?

Are the differences perceivable?

Does the complexity of lens factor in here?

The sweet spot depends somewhat on the size of the lens. For example, on a
large format lens with largest aperture of f/8 and minimum of f/64, the
sweet spot is closer to f/22. On my digital camera, which has an f/2 lens
with minimum aperture of f/8, the sweet spot is closer to f/4.

For MF lenses, the sweet spot probably is close to f/8 or f/11, but it does
depend on the lens. This partly determined by the design of the lens.

Another important factor is the inherent fact that all lenses suffer from
diffraction limitation when stopped down, which means as the aperture gets
smaller, the theoretical maximum resolution of the lens decreases. Do a
google search on diffraction limitation for more info.

As you mentioned, the smaller the aperture, the better the focus is at the
film plane and the better the depth of field of the subject matter.

Schneider has some good MTF charts which document the sweet spots on their
enlarging lenses:
http://www.schneideroptics.com/photo...oto_enlarging/

There are often diffraction effects at very small apertures (f22 +) with
multi-element lenses.
Most f2 camera lenses seem to look best at f5.6.

Every lens is different. Test yours and make your own choice.



"ATIPPETT" wrote in message
...
I read recently that the best F-stops for lens both camera and enlarger are F8
and F11. I realize that depth of field comes into play, so putting that aside
how does F22 suffer in either cameras and/or enlargers.

If the sweet spot is F8 what do I lose with my camera when I have it set at F22
aside for longer exposures?

If the sweet spot is F8 for my enlarger what are the costs at F2.8 or F22?

Are the differences perceivable?

Does the complexity of lens factor in here?

ATIPPETT wrote:

[...]
Does the complexity of lens factor in here?

Absolutely!

While some lenses may indeed perform best at, say f/8, others will not. Some
even will perform best fully opened.

What happens, always, with every stop that a lens is closed down is that
maximum achievable resolution is reduced. About halved every two stops a
lens is closed down. Diffraction is the cause of that.

So would we be dealing with diffraction only, all lenses would perform best
wide open.
Alas, most lenses are troubled by all sorts of faults, reducing resolution
too. The effects of these aberrations are lessened by stopping down (using
more and more of the central bit of the lens, which shows least faults).

So stopping down is a balancing act: while the aberrations are reduced,
limiting the resolution limiting effect of those, the limiting effect on
resolution by difraction increases.
So as long as aberrations are worse than diffraction, stopping down
imporoves resolution.

How far a lens must be stopped down to reach that point depends, of course,
on how much lens faults there are. And that is a matter of lens design.
And since not all lenses are created equal, a "rule" like the "f/8 sweet
spot" thingy is rather, well... useless.

db wrote:

There are often diffraction effects at very small apertures (f22 +) with
multi-element lenses.

Diffraction is always present, and it gets worse the same when going from
f/16 to f/22 as it does from f/2 to f/2.8.

And i'm afraid it's not restricted to multi-element lenses either.

In article ,
ojunk (ATIPPETT) wrote:

I read recently that the best F-stops for lens both camera and enlarger are F8
and F11. I realize that depth of field comes into play, so putting that aside
how does F22 suffer in either cameras and/or enlargers.

If the sweet spot is F8 what do I lose with my camera when I have it set at F22
aside for longer exposures?

If the sweet spot is F8 for my enlarger what are the costs at F2.8 or F22?

Are the differences perceivable?

Does the complexity of lens factor in here?

You know, I think those standards are over rated. I have shot 10,000
plus images in my 22 plus years. I can attest that 35mm f/22 negatives and
slides are sharper than f/8 for exosures in camera,....a good aligned enlarger set up properly
will give you a sharp print regardless of apeture on the lens,.....but a good lens is essential.
No fricked up elements, or milky optics.

You know what come to think of it 400 asa film is alot sharper at f/22 than 100 at f/5.6
--
Duzz that A moose you ?

In article ,
"db" wrote:

There are often diffraction effects at very small apertures (f22 +) with
multi-element lenses.
Most f2 camera lenses seem to look best at f5.6.

Hum????? How to respond to a general statement?????Hum?
If you like shalow DOF? Something missing "L" :-D
--
Duzz that A moose you ?

"RSD99" wrote:

Every lens is different. Test yours and make your own choice.

With my Mamiya 645 lenses and a 60x microscope, I could _maybe_ persuade
myself that wide open and f/22 were _slightly_ worse than the other f stops.

The "sweet spot" bit is more of an issue for people who shoot test charts
than for real photography.

David J. Littleboy
Tokyo, Japan

Any Moose Poster wrote in message ...
snip

You know, I think those standards are over rated. I have shot 10,000
plus images in my 22 plus years. I can attest that 35mm f/22 negatives and
slides are sharper than f/8 for exosures in camera,....a good aligned enlarger set up properly
will give you a sharp print regardless of apeture on the lens,.....but a good lens is essential.
No fricked up elements, or milky optics.

You know what come to think of it 400 asa film is alot sharper at f/22 than 100 at f/5.6

Um, are you sure? I ask because my 55/2.8 and 105/2.8 MicroNikkors,
both bought new in 1986, are noticeably sharper in the plane of best
focus at f/8 than at f/22. In fact, the 55 is best in the plane of
best focus below 1:1 at f/5.6 and reversed above 1:1 at f/4. I shoot
them at apertures smaller than f/8 only to gain depth of field.

Could you be confusing sharpness in the plane of best focus with
sharpness in depth? We give up some sharpness in the plane of best
focus to get more DOF, but every lens has an aperture beyond which
stopping down loses sharpness overall.

Cheers,

Dan