Why f16 and not f22, etc.

[Krosya]

I was wondering why all (well, maybe most, I don't know , really) Leica M lenses close down to F16 and not more? I noticed that ZM Planar, for example, goes down to f22, while Summicrons seem to stop at f16. Is it that noone uses lenses at f22? Does it have any other effects on image quality?
Any ideas?

 

[Bryce]

Image quality really begins to suffer by f22, at least with short lenses. Diffraction effects cost resolution beyond about f8, so some manufacturers just don't make their diaphragms go that small.

 

[Krosya]

Thanks for your answer. Follow up question - so why some do go to f22, such as Planar ZM? Wouldn't it make more sence to be like other guys and stop at f16?

 

[Bryce]

It is just the manufacturers taking artistic license as far as I know.
I have lenses for 35mm cameras that 'botom out' from f16 to f45.

 

[Jamie123]

I may be wrong but I think it also depends on the lens design. My Hasselblad 150mm lens goes up to f45 while the 80mm only goes to f22.

 

[Mazurka]

I guess we can also expect the following threads soon:

Why do some lenses focus closer than others?

Why don't all lenses have floating elements?

Why don't lenses with the same speed and focal length use the same filter size and focus throw?

Why don't manufacturers make still lenses without over- or under-corrected spherical aberrations so they can have neutral bokeh like cine lenses?

Why does the Noctilux have so much coma even with 3-stop light fall-off?

Why doesn't Leica make the eyepiece as big as the Zeiss Ikon's, or simplify film loading like everyone else since the 1960s, or use variable-magnification finder like the 1950's Canons, or speed up the normal flash sync from >50 years ago?

Why? Why? Why? Why? Why? 😕 😱 :bang: 🙄

 

[Doug]

The aperture diffraction effect is dependent upon the actual diameter of the opening, not the f/stop which is relative aperture. So, for instance, f/22 is three times as large in actual diameter on a 150mm lens as on a 50mm lens, so diffraction isn't nearly as much problem.

 

[Andy Aitken]

Man, you must have the wrong Leica lenses - I have two Leica 90's that go to 22.

and my guitar amp goes to 11...

 

[Magus]

Post deleted by posters request

 

[payasam]

Correct, Doug; but that leaves me wondering why wide angle lenses too generally stop down to f/22 -- like the longer lenses and unlike normal lenses.

 

[Jamie123]

Why? Why? Why? Why? Why? 😕 😱 :bang: 🙄

Because of global warming.

 

[peterm1]

I always get into trouble when I get into this discussion, but....here goes. f stops are a relative size, not absolute. Thus f16 is a different size in a 28mm wide angle lens, a 50mm standard lens and a 135mm long lens. The important point is that even though the "hole" is a different absolute size (if you do not believe me, check by looking at different lenses all set to the same f stop) they let the same amount of light hit the film plane - you see it all depends on the size of the hole AND how far the hole is from the film plane. And for that matter the same goes when you compare 35mm format lenses with lenses designed for medium format cameras. So the long and the short of it is this. An f32 aperture in say a medium format lens would be expected to be a lot bigger than an f32 aperture in a 35mm camera. But diffusion is a function of the absolute size of the hole (not relative size) so you would expect (I think) less image degradation even though you might have the aperture set to f32 (or whatever) Thus you can get away with much "smaller" apertures in certain lenses - eg longer focal length ones, ones designed ofr larger format cameras etc. Whew!

 

[bayerische]

and my guitar amp goes to 11...

But this one goes to Eleven🙂

Spinaltap!

 

[Andy Aitken]

I knew someone would get that!

 

[Silva Lining]

I guess we can also expect the following threads soon:

Why do some lenses focus closer than others?

Why don't all lenses have floating elements?

Why don't lenses with the same speed and focal length use the same filter size and focus throw?

Why don't manufacturers make still lenses without over- or under-corrected spherical aberrations so they can have neutral bokeh like cine lenses?

Why does the Noctilux have so much coma even with 3-stop light fall-off?

Why doesn't Leica make the eyepiece as big as the Zeiss Ikon's, or simplify film loading like everyone else since the 1960s, or use variable-magnification finder like the 1950's Canons, or speed up the normal flash sync from >50 years ago?

Why? Why? Why? Why? Why? 😕 😱 :bang: 🙄

Indeed, do you know the answers?

 

[SDK]

I think the reason some wideangles for 35mm go down to f/22 is to give the user the option of doing landscapes that encompass both very near and far objects, trading huge depth of field for the loss of optimum resolution. If it's not there you can't use it, after all, but you shouldn't use f/22 (or even f/16) unless you really need lots of depth of field.

 

[Mazurka]

Indeed, do you know the answers?

Do we have to know the answers before we ask? 😕

And you can see that Bryce already answered the original question. Doesn't mean it won't be asked again one way or another. 😉

 

[ferider]

I think diffraction, lens application, and aperture shape all play a role.
Wide angle and macro lenses (35 - 50mm) typically go to 22, at least,
with the idea possibly that you have it if you need it, even if you
loose resolution. The compromise of resolution vs DOF is left to the
photographer. My only macro lens has a floating element though and is
quite sharp at f22.

Some apertures are designed to close tighter, and keep a round shape.
For instance the Canon 50/1.2 has a quite original double aperture ring
where one ring closes to about half distance (5.6 or so ?) and then the
second ring closes tighter.

Etc. Part of the lens design and lens character ...

Roland.