Why stop at f/16

[menos I M6]

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The reason for this is simply a decision, balanced by design.

 

- apertures with a lower number of blades are more difficult to build to accurately stop down evenly at very small apertures (see how vintage 35mm lenses often have uneven distances between aperture stops at smaller apertures)

- apertures with a wide range from very large apertures to very small apertures are very difficult to build in confined spaces (read: compact lenses) - you have to somewhere include space for the translation from a rotating motion into a curve shaped two dimensional motion - those loooooong slots for the aperture pins have to fit somewhere - remember we are talking very compact lenses

- very small apertures with todays high resolution digital sensors are not as desirable and "en vogue" any longer as they have been at the beginning of 35mm photography in the first half of the 20th century - we simply tend not to use them any longer but we use technical cameras when we want deeper DOF, we use todays high end filter system to stop down light to prolong exposure time, we stack focus and have stacks calculated in specific software to extend DOF but retain high acuity of our high res sensors, …

- certain lenses are tended to be used even less at certain aperture ranges (which again plays into the design restrictions - the wider the aperture range, the more difficult, the more compact a lens design, the more difficult, …) Say that 35 Summilux is a lens tended to be used mostly in low light, hence it stops at f16 - you want the very same 35 Summilux but need at all costs an aperture that will stop down at say f32?:

Here is how you get f32 with an ASPH Summilux 35mm: enlarge the lens barrel to say Ø60mm, making space for a larger circumference of the aperture mechanism, add a few more aperture blades as well and lengthen the blade pins and strengthen the aperture guiding cage as to provide sufficient guidance over the longer range of motion

 

Oh wait - there are downsides too - you say you don't like that rattling sound of the aperture? You say you want that aperture NOT to fail when quickly flipping from f1.4 to f32 back and forth and back and forth ? You say you want that aperture to still work in 20 years of use as it worked when you tried the lens in the shop as a young chap?

 

It is all by design.

On my M lenses f11 has been the smallest often used aperture I consciously dialed in, when with macro photography on a SLR I often would choose f22 as of the need of more DOF. I am sure architectural and landscape photographers who use tech cameras will tell stories about f64 - it's the old song about horses for courses I am afraid.

[Peter Branch]

Peter, I've done this experiment and found the effect of diffraction significant.  When shooting landscapes with a close foreground now I use f/5.6 or f/8 and focus stacking.  For a while I was also shooting an f/16 frame to compare and I finally stopped doing that because I almost never ended up using it.  It was always slightly soft by comparison.  Maybe I've tricked myself and the difference is in my head (I never did a blind comparison) but I don't think so.

 

I'm certain that under some conditions with certain subjects it is possible to attribute a loss of clarity / definition to diffraction.

The laws of Physics dictate that the absolute limit of resolution decreases as the aperture number increases.

 

However two things need to be taken into account in in practice:-

Different lenses will be more or less corrected at these small apertures.  It cannot be assumed that the centre of a modern lens is highly corrected  

Digital processing, which easily allows for increases in contrast and degrees of sharpening, has a major influence.

 

I've no idea how the three different DNG files I took were handled in the digital domain of CS6 but whatever the resulting large B&W prints show no visible sign of a drop in resolution. 

 

Whatever the theory, and it was that which was discouraging me initially, in reality f/16 can be a very usable option even for demanding subjects.

Edited February 7, 2016 by Peter Branch

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[jaapv]

Be careful @jdlaing: I was born 66 years ago when nothing seemed to matter, but isn't the term 'piker' or 'pikey' considered politically incorrect these days?

 

 

Cambridge English Dictionary:

 

a ​person who ​avoids getting into ​difficult or ​dangerous ​situations

 

There is a pejorative meaning as well, but I don't think it applies here.

[sdk]

How can it be a problem when Zeiss can provide f/22 on all their ZM lenses? They're like 50-75% cheaper too, depending on the focal length and lens type - compared to the equivalent Leica lens.

 

 

The 35mm/1.4 Distagon ZM only stops down to f/16. Some lenses that perform well at wide and mid apertures perform worse than the theoretical diffraction limit when stopped down past f/8, becoming unacceptably unsharp.

 

I tend to rarely even go to f/16, preferring f/5.6-f/11 for most shots. Sometimes I use f/13, generally with telephotos like the Apo Sonnar 135mm/2 on my D800E, but only when extreme depth of field is really needed.