Shooting at f/64

Or whatever the smallest aperture your camera is capable of.

 

I recently read a series of articles about Ansel Adams and Edward Weston and their F/64 Club. Somewhere in the series there was a statement saying something to the effect that this group, including Mr A.A. shot everything at f/64 to insure the most amount of detail in their photos.

 

As I understand it, a lens has a curve to it. So when you are "wide open", you get more or less the entire curve of the lens, and when you shoot at higher f stops (tighter apertures) you shoot only thru the very center of the lens where it is at its flattest. In doing so, one may attain greater "depth of field" at these higher F stops, with everything in focus. Thus recording as much detail as possible onto the film or sensor.

 

As opposed to having a very limited depth of field wide open, with very little, or certain specific aspects within the framed shot, in focus

 

 

Can we discuss this, please & thank you?

I think of it as a cone of light passing through the hole which forms the lens aperture and focusing on the film. The smaller the aperture, the slimmer the cone. In theory the cone needs to come to a point on the film for exact focus to be achieved. In practice the lens, film, processing, printing, the human eye itself all have limited resolving power and it does not have to come to an exact point to appear sharp, rather a tiny circle. The largest circle which still gives an apparently sharp picture is called the circle of confusion. At larger apertures the cone of light becomes broader and there is much less margin for the range of object distances to yield "sharp" results. Hence the larger the aperture, the smaller the depth of field.

 

The problem with very small apertures is that an effect called diffraction causes loss of sharpness. This is because, although most of the light passing through the aperture is focused on the image, light waves passing very close to the edge of the aperture, are bent slightly instead of being focused. It depends not on the relative aperture like F/64, but on the physical diameter and how much bigger it is than the wavelength of light. Adams used mainly large format cameras which have a larger physical aperture than, say, 35mm cameras for a given relative aperture. And the larger format means that diffraction is not as noticeable.

It is highly dependent on the film size. Large format cameras tolerate and often do quite well with very small apertures - which is what Adams and Weston were talking about, not so with more popular smaller 120 films for TLR bodies and 35mm films. Lenses for large format cameras are designed very differently than lenses for much smaller format cameras. With 35mm bodies usually about f/16 diffraction sets in destroying much of the sharpness of the image. If you get a good book on photographic optics it will help place some of your questions in perspective. Erwin Puts, the Leica reference writer for many years, in his Compendium, the text translated into English, which you can occasionally find earlier editions online free, has several chapters on the issues involved in lens design and usage to deal with various factors introducing distortion into the image. It is a difficult read and the math can be a little daunting, but quite illuminating, and it will dispel simplistic explanations which can lead one astray....sort of like telling a child..."you turn on your key in the car and it drives"...not quite that simple.

Lens performance isn't usually a big issue today, but diffraction can be. As John says, it's the actual physical size of the aperture that matters for diffraction. Consider a 4x5 camera with a 210 mm lens (8.268"). f/64 would be an aperture size of fl/f# or 0.129". For a 35 mm camera with a 50 mm lens, f/64 would be a little 0.030" diameter hole. I used to have a digital camera with a very small sensor, so much so that f/8 was about the limit for good sharpness. OTOH, sometimes you'll want to trade a small amount of blur due to diffraction with depth of field or maybe a long exposure time. Don't forget lens extension for macro work- the effective aperture relates to the actual extension, not the focal length. (SCL got in there ahead of my typing- very true!)

My use of depth of field goes with the shot I’m taking and the result I want. I tend to like things in focus, but that’s a preference I will often veer away from for different shots. I lean toward narrative and environmental approaches. Having backgrounds less in focus often provides more of a subject-oriented or subject-isolated approach, which I do less frequently. Naturally, I make those kinds of photos as well, but I’m more often interested in the dynamics of the entire scene and relationships within that scene. What I will utilize, because it can have the natural look of how I see, is an f-stop that allows for a softer background without it feeling out-of-focus per se.

In terms of my own aesthetic opinion, many out-of-focus-background shots work but a lot of them just feel like an effect is being used because it can, rather for any thematic or visual coordination with the content of the shot.

 

The f/64 group was an important movement, both in terms of its visual change and its social engagement. It was a direct reaction to Pictorialism, which helped get photography recognized as an art form and mimicked painting to a large extent in order to get to that point. Adams, Weston, and Paul Strand and Imogen Cunningham before them were wanting photography to come into its own and instead of trying to imitate painting they thought the unique aspects of photography had more realist possibilities. The Depression and social awareness helped move photography toward what felt like a natural inclination toward documentary rather than more “romanticized” work. Public works projects were happening out west as the Depression was ravaging the country, so the West represented hope and optimism and realistically showing these projects became an important function for photography at the time. Photographers were getting involved with workers and fights for better wages. There was a sense in which the f/64 group of photographers actually saw Pictorialism, which they were reacting against, as an oppressive aesthetics much as they saw workers as being oppressed. They were liberating themselves from what they saw as the falsehoods and blind spots of Pictorialism and a society that seemed to have similar traits. They created a manifesto, aware of what that term connoted.

It's way off topic, but the F/64 group's reaction against pictorialism was far from friendly. Ansel Adams is said to have described William Mortensen, a Hollywood pictorialist, as The Antichrist. And they succeeded in pretty much getting Mortensen written out of the history of photography, at least according to the critic A.D. Coleman.

Well, they failed. I've read about Mortensen!

 

BTW, diffraction isn't distance sensitive. AFAIK, it tends to put the same softness everywhere on an image.

 

Most lenses are at their best, near "diffraction limited" just a stop down or so from wide open. Naturally the subject has to be within the DOF, which will be extremely limited if close up.

Well, they failed. I've read about Mortensen!

 

BTW, diffraction isn't distance sensitive. AFAIK, it tends to put the same softness everywhere on an image.

 

Most lenses are at their best, near "diffraction limited" just a stop down or so from wide open. Naturally the subject has to be within the DOF, which will be extremely limited if close up.

You (and I) have heard of Mortenson, but I doubt his prints are in the Museum of Modern Art permanent collection. His aesthetic isn't one that I share, but I think that Ansel Adams, et al were probably over reacting.

When I was a youngster, my father, a photo hobbyist, had a 4x5 speed graphic, a so-called "press camera" of the era. The lens had aperture markings down to, as I recall, f/45 or so. Some years later I occasionally used 35mm (film size) cameras, which could typically only be stopped down to f/16 or perhaps f/22. At the time I presumed that this was a mechanical limitation on these lenses - that they simply didn't have enough movement on the aperture-settling ring to fit in the missing numbers, f/32 and f/45. But in later years, as I learned about the so-called diffraction limit of a lens, I came to the realization that the manufacturers were actually protecting photographers from "overdoing a good thing." In other words, going down to f/45 on a 35mm film camera would significantly degrade the maximum detail possible on a reasonably-sized print, so the makers wisely (?) didn't give photographers the ability to go there.

 

What you'll find, as a general rule, is that the smallest physical apertures available on a lens go along with the size of the film (or sensor). My take on this is that they want you to have some nominal "enlarging capability," say to an 8x10" image, without significant degradation to the finest detail. So a 35mm film image, needing ~10x enlargement, must be able to have very fine detail on the film. A 4x5" negatve, on the other hand, only needs to be enlarged 2x for the same print size; consequently it doesn't "need" such fine-detail capability on the film.

 

As a rule of thumb, the finest detail one can deliver to the film (or sensor) is roughly, as I recall, about 1,800 line-pairs per mm divided by the f-number. A line-pair is seen as a black line and a white line next to each other, this used to be the standard way of defining the ability to "resolve" fine detail on the film (or sensor).

 

If you work out a couple of numbers for both 35mm and 4x5" film, enlarged to 8x10", you can see what happens. Say that you set the 4x5" camera lens to f/45. This limits the finest detail possible on the film to about 40 line-pairs per mm (1800/45 = 40). Enlarging this film 2x, to an 8x10" print, cuts that fine detail in half, to about 20 line-pairs per mm ON THE PRINT. Now, for a 35mm film camera, say that you set the lens to f/22. The finest detail possible on the film is now about 82 line-pairs per mm (1800/22 = 81.8). Enlarging this film 10x, to an 8x10" print, cuts that fine detail by 10x, to about 8 ine-pairs per mm on the print, roughly half of what the 4x5" film produced at f/45. At any rate, this gives you a rough way to compare fineness of detail related to lens aperture.

 

Fwiw, after roughly the 1970s or 1980s, these methods of measuring "resolving power" of a lens or system largely moved over to something known as MTF, modulation transfer function. This is seen as a more representative way of designating the "useful" resolving power of a system.

I had a Pentax 50 mm f/4 macro lens that could stop down to f/32. This otherwise excellent lens was very soft at that setting the one time that I tried it.

The 55mm f/2.8 Micro-Nikkor also goes to f/32, but I'd never use it there.

I read in the Hasselblad Compendium that Ansel Adams shot "Moon and Half Dome" using a Hasselblad 500c & the 250mm Sonnar lens. Wonder what aperture he used for the shot?

Start with John's post and Conrad's first post. For purposes of diffraction, f/64 with a view camera is very different from f/64 with a modern digital camera.

 

There are numerous sources online that will show you for many cameras the aperture at which the image becomes "diffraction limited," that is, the aperture at which diffraction starts and therefore limits the sharpness that can be achieved. However, that does NOT mean that:

 

--the effects are big at that aperture, or

--that your image will appear sharper at a wider aperture.

 

The effects of diffraction are initially quite modest, and the additional depth of field from a narrower aperture may increase the perception of sharpness, offsetting the diffraction (even though the two are optically distinct).

I read in the Hasselblad Compendium that Ansel Adams shot "Moon and Half Dome" using a Hasselblad 500c & the 250mm Sonnar lens. Wonder what aperture he used for the shot?

 

In Camera and Lens, page 26 of the revised 1948 edition, Adams says it was 1/2 second at f/16 on Panatomic-X.

 

My recollection is that the name "f/64" was symbolic, to differentiate them from the fuzzy, everything-out-of-focus pictorialist approach.

ALSO

There is a long-standing debate about whether large format cameras and lenses are less subject to diffraction effects than smaller formats.

 

See LINK

 

Though, I still suspect that the larger format makes the same amount of diffraction a smaller percentage of the larger image (just as LF can tolerate lower resolution lenses?)

 

Here's the latter viewpoint expressed (rightly or wrongly)

Ah, hmmm... Why, if a lens stopped down to F22, (or higher) has diffraction of images shot at that aperture, what is the purpose of even having the capability to shoot closed down so far?

 

Can somebody post an image shown this type of diffraction from f22 or. higher, please?

Many lenses only go to F/16. Long lenses can go to smaller apertures with less diffraction for the reasons already stated. The smaller apertures at least allow the photographer to compromise between, for example in macro work, loss of sharpness due to diffracton, and achieving the desired depth of field.

 

I expect also that it's difficult to make lenses which stop down to tiny sizes, while maintaining accurate aperture size, due to manufacturing tolerances.

Ah, hmmm... Why, if a lens stopped down to F22, (or higher) has diffraction of images shot at that aperture, what is the purpose of even having the capability to shoot closed down so far?

 

Can somebody post an image shown this type of diffraction from f22 or. higher, please?

With fast film (i.e. ISO 1600) and really bright sunlight you might run out of fast shutter speeds (especially on older mechanical cameras) to prevent over exposure. This is an extremely rare problem but it could happen.

The studio strobes I use are a bit "clunky" to dial down the power, and for near work(in the 1:10 to 1:2 range for 35mm) I often need to go down to f/22 or smaller even with a camera set to ISO 100.

 

Of course, as magnification gets higher, it's often a fight to keep as much as I need in focus, so I'm happy to trade off some resolution in favor of DOF.

 

It's painful to see what f/22 or smaller does to an otherwise excellent lens.

 

FWIW, I have a handful of 35mm lenses that will go to f/32. In Nikon land, all of my Micro-Nikkors(55mm f/3.5 and f/2.8, 60mm f/2.8, 105mm f/2.8) stop down that small. In addition, I have several longer lenses that go to f/32, including the old Nikkor-Q 200mm f/4, 300mm f/4D, and 300mm f/4.5 AI. You'll see f/45 on some medium format lenses, including the Hasselblad 250mm f/5.6 Sonnar and longish lenses in other systems.

Why, if a lens stopped down to F22, (or higher) has diffraction of images shot at that aperture, what is the purpose of even having the capability to shoot closed down so far?

 

In Camera and Lens, page 98 of the 1948 edition (revised 1976) (if I may be so brash as to make a book recommendation), Adams says: "[A]s the smallest stops are used, the critical definition on the focal plane may be reduced due to diffraction effects, but the effect of approximate good definition over a considerable depth of field is one of all-over sharpness and clarity."

 

The trade-offs between the sharpest apertures and usable apertures (depth of field) vary from lens to lens.

 

For a given lens opening, the f-numbers that apply to longer lenses (such as used with large format cameras) are larger than those of shorter lenses. Scaling Adams's examples from page 95, for a "normal" 4x5 lens of 150mm, the lens opening for f/64 would be about 2.34mm in diameter. For a 50mm lens ("normal" for a 35mm camera or full-frame digital), a 2.34mm opening corresponds to f/21.3; f/64 would be an opening of 0.78mm.

Can somebody post an image shown this type of diffraction from f22 or. higher, please?

 

You probably wouldn't be able to see it unless you compare to a similar shot at a "better" aperture. The effect is very much like a small focusing error. See my post #9 with respect to the extent of the effect in terms of "resolving power."

 

As a note the limit is based on the idea that there is a limit to how small of a point that light can be focused down to. This smallest "spot" is called the Airy disk after astronomer George Airy, who worked out the mathematical treatment.

 

The concept of resolving power, in terms of line pairs per mm, can be seen as the application of the idea of two Airy disks next to each other - how close to each other can they be before they merge into a single blob of light? In order to "resolve" a difference, meaning to see two distinct points, they must be separated by some distance; a guy known as Lord Rayleigh made some rules known as the Rayleigh criteria. The names should allow you to look things up should you desire.

Go it, Bill. Thanks so much for your super detailed posts. Really appreciate it. I will look around at some of this stuff but I have a basic understanding of resolution, line count etc, and thanks very much.

When we use tiny lens openings like f/22 or f/32 or f/64, the length of the zone we call depth-of-field is expanded. These tiny aperture diameters increase depth-of-field however there is a cost.

 

Well studied by Lord John Rayleigh 1842 ~ 1919 British Nobel prize physics 1904, his findings remain true today. The Rayleigh criterion for theoretical resolving power tells us that the twin demons of diffraction and interference take their toll as we stop down.

 

A table, lines resolved -- thus at f/4 the best a lens can do is resove 320 septerate lines per milimeter. This table is computed using Rayleigh equation for wavelength 589 millimicrons, This is the center color of our visual scale.

 

f/1 1392 lines per mm

 

f/2 696 lines per mm

 

f/2.8 487 lines per mm

 

f/4 320 lines per mm

 

f/5.6 249 lines per mm

 

f/8 184 lines per mm

 

f/11 127 line per mm

 

f/16 87 lines per mm

 

f/22 63 lines per mm

 

f/32 44 lines per mm

 

f/64 22 lines per mm

Pictures are worth a thousand words. So here are some examples shot at mid and small apertures.

 

First a full frame of the subject:

Not a real tiger, but a quality half-tone calendar picture of one!

Here's a crop of the nose area at f/5.6, where you can clearly see the half-tone ink dots resolved:

 

The definition starts to deteriorate at f/16:

 

At f/22 it's a bit worse:

 

And you can't see any dots at all at f/32:

 

Tech data: The printed dot pitch was 6/40ths of a millimetre (0.15mm or about 6 thou") according to my weirdly-scaled measuring loupe. However, there are 4 ink screens used at angles to each other, so the overall dot pitch will vary with the colour and density of the print.

 

I used a sturdy tripod and flash lighting to eliminate any vibration effect.

 

The image was manually focused using magnified Live View.

 

Lens was a Tamron 90mm f/2.8 macro that stops down to f/32, and camera was a 24Mp Nikon D7200.

 

It should also be noted that at close or macro distances, the effective aperture of the lens should be used to determine the degree of diffraction.

 

FWIW. The diffraction effect might actually be useful if you're copying half-tone pictures and moire patterning is an issue. Stop your lens right down and let diffraction work for you as a low-pass spatial filter.

Edited April 1, 2020 by rodeo_joe|1

Pictures are worth a thousand words. So here are some examples shot at mid and small apertures.

 

Good examples to demonstrate the practical effect of the lens apertures.

 

But since this is a "beginner" forum, it's probably worth explaining this paragraph:

It should also be noted that at close or macro distances, the effective aperture of the lens should be used to determine the degree of diffraction.

 

Strictly speaking the f-number of a lens is only correct at, or near, infinity focus. When the camera is focused closer, a conventional sort of lens setup has the lens being moved farther out from the camera. When this happens the lens aperture "seems" smaller from the viewpoint of the film/sensor, and consequently the diffraction becomes more significant. In the case of a 1:1 (same size) macro, a conventional lens has to be extended by one "focal length," meaning twice the infinity-focus distance. In this case, the "effective aperture" would be double the actual setting. For example, if a lens is set to f/32, but then racked out another focal length, then the effective f-number becomes f/64. The diffraction effect is that of an f/64 setting, and the exposure must also be treated as an f/64 setting.

 

Anyway, that is what the "effective aperture" means. It might be significant in rodeo_joe's example. But generally speaking, unless you are doing significant close-up shots, you don't have to worry about it.