PetaPixel

Overcoming My Photo Entekaphobia: The Fear of Shooting at f/11

aperture

Entekaphobia is fear of the number 11. I’m a resolution fanatic. I test every new lens for resolution. For personal use, I’ll choose the lens with higher resolution over the one with creamy bokeh every time. When choosing a camera, I have a (yes, I’m ashamed to admit it, but it’s true) strong tendency to want the most megapixels. I’m a resoholic.

Being a resoholic, I’ve always been somewhat fanatical about apertures. Whenever possible I shoot with the lens stopped down at least one stop to wring the maximum sharpness out of my lens. But I’m always careful not to stop down too far because I was taught, soon after I picked up a camera, that if you stopped down too far the dreaded diffraction softening would kick in.

With today’s high-pixel density cameras, that meant f/8 was as far as I would ever stop down. My mental map of aperture sharpness was like the ancient maps of the world – past f/8 there was nothing but the notation Here Thar Be Monsters. Or the equivalent label in Latin or Olde English, just because that makes it seem much cooler.

Detail from The Carta Marina by Olaus Magnus (1490-1557).

Detail from The Carta Marina by Olaus Magnus (1490-1557).

Go to f/11 and the diffraction monster would come and eat the resolution right out of your photographs. The diffraction monster loves to snack on some tasty resolution. When testing I really never checked past f/5.6 or f/8. That’s where the maximum resolution would be. Any further, and, well, you get it by now.

But I knew there were excellent photographers who shot their landscapes and macros at f/11 or even f/16 because they needed the depth of field. I heard rumors of photographers in far off lands who even actually took photographs at f/22. I considered them sort of like those guys who jump off cliffs in batsuits and fly around for a while before pulling their parachute rip cords. It was fascinating to know people did that, but made me a bit queasy. I was certain the survivors would eventually learn the error of their ways.

But lately, some people like Tim Parkin at Onlandscapestarted opening my eyes (by repeatedly beating on my head). They claimed to be shooting at f/16 and even f/22 with high-pixel-density SLRs, carefully postprocessing their images, and getting very nice detailed results. I shook my head sadly at first, hoping they would come to see the light (pun intended). But then I looked at Tim’s recent article “The Diffraction Limit” and had to admit, their f/22 images didn’t look bad at all.

So I decided it was time to open the closet door and see just how bad the diffraction monster really was.

Preliminaries

Before we get into all of this, let’s remember we’re looking at two simultaneous events when we stop a lens down. I am not going to get into lengthy discussions of Airy Discs, Raleigh Criteria, and other arguments here. You can read about them elsewhere. This is the simple overview of what’s going on.

  1. As we narrow the aperture (higher f/number) diffraction occurs which causes some loss of resolution.
    1. Smaller pixels are affected more than larger pixels since diffraction causes a spread of the point into a disc. A disc of small size might still fit nicely on a large pixel, but might cover two small pixels. The math is mildly complex, it’s not linear, and I’m not going into it more than that.
  2. As we narrow the aperture, the lens resolution increases.
    1. The increase is different for different lenses.
    2. The increase may occur at different rates for the center, middle, and corners of a lens.
  3. Decreasing aperture is sort of a race between these two effects. When we first stop down, the lens sharpening is greater than the diffraction softening. As we stop down further, lens sharpening slows or stops, but diffraction softening continues.

Some Resolution Testing

I’m not one to really believe what I see in online examples; given enough postprocessing an online JPG can look pretty sharp if the lens was the bottom of a beer bottle. I want at least a side dish of numbers or some comparative crops with my reviews, thank you.

I decided our current Nikon lineup gave me a great opportunity to look at diffraction effects. By shooting the same lenses on a D700, D3x, and D800, I can look at full-frame sensors with 12, 24.5, and 36 megapixel sensors. That gives linear pixel densities of 118, 168, and 204 pixels per mm, respectively.

I decided to use 50mm lenses because we have 3 choices that are quite different in how they behave at various apertures. The Zeiss 50mm f/1.4 (the schizoid fiftoid) is very soft and dreamy looking wide open, but becomes razor sharp once stopped down to f/5.6 – it’s like two lenses in one. The Zeiss 50mm f/2 Makro planar is quite sharp even wide open, but seems to maximize it’s center resolution by f/4. The Nikon 50mm f/1.4 G is reasonably sharp wide open, but seems to keep getting sharper the more you stop it down.

So I tested all 3 lenses on all 3 bodies at apertures from wide open to completely stopped down in our Imatest lab.

The Effect of Stopping Down on MTF 50

I started right in the middle of my selections: the Nikon D3x with the very predictable Nikon 50mm f/1.4 G lens. Here are the MTF 50 values in line pairs / image height for the center point, weighted average of 13 points, and average of the 4 corner points. Please note that the plotted average is NOT just the average of center and corners, so if the ‘average’ value is near the center, you know the lens stays fairly sharp in the middle regions, while if it’s nearly as low as the corners the lens falls off rapidly away from the center point.

Nikon 50mm f/1.4 on D3x at various apertures

Nikon 50mm f/1.4 on D3x at various apertures

I have to admit I was a bit shocked. Just as expected, the resolution starts to decrease after f/8, but it doesn’t decrease all that much. Even at f/16 the resolution is still quite a bit higher than it was at f/1.4.

The next step was to see how things look with lower and higher pixel density cameras. So I shot the same lens on a D700 and D800.

Nikon 50mm f/1.4 on D700 at various apertures

Nikon 50mm f/1.4 on D700 at various apertures

I was a bit surprised here, too. I had expected the lower pixel density of the D700 would shift the peak resolution a bit, perhaps to f/11, but that wasn’t the case, although the drop after f/8 did seem less severe.

Nikon 50mm f/1.4 on D800 at various apertures

Nikon 50mm f/1.4 on D800 at various apertures

Things weren’t as different as I expected on the D800, either. The center does seem to peak around f/5.6 with the corners peaking at about f/8, which isn’t surprising. The other cameras show only a slight increase in resolution at the center between f/5.6 and f/8 so it makes sense there would be a bit stronger diffraction effect on the D800. I had really expected more than this. The lens still improves in the corners strongly between f/5.6 and f/8 and the improvement is greater than the diffraction softening.

The message I took away, though, is that diffraction softening is real, it occurs where it is supposed to, but it’s really not as severe as I had thought. Even on the D800 resolution is as high, or higher, at f/16 than it was at f/2.8. At f/11 the resolution is as good, or better, than at f/4. And at both f/11 and f/16 resolution is clearly higher than it was wide open. Perhaps the diffraction monster’s teeth aren’t as long and wicked as I thought.

Some Different Lenses

Diffraction softening is fairly constant, but lens sharpening as the aperture decreases is not. Different lenses behave differently. I compared the Zeiss 50mm f/1.4 and 50mm f/2.0 Makro Planar lenses to the Nikon 50mm f/1.4 G we tested above on all three cameras. In the interest of brevity we’ll just show the graphs for the D3x. The variations for the D800 and D700 were similar to these.

ZF 50mm f/1.4 on D3x (left) ZF 50mm f/2 Makro on D3x (right)

ZF 50mm f/1.4 on D3x (left) ZF 50mm f/2 Makro on D3x (right)

Let’s start with wide open performance. At f/1.4 the ZF f/1.4 lens isn’t as sharp as the Nikon 50mm was, while the ZF 50mm f/2 Makro is sharper at f/2 than either of the other lenses at that aperture. The f/2 Makro has reached maximum center sharpness by f/4 and then slowly loses resolution. The lens doesn’t reach maximum corner sharpness until f/8. The ZF 50mm f/1.4 gets maximum center sharpness at f/5.6 and corners again at f/8 on the D3x. (In the graph above, you can see the Nikon reached maximal sharpness at f/8 for both centers and corners.

The pattern was unchanged on the D800, but on the D700 the two Zeiss lenses center sharpness shifted just a bit to the right – moving to f/5.6 for the 50mm f/2 Makro, with corner sharpness remaining peaked at f/8.

So there is some difference in stopped down behavior with different lenses. Before you ask me to go test this or that, the work has largely been done already at sites like SLRgear.com and Photozone – they show center, corner and edge sharpness at various apertures in their lens reviews.

Yes, I Took Pictures

OK, the numbers surprised me a lot, so I went and did what had to be done. I actually took photographs stopped down to f/16 and even f/22.
Here’s one picture I shot at various apertures (this was on a Canon 6D).

aperturefull

What I saw mirrored what the numbers said I would see. Below are some 100% crops of the white gazebo just off center and some tree trunks near the left edge. I also tried something I was told was possible, but hadn’t really believed. I took the obviously diffraction softened f/22 image and did my best to sharpen it in Photoshop. (By best, I mean about 45 minutes testing different combinations of sharpness and contrast enhancement in 3 layers before getting the results shown below as ‘f/22 sharpened’.)

aperture1

I haven’t tried this kind of sharpening before and was feeling my way along. I’m sure it would be better with practice (I blacked out the large tree-trunk for example and the image is about 1/3 stop darker than when I started) but still I found the results surprisingly acceptable.

One thing I found very interesting is that I could perform what was basically postprocess abuse on the f/22 image to a degree that would have been impossible with one of the other shots. Below, for example, is the f/2.8 image above processed with exactly the same settings I used on the f/22 image. The center crop, particularly, looks like a ‘find edges’ special effect filter.

sharp

I don’t mean to suggest that the postprocessed f/22 image is going to be as good as a nice f/5.6 or f/8 image at all. Rather I’m suggesting it can be improved to a larger degree than they can, making up some of the out-of-camera difference between them.

Does this mean f/16 is my new f/5.6? No, not at all. But I think I may become a lot more aggressive about using f/8 and f/11 when I’m trying for a larger depth of field. I even might use f/16 if absolutely needed. I don’t think I’ll be shooting f/22, though. That’s just a step too far for me.


About the author: Roger Cicala is the founder of LensRentals. This article was originally published here.


Image credits: Aperture by chb1848. All other images by Roger Cicala/LensRentals


 
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  • Mansgame

    Yeah, I didn’t read any of that. I just shoot f/1.4 on my 50 when there is not enough light and/or the DOF calls for it. I shoot at f/2.8 on my zooms when it calls for it but shoot at f/11 or f/16 when doing landscapes depending on the picture. I’ve even been known to shoot at f/22 with macros.

    See, life is not complicated.

  • jajajan331

    professional photograpwer use the aperture they need for a shot…. go ask david noton.
    and when this is f22 they just use f22…. whàt do you shoot that needs to be better then professional photographer? who make a living with their photos? :)

  • http://www.vincentmorretinophotography.zenfolio.com/ fast eddie

    You typed the words right out from under my fingers.

  • Mansgame

    Don’t get me wrong, the technical stuff is important too but unless you’re an engineer at Nikon or Canon (or Ahem, Sony) and you start popping out charts, you’re taking your eye off the prize.

  • siva

    There is just too much here to digest. It could have been a great article.

  • Spark

    TL;DR

    f/8 and be there.

  • hede

    Yeah yeah, every commenter here was apparently born with the knowledge “f/8 and be there” and clearly don’t know why or care to learn because they are too lazy to read long articles. (actually it really is a tad too long…) But please stop giving bad advice to people that they don’t need to know the limitations of their equipment, dammit. Knowing technicalities *is* important. And good pros do know the difference between f/8 and f/11 on their lenses. I know my hyperfocals at 24mm and depending on the foreground subject, I choose between f/8 and f/16 knowing very well how much compromise I’m making by decreasing aperture to increase DOF. You gotta know this stuff and you gotta know why. Read the sh*t!

  • ennuipoet

    I like the cut of your jib!

  • Jake

    What confuses me here is his point about the final photograph. He basically says that shooting f/22 allows him to do 45 minutes worth of PP sharpening, which he couldn’t do on the f/2.8 shot because it was too sharp already.
    So basically he enjoys PP sharpening? Isn’t it generally better to have the sharpest image first and minimize post-work?

  • onan

    diffraction is also the new AA filter

  • Pfff

    Poor guy, He must really hate photography. Let me guess, he always shoots at ISO 100 also??

  • Robert

    “Sharpness is a bourgeois concept” – H. Cartier Bresson

  • http://www.easy-snap.com/ yoJoebosolo

    Great article, but the technicalities of defraction mean so little if youre taking photographs of muddy lakes on a cloudy day with a background of grey trees.

  • http://www.facebook.com/banan.tarr Banan Tarr

    This basically tells me I can use whatever aperture I need to achieve the depth of field I want. Thx! (I have a D800)

  • http://twitter.com/darkmavis1980 Alessio Michelini

    Most of the times I shoot my long exp landscape I stay between f/16 and f/22, not because I like it but because I have to use that apertures to archive long exp times

  • http://twitter.com/CAKIR_T Tolga Çakır

    f8 is always and under all conditions optimal

  • http://www.facebook.com/chetan.crasta Chetan Crasta

    Very informative, especially the graphs. Thanks!

  • Hedge

    Just choose the right aperture for the scene, SIMPLES

  • Ken Elliott

    For some – perhaps. For someone like me, I’m grateful that Roger shared his research. Those of us who own large printers (mine is 44″ wide) are far more demanding than most. My printer really wants about 200MP for the largest prints, but I have to make do with just 36MP from a D800. Other photographers mention that they are impressed with the sharpness (and perhaps nothing else) of my prints, and details like this make a real difference.

  • Mark

    I don’t remember the phenomena of f-stop limitations, perfect sharpness etc prior to modern digital cameras. I wonder if the marketing attack is positioning sharpness, megapixels count, and other secondary features as the only factors that define a good photographer…”the tool is the photographer”?…Perhaps because those obsessed with the tool lack appreciation of the end result, the photograph, with all its imperfections (I still find film grain and old lenses make the best photographs, far more character than clean, clinical, perfect digital photos).

    DLSR owners seem to be striving for the perfect tool and perfect result (aided by the tools to investigate perfection…Photoshop zoom), realizing they are again underprivileged and imperfect human beings every time a new camera model is released. How ridiculous all this f8 nonsense sounds. It’s like owning a Porsche but never going above 50km/h on an empty German Autobahn to minimize fuel consumption. If the objective is to minimise fuel consumption, don’t drive a Porsche, get a bike! If you want to make good photographs, use the camera and ALL it’s functions to the full. The benefits easily outweigh the imperfections.

    Apature and shutter are THE control elements. Limiting to f8 is absolute imperfection in the use of such a great tool, and is also the perfect way to miss the best photograph.

  • Cochese

    Perhaps you’re overthinking your work or your processing is off. We’ve got an Epson 11880 (64″) printer here and have done seven foot panoramas from an iPhone image that looked great (Though, the iPhone’s dynamic range leaves a lot to be desired). While a Nikon D800 is the new body here, most of the prints on our gallery walls are from much lower resolution cameras ranging from 8MP to my 18MP Canon 7D. While resolution is obviously important when you’re doing six foot by four foot gallery wraps or huge panoramas, you would be surprised by how large you can print with a lower resolution image that is sharp from the beginning. For the record, I typically shoot around f/8-f/11, ISO100 unless drastic situations are at hand.

  • Cochese

    That all depends on how much of your scene you want in focus and what it is that you are shooting. If you’re looking for as much background detail as possible, you’re not going to get anywhere at f/2.8. Well, depending on your subject and background distance.

  • Cochese

    That f/8 nonsense predates modern DSLRs. But I agree, many photographers focus too much on the gear and not enough on the results. However, you have to realize that an art photographer is not the same thing as a normal photographer. Normal photogs require sharp and clean images to get their work published. From sporting events to senior photos. The more clean and sharp the image, the better. For people like me, who is a little bit of both, it doesn’t really matter the gear if I’m doing something artistic (though, it is really nice to have a lot of resolution so as to not lose anything when I make very large prints). But when I’m shooting a wedding, or portraits, or senior photos, if my images aren’t sharp and clean, you’ll know. Most people aren’t looking for artistic wedding shots, they are looking for professional and clean documentation of their event.

  • Ken Elliott

    Cochese wrote “We’ve got an Epson 11880 (64″) printer here and have done seven foot panoramas from an iPhone image that looked great”

    I suspect you and I have different standards for “looked great”.

  • Cochese

    Sharp and focused where need be and superb color reproduction. What more are you looking for in a print? Aside from archival quality fine art papers and canvas’ for prints, I can’t imagine they would look anything but. There’s a reason we produce fine art reproductions for the majority of the painters in the area and ship prints as far as Abu Dhabi and South Korea.

    We all have different things that we look for in image quality, but in the end, we mostly look for the same thing. Seriously, who wants a dull, noisy photo? Well, unless it was meant to be that way!

  • hyungsup Kim

    “f/8 and be there” is not even about limiting oneself to using just f/8. HCB probably said it to simplify the job. And f/8 at any focal length provides a “normal to wide” depth of field for any given focal length which is ideal for the job HCB was doing. As a Leica user myself, (and probably any manual focus camera user would agree with me) f/8 is great because you don’t have to focus the subject super critically to get it in focus which is great for photojournalism because of moving subjects and fast changing sceneries. Also if I heard correctly the first non-collapsible summicron, which he was using, f/8 was the sweet spot, so he probably thought 2 birds in one stone, so why not. If HCB was a portrait photographer he might have said, f/4 and be there or f/5.6 if addressing the issue of sharpness. Who knows. And me, as a student photojournalist/street photographer, use his guidelines and use f/8 when I’m outdoors and I just have to think about shutter speed, which simplifies the process a whole lot. you don’t have to think about aperture or any thing just shutter speed value, and sometimes just think about stops not even real values.