Tutorial: Aperture and Art
story with photos (32 photos) starring Ariel Anderssen
This is the second in the series of bonus tutorials from the one-on-one tutorial session Ariel and I ran for RE member-turned-photographer Paul McRope. Many thanks to Paul for generously allowing us to share the photographs he took on the day with you.
In the first series, we learned that the most important choice you make is the lens you choose to image the scene with, and that the most important factor within that was the focal length of the lens.
In this series we learn the artistic impact of the second most important facet of lens selection- lens aperture.
The aperture of the lens is, simply speaking, how big the hole you open up to allow the light through is. All lenses have a maximum aperture, which is where the light from the whole lens is allowed to pass through the lens to the sensor. Within the lens mechanism there's a series of sliding blades which can restrict the size of the hole.
It is fairly obvious that this will control the amount of light getting through to the sensor. It's completely non-obvious why the aperture blades have to be in the middle of the lens and why sliding them in and out changes the character of the image in a very dramatic way. It's even less obvious why the way we specify the size of the hole is in arcane "f-ratio and f-stops".
Fortunately, we don't need to understand the physics of imaging. We need to get a gut feeling for what the artistic impact is on the image of choosing a certain f-number setting for your photo is.
For that, we just need to know that small f-numbers mean a big hole, letting in lots of light, and also means a shallow depth-of-field, so only a small portion of the whole depth of the scene will be rendered in focus on the camera sensor. Large f-numbers mean a small hole, letting in much less light, and also means lots of depth-of-field, so much more of the whole depth of the scene will be in focus, from objects in the foreground right through to objects in the far distance.
But even that's too abstract to really grasp what twiddling that f-number aperture dial on the camera really DOES to the image.
So let's do it. Let's shoot those same two shots- a full-length shot and a head-and-shoulders portrait. Let's do it with two "standard" bondage photoshoot focal length lenses- a 35mm and an 85mm. Let's start at f/16, which means the hole is as small as possible on these lenses. And let's do it at the standard "one stop" intervals, so f/16, f/11, f/8, f/5.6, f/4, f/2.8, f/2, f/1.4.
I'm not going to exhaustively go through each shot; notice that the difference between adjacent shots is subtle, but the difference between f/16 and f/1.4 is radical. What's the nature of the difference? I'll point out a few of the highlights. You might want to zoom in to the full versions of the shots to really get the subtleties, it's a bit hard to see on the web-sized normal pics. Sorry for the one or two messed-up shots, we were shooting the series and missed focus entirely on one or two, but you get the jist.
At f/16, the whole world is in focus on the 35mm focal length shot. We can see as much detail in the twisting of the wires on the telegraph pole as we can on the stitching on Ariel's dress or on Ariel's hair and eyelashes - actually probably a bit more, it looks like Ariel wasn't quite perfectly still for the shot and there's a hint of subject motion blur on her face in particular as a result. You can count petals on flowers in the foreground and trees on the far hillside. And artistically this places equal emphasis all over the frame. There's detail everywhere to invite the eye to travel around, zoom in and investigate. It's ultra-realist.
At f/16 on the 85mm shot, in theory we see the same- the whole world in focus, count the leaves. But zooming in to the full-sized version you might notice a subtle softening, a diffuse glow around highlights and a feeling that maybe the image is a bit lacking in "bite". There's also the natural effect of the 85mm focal length meaning that we're not including stuff like the telegraph wire and the distant hills in shot. As a result, even though in theory everything is quite sharp, the image actually looks a little dreamy, certainly much more so than the ultra-realist rendition of the 35mm lens at f/16. This softening effect is due to diffraction, a subtle optical effect which kicks in at some point on all lenses. This is why these particular lenses don't go to f/22 or f/32 the way some lenses do. Nonetheless, the overall impression especially on the normal-sized image is quite busy. The background has as much detail as Ariel, and the eye roams around that aimlessly.
For the head and shoulders shot, even at f/16, the background is out of focus both at 35mm and 85mm. That's because we're focussed on the subject who is much closer to the lens than she was for the full-length shot. But it is still pretty easy to tell what the background is: trees and sky and stuff. The telegraph wire crossing frame is obvious, especially on the 35mm shot.
f/16 and f/11 are what I call the "deep focus" regime. You get lots of stuff in focus, and if for artistic reasons you want sharpness front to back, this is where you need to be. For example if you have the model's tied hands coming out to camera and you want her hands and face in focus. You may still struggle, there's an interplay between where you stand, focal length, sensor size, what point in the scene you set the centre of focus to be and depth of field which is beyond the scope of this exercise (and into the regime of tilt-and-shift lenses, large format cameras with movements, and focus stacking).
f/8 to f/5.6 are what I call the "full focus" regime. Ariel is in focus head-to-toe in the full-length shots, and all of her face and hair are in focus in the head-and-shoulder shots, with detail behind just starting to fall off sufficiently that they aren't competing for attention the way they are at f/16. If you want to record the details of your bound model but are not so concerned about the detail around her, f/8 is a good place to be with a full-frame sensor and typical bondage photo focal lengths like 35mm, 50mm, 85mm. When I light with flash, f/8 is my default starting point. I'd guess half the shots I've even taken for RE were at f/8 or thereabouts. Incidentally, lenses also tend to be at their crispest and sharpest around here.
By f/4, we're losing the ability to get all of Ariel in focus at the same time, even when she's standing square-on to the camera (as I said, if you're trying to get something like a hand or foot extended towards camera and the rest of the subject receding things are inherently more tricky). F/4 on a full-frame camera at normal focal lengths is kind of a transition regime. Close enough to full focus to be able to get away with it. I don't know that you'll notice the lack of detail on Ariel's feet in the normal size shots, but in the full size versions it's starting to get obvious.
f/2.8 and below is the "shallow focus" regime. Now you're really having to choose your focal point carefully, because only a shallow slice of the scene at that distance from the camera is going to be sharply rendered. Notice in the 35mm head-and-shoulders shots that at f/16 the telegraph wire behind Ariel is not quite sharp, but very obvious. By f/2.8, it is so defocussed that you can't even tell it is there, and even in the full-length shot for 35mm f/1.4 the wire itself is really de-emphasised, although it's obvious where it meets the pole if you crop that out the wire is significantly less visually intrusive.
By f/1.4 you are having to choose your focal point with millimetric precision. At 35mm, eyes and mouth are in focus but forehead has drifted out of focus and the hair at the back of Ariel's head has gone to a soft glow. At 85mm, one eye is sharp and the other is definitely out of focus, if you look at the full-sized image! And the background has become an impressionistic blur. Stu Maschwitz calls this "the ability to shoot abstract art in Burger King".
Notice also the subtle effect on how integrated Ariel appears to be with the rest of the scene. In the full length shot at 85mm and f/2.8, she's almost floating above it. At f/1.4, it is like the background has faded away leaving our eyes with nowhere to go but Ariel's. At 35mm and f/1.4, she's the focal point but we can still see the whole world as a glamourised glow behind her (this is an expensive look, much beloved of hotel brochures). At 35mm and f/16, it's a hyper-realist painting or IMAX documentary.
Lastly, just flick between the end-point images for me: 35mm f/16 and 85mm f/1.4. These are two photos of the same model in the same place in the same lighting! One looks like it is out of Mad Max Fury Road. The other like it is out of 1970's Playboy.
That's why the choice of focal length and shooting aperture are the two most important decisions when you start making art with a camera. You need to shoot focal length and aperture series yourself and start getting a visceral appreciation of what they mean artistically for your final image.
It also explains why some lenses have become the go-to for photography. The 24-70 mm f/2.8 standard zoom straddles the wide angle through normal to telephoto focal length range. For people photography it is a bit too wide at the wide end and not really long enough at the long end (a 35-135mm lens would be better) but critically it allows access to f/2.8 aperture. This is partially for usability in low light, but mostly because it provides access to the magical shallow-depth-of-field regime which you just can't access with a f/4-f/5.6 kit zoom.
It also explains why photographers are willing to pay an extra thousand pounds and carry around an extra kilo of weight to get prime lenses which go to f/1.4 rather than sticking with the cheaper and lighter prime options at f/2.8. The 85mm f/2.8 headshot is nice, but the 85mm f/1.4 is sublime. It totally de-references the location, which is a very valuable thing to be able to do in the real world where you can't always control all the elements of your surroundings.
It's also why full-frame 35mm remains the go-to option for most photographers. Smaller formats struggle to achieve the shallow depth of field regime. Physically, because they are shooting with shorter focal length lenses and cropping in to the centre of the image - you end up with something that looks more like the 35mm f/1.4 rather than the 85mm f/1.4 shot because you are literally shooting with the 35mm f/1.4 lens, you're just not seeing the outer bits of the frame that you'd see on full-frame. Look at the two shots in this sequence: you can see that the dreamy background blur effect is much more marked for the 85mm lens than the 35mm lens. Larger formats struggle because although this effect is in their favour, it is physically hard (and expensive) to construct f/1.4 lenses that cover the whole of a medium format image, so you're stuck with f/2.8 lenses at best, and sometimes even f/4. The market isn't big enough to support massive investment in that direction, so full-frame becomes something of a self-fulfilling prophecy. Larger and smaller formats have other strengths and weaknesses for different photographic styles and subjects. But if you want the most flexibility for people photography, full-frame is it. Thats' why I've got a Sony A7RIII as well as a Hasselblad.
You don't have to shoot everything at f/1.4 by the way.It's in fashion but a bit over-used. Your viewers might well find it frustrating if they can't see details of the whole of your model's body in a bondage shot! But it's a really lovely option to have in the toolbox.