When we last discussed photography techniques we concentrated solely on shutter speed. Today, we’re going to continue our discussion with the other two primary factors that affect exposure: aperture and ISO. Aperture tends to be the one that frightens people most, what with talk of f/numbers and all that. As I’ve written previously, there’s no need to get caught up in the numbers or worry about what they mean – you just need to be aware of how they affect things. ISO is the final piece in the exposure triangle. Remember, changing either your shutter speed, aperture or ISO has an automatic knock-on effect on the other two factors.
For this post we’re going to concentrate on setting your Canon camera to Av (Nikon/Sony to A) and we can work from there. In this mode, you decide the aperture value and your camera figures out what it believes to be the correct shutter speed value (I say believes, because it sometimes gets it wrong as it can be tricked by particularly bright or dark areas within your frame).
Latin for ‘opening’, the aperture mechanism is housed inside the lens. In most cases it is simply an electronically controlled iris that can be opened wide or closed down to control the amount of light passing through the lens into the camera. When wide open (which equates to a low f/number i.e. f/2.8) the lens is allowing the maximum amount of light it is capable of to pass through as pictured above. An effect of a wide aperture is a much narrower depth of field (less objects in focus). In contrast when the aperture is closed down to its smallest opening (which equates to a high f/number i.e. f/16), the lens is allowing the least amount of light to pass through. This results in a wider deeper depth of field (more objects in focus).
You can check out what your maximum aperture opening is by looking at the markings on your lens. A Canon 24-105 1:4 L IS has a maximum opening of f/4 throughout its entire focal range. A Sigma 17-70 F2.8-4 is capable of f/2.8 at 17mm but due to the design of the lens, can only open to f/4 at 70mm. Lenses that have fixed aperture values, that is, a lens capable of the same maximum aperture value throughout the entire focal length tend to be either expensive, or a prime lens, or both.
You will find that a lot of the Speedhunters team favour fast prime lenses as they tend to offer superior sharpness, quality and a much wider aperture opening than their zoom brethren. That being said, there is always room for a good zoom lens in your arsenal, especially when versatility is required.
Canon EOS 5D MKII with Canon 85mm f/1.2 L, 1/6400th, f/1.4, ISO100
With the details out of the way, let’s take a look at aperture from a more practical perspective. When do you choose to use aperture priority?
Canon EOS 1D MKIII with Canon 70-200mm f/2.8 L IS, 1/400th, f/2.8, ISO200
Whenever you want really. I tend to use aperture priority when I’m not looking to display movement in a shot and/or when I’m more concerned about the depth of field.
Canon EOS 7D with Canon 300mm f/2.8 L IS + 1.4XTC, 1/500th, f/4, ISO400
Another instance where I will choose aperture priority is when I want the fastest shutter speed available. By shooting wide open (or close to it), you’re allowing all of the available light to pass through the lens into your camera. To prevent the shot from being overexposed, the camera will use the fastest shutter speed it can manage which results in the shutter being open open for the shortest amount of time resulting in frozen action.
Canon EOS 1D MKIII with Canon 300mm f/2.8 L IS + 1.4xTC, 1/2000th, f/4, ISO400
It’s worth pointing out that if you choose to use a teleconverter to increase your effective focal length, it’s going to reduce your maximum aperture value. As above, an f/2.8 lens will be reduced to f/4 with a 1.4xTC. If it was a 2xTC, f/2.8 would become f/5.6.
Canon EOS 7D with Canon 300mm f/2.8 L IS, 1/400th, f/2.8, ISO250
As we know, a common result of shooting wide open is a fast shutter speed. Sometimes this is desirable – other times it’s not. Let’s face it, if a car looks like it’s parked on the track in your photograph, it’s probably not going to set the viewer’s world alight. But what if you want that silky smooth shallow depth of field and you want to show some movement too? This is where your third factor can help you out some, your ISO. By decreasing your ISO, and in-turn reducing your camera’s sensitivity to light, you can shoot wider apertures with slower shutter speeds.
For the above I’m at ISO250 and the camera responded with a 1/400th at f/2.8. Let’s just say I was at ISO500, I would have ended up with a shutter speed closer to 1/800th at the same aperture which would have pretty much killed any sense of motion in the spinning wheels. Similarly, if I wanted to show more motion, I could have reduced my aperture further but I would then risk losing the shot to camera shake or just to the movement of the car.
Canon EOS 5D MKIII with Canon 35mm f/1.4 L, 1/800th, f/2, ISO100
So, what are the downsides to shooting wide open? Dependant on lens, you’re usually shooting through your lens at its worst. Wide open images tend to be a little bit softer than their stopped-down relations (stopping your lens down is reducing the size of the opening or increasing the f/number). Also, shooting wide open can enhance defects in the lens such as chromatic aberrations, which manifest themselves as green or purple colour fringing in certain areas of the photograph.
I try to shoot a little bit stopped down with my faster primes (at f/2 in this case instead of its maximum aperture value of f/1.4) as it results in superior image quality.
Canon EOS 5D MKII with Canon 85mm f/1.2 L, 1/800th, f/1.2, ISO50
As we publish most of our work online at a resolution of 800PX wide, we tend to be able to get away with a little bit of softness or chromatic aberration here and there, as you tend not to notice it as much as you would the same photograph spread across two pages of your favourite car magazine.
Canon EOS 5D MKIII with Canon 24-105mm f/4 L IS, 1/160th, f/8, ISO100
Of course, when you need absolute sharpness and detail from front to back, you need to stop your lens down significantly. For this particular promo shot, f/8 was enough to ensure maximum sharpness throughout the image. At full resolution, you wouldn’t believe the amount of defects the camera and lens picked up. From cigarette butts on the ground (which have since been photoshopped out) to the light swirl marks in the GT86′s paint on the left of the image.
Canon EOS 5D MKIII with Canon 35mm f/1.4 L, 1/160th, f/8, ISO100
Traditionally, a large depth of field (high f/number remember) is required when shooting landscapes too. Of course, you can always experiment and compare the different results afterwards.
Canon EOS 1D MKIII with Canon 70-200 f/2.8 L IS, 1/250th, f/2.8, ISO3200
We can’t finish this part of the guide without talking about the often over-looked ISO. As you should know by now, ISO is simply a rating on how sensitive your camera is to light. A low ISO number and your camera is pretty resistant to light, a high number means the opposite.There are drawbacks however for using a higher ISO, as the resulting images will contain significantly higher noise levels (which manifests itself as small coloured dots across the image), will be slightly softer and the colours will be a little muted also. You should always try and use the lowest possible ISO for any given situation.
Canon EOS 5D MKII with Canon 35mm f/1.4 L, 1/40th, f/1.4, ISO3200
Unfortunately, some situations dictate a high ISO and the resulting grain. It’s also one of those times where you will be required to think for yourself, as the cameras internal systems struggle to identify what the correct exposure is. For the above, you should note that I’m shooting wide open (to allow the most amount of available light in), I have the ISO wound up pretty high so as to increase the camera’s sensitivity to light and and I’m shooting a relatively slow shutter speed to increase the amount of time that the light can be absorbed into the camera. Essentially, I’m doing everything in my power to grab an exposure. Instances like this will show up every weakness in your camera and lens setup.
Canon EOS 1D MKIII with Canon 70-200 f/2.8 L IS, 1/80th, f/2.8, ISO3200
You often have to think outside the box in situations like this. I try to avoid using on-camera flash as much as possible (because I don’t like the result, especially in low light conditions) so I try to use the headlights of the car behind, to illuminate the car in front. Of course, this is a game of chance as you can’t depend on every car to have a car behind it, and you really have to play the waiting game. But I’ve had success with this strategy.
Canon EOS 5D MKII with Canon 24-105mm f/4 L IS, 1/40th, f/4, ISO5000
It’s also worth trying to sync your shot with another photographer who is shooting with on-camera flash. It’s rather difficult, and you will need to spray and pray a little, but the results can be quite dramatic.
If you have any questions, or if you want me to elaborate on any points made above or before, please leave a comment below. Safe shooting!
would there be any chance to a glossary of some sort with all the technical camera jargon?
great post by the way!! Looking forward to the post processing one...!
To understand the effect of different aperture settings I recommend the following easy exercise: Choose a non-moving subject and shoot it from the same angle from f2 all the way through to f16 (depending of your lens of course!). This allows you to see the effects on the DOF as well as determining at which aperture your lens gives you maximum sharpness.
Personally I tend to shoot in aperture priority mode at car events with exhibit areas (essentially consisting only of parked cars) and switch to full manual mode when there's movement involved. I'm still practicing the latter part as I find it quite challenging to get a movement shot to look great, especially when shooting fast race cars. Thankfully I'll get to practice a lot at the upcoming WRC round here in Germany :-)
Is it possible to do a story covering different shooting situations? Like, shooting a car against a setting sun properly, or shooting straight into the headlights of a car etc.
Shooting in the cover of darkness shows all the flaws and limitations of a camera. If it is night time shooting, Make sure you bring a tripod with you. The built-in flash is useless, buy a dedicated one. Unless you're aiming for a grainy finish (film texture), don't go too high on ISO unless it is the last resort. Aperture can work wonders, like what Paddy said. As time goes on, your images will suffer from dead pixels. It can easily be fixed by Photoshop, unless it is one big blot.
Paddy, are there ever times professionally when it's appropriate to over-expose a shot? Ps, you are the wizard of B&W
Good advice :)
You should try using Tv or S mode for movement, and use your exposure compensation appropriately. A lot easier than shooting full manual.
Yes, this is planned for later in the year. We want to make sure the basics are covered in detail first.
@Edohaus I'd argue the exact opposite, if anything shooting in the cover of darkness shows the strengths of modern cameras. We're able to do things now with high ISO on modern DSLRs that no film could ever dream of replicating. You think ISO 12600 is noisy, try shooting with ISO 1600 color negative... You'd be SHOCKED at how good the digital version is, while being many times more sensitive. I find most modern cameras are exceptional up to ISO 4000 which, again, is three stops better than 1600 speed film and many many times better resolution with far better signal-to-noise.
@Edohaus I wouldn't recommend a tripod trackside unless you're trying to capture light trails or non-moving objects. To be fair most modern DSLRs handle high ISOs fantastically with regards to noise, and noise reduction software is at a level we could have only dreamt of before. The obscure point I'm trying to make is do everything to get your shot, and worry about noise and grain later.
@alanl18 I was thinking that I might get all the team to contribute to a piece where we talk about our favourite setups later in the year. It won't be reviews as such, but might be interesting all the same?
@AmericaMan In saying that, some of the glass I use is so damn sharp wide open, the 85mm f/1.2 in particular.
@JSequoia Depends on the scenario and camera system, but a general rule of thumb is to overexpose or "expose right" on a Canon and underexpose with a Nikon. Due to the RAW languages of each camera they process differently but I find Canon files pull back much better than the push up and Nikon is exactly the opposite.
@JSequoia Absolutely, you should never be afraid to over / under expose shot if it's giving you the result you seek. I tend to overexpose when shooting into the sun as the camera is usually overwhelmed by the bright source of light and underexposes the image as a consequence.
@PaddyMcGrath @Edohaus Related to tripod usage, I was wondering if there's a shutter speed you would not go hand held with. I've always heard not to go under 1/60 but I noticed that some of these were at 1/40. Were those hand held and you were just steady enough to get a clear shoot with some luck, or were those tripod shots? Thank you.
@PaddyMcGrath Yes yes. If it is on track, a tripod isn't ideal as you tend to move around. I totally agree with you about getting your shot no matter what. I learned this the hard way before, shooting one shot at a time. Now, I try to set my shots in bursts to capture the moment.
dude, this is so true! i've been running an intro level Nikon for several years now, but by shooting RAW, using prime lenses, and always always working to use the lowest ISO possible i've been able to get some great stuff....at least untill the sun goes down (anything past ISO 800 gets too grainy for my little setup). Anyway, I'd say your spot on about the different systems. But when i see shots like the one of Camille in the recent #gatebil announcement i'm wondering if the Canon sensors are able to see over a greater number of "stops" or wider range of highlights and shadows? So much of that shot is flared, soft, and overexposed, yet the subject is crisp! Cheers guys, you rock!
@trampaonline You're welcome! Experiment what works best for you since there's no size fits all.
@Edohaus Thanks, I'll have to try that method.
@Louros Thanks! Seems easy to remember too.
@Louros @trampaonline @PaddyMcGrath What I usually do is the sniper's breathing method - exhale all the air out and shoot. Another one is using a post or a sturdy wall to anchor my body. Like what @PaddyMcGrath said, get the most of what you can since time is of the essence. @Louros was right, but you can go lower than that using the techniques I've mentioned. But you can only go so far, so the only way is to boost your ISO and make the aperture wide open.