Getting the Exposure Right

Let’s talk a little about getting the exposure right, as it will start to become increasingly important as we bring more and more light into play. Now, it’s true that you can use your camera on some form of automatic exposure mode, and something like a flashgun (assuming it’s talking to the camera) in a mode like TTL and you’ll get pictures that are decently exposed. You may even be lucky, and your camera’s meter will do an OK job of mixing the light from a flash and a continuous source, but your camera’s meter will fall flat on it’s face when you start to introduce lots of different light sources, and lights that are some distance from and not connected to, the camera.

Now, I appreciate that if you’ve got a decent budget, you can go and get a whole set of flashes from the same family, like Nikons with their CLS system, or my battery powered Profotos, all of which will then allow you to use TTL metering over a distance. However, not only is this expensive – we’re talking thousands of pounds – but you’ll run into trouble if you start to introduce lights that aren’t part of this system. Your camera probably won’t be able to handle a mixture of TTL flash, manual flash, and possibly continuous light too – your exposures will end up all over the place.

Whilst you’re learning how to light, I’d stick to manual exposure on the camera, and manual power on any lights you use. Not only is this the best way to really learn what effect making changes to lights and your camera has, but it gives you repeatable consistency from shot to shot. It’s for this reason that I shoot, and light, in manual mode around 95% of the time or more – I really appreciate that consistency!

The catch is, my built-in camera meter can’t give me an exposure reading from some manually powered flash 20ft away. The great advantage of manual power and exposure – the fact that you choose what exposure you want, and the power of the light stays the same from shot to shot – is also it’s biggest drawback. It can be very easy to get the exposure very wrong when you’re in manual mode on the camera, and your flash is not talking to the camera in any way. The pulse of light from a flash is too brief for a camera to determine an exposure, unless they’re talking to each other in some way.

So how do you get a decent exposure when shooting and lighting in manual? Well, one way, and one that I actually use all the time, is simply to view the back of the camera and review the shot I’ve taken. Part of the reason I use this so often is not only is it quick and convenient, but I’m very familiar with what my lights can do, and I use them very often. I’m unlikely to set them up in such a way that I’m many stops out when I first start shooting, it’s usually enough for me to take an initial shot, and then tweak a bit here and there. I’ve been shooting for a very long time though, and I shoot hundreds of times a year too, so experience definitely helps in this regard.

Getting the Exposure Right

Be sure to set the view to include a histogram of some sort, that way you can be sure you’re actually looking at a realistic representation of the exposure, rather than being fooled by how dark or light your LCD screen is. If you’re unfamiliar with what a histogram is in relation to your exposure, I strongly suggest going and taking my technical fundamentals course, you’ll feel so much wiser afterwards. The back of the camera can also be useful for working out if extra lights you’re adding to a shot are having the effect you want. 

The most accurate way to determine exposure, particularly if using more than one light source, is to use a handheld meter like this one. They’re not too expensive, and they last forever – this is about 20 years old. All they do is measure the light, and they can be used to measure flash as well as continuous light, and even trigger flashes too.

One important thing to consider is that a handheld meter like this measures what is called the incident light. The meter in your camera will be measuring what’s called the reflected light – the light that bounces back from the subject – and this of course can be affected by how bright or dark your subject is. Stand 2 different people in the same amount of light, and a reflected meter will give you a different reading for the one wearing all black, and for the one wearing all white. An incident meter measures the light that’s falling on your subject, so it’s not affected by overly dark or light subjects.

To use, you simply set your ISO, as well as your aperture or shutter speed, depending on what mode you’re using, then press the big button to take a reading. Then you set your camera to what the meter tells you. Here’s the tricky bit though – these meters are very accurate – they can give you a reading to within one tenth of a stop – and don’t forget that it’s reading the light falling on it. This makes where you place it to take the reading really important.

If you dig around online, you’ll hear several different suggestions as to where you should place the meter to get the most useful reading. I was taught many years ago, that firstly, make sure to place the meter in exactly the light that I was trying to get a reading from, rather than a brighter or more shaded area. Then I was told that it’s a good idea to actually face back towards the camera – although this generally applies most when you’re shooting portraits. Since meters are so accurate, the angle you hold it at can make quite a difference – I’m being lit by a light bounced off the ceiling here, and if I turn the meter from facing up, to straight on, to facing down, I’ll get a range of almost a stop and a half, so something as subtle as the angle of your wrist can make a difference.

To check the exposure of other lights in the scene, simply point your meter back to them, and take a reading. It may help to shade the light from other sources with your hand to exclude their input and avoid confusing the reading. Using this method you can be very precise about how powerful your other lights are in relation to your key. Let’s say you’re shooting a simple headshot like this, you meter the front light to be f8, and you want the back light to be a stop brighter, so you simply aim the meter at it, making sure to mask the light from the key, and adjust the power until your meter reads f11.

So, we know we’ve got to be careful exactly where we place a light meter, but the last thing we need to bear in mind is that there may be a difference between what the meter says, and how your camera is set up. If you remember the basics of exposure, you’ll recall that f8 on one lens is the same as f8 on another lens, and ISO 100 is the same from camera to camera, and so on. I’m afraid to report that in practice, this isn’t 100% true. Different lenses and camera sensors can actually vary quite a lot. Lenses are simply not made to as consistent standards as you’d imagine, and camera manufacturers often try and claim that their sensors are more sensitive than they actually are. In order to get the best from your light meter, you’ll need to calibrate it to your lenses and your camera – essentially, work out what the difference is between what the meter is telling you, and what your camera or lens are actually set to. Back in the olden days of film, it was very common for film manufacturers to make slightly generous claims for the speed of the films they sold – in my experience, most films needed about 1/3 more exposure than they claimed – if they were sold as ISO 100 for example, I’d usually set the meter to ISO 80 – so this is nothing new.

The best way to calibrate your meter and camera is to shoot a test subject – something that will stay consistent from shot to shot, and ideally lit with fairly soft light to reduce the risk of you placing the meter in a particularly bright or dark area. Take a reading with the meter, and transfer these settings to the camera, then take a shot. Do this with different lenses – so ensure you get an exposure with an aperture that all your lenses have – and see if you notice any difference. I’ll be willing to bet that you will see some shift from lens to lens, although hopefully it will only be minimal. Once you know how much this shift is make a note of it somewhere memorable – on your smartphone, or in your camera bag – and then in future, you’ll know that, say, your 85mm needs 1/2 a stop more than the lightmeter says. In the case of your camera’s sensor being off – and they usually claim to be more sensitive than they actually are – simply set your light meter to the right speed whenever you use that camera. So, if you think your camera is always underexposing everything by 1/3 of a stop each time you use your handheld meter, simply set your meter to 1/3 of a stop slower, and away you go.

Whichever way you use a lightmeter, consistency is key. If you get in the habit of always taking readings with the meter angled a certain way, stick with it – if you start metering in all sorts of different ways you’ll cause no end of confusion. I still use a meter like this from time to time, as it gives me more accuracy than just eyeballing the shot on the back of the camera, and if I’ve got a very complicated setup, it can be essential. Not a bad investment to make, but only worth it if you use it properly!

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