lightmeter for photography

By Ben Reeves

A long time ago, I visited Khao Kheow Open Zoo outside Bangkok and I took a picture which changed the course of my life and career. I was using a very basic point-and-shoot camera and I lined up a shot of an emu behind a chainlink fence. Once I’d had the film developed, I discovered that I’d taken a fantastic photo…of the fence. I began to realize how important it was to get the photography light settings right.

Photography Light Settings – Manual Mode

Photography light settings

My first SLR – a Pentax SP500

Shortly after that holiday, I got my first SLR camera – a Pentax SP500 – and I got my first lessons in using it. If you think that a photography course sounds like a challenging endeavour, you should try learning to load an old 35mm film SLR! This thing was almost entirely mechanically operated. It was about as fully manual as you can get, short of a pinhole camera, and yet I still sometimes miss using it.

The virtue of the SP500 was its absolute simplicity. It had less than 10 settings and functions in total. It cut photography down to its most basic principles – those of balancing the photography light settings in order to create a properly exposed image. Once you’ve figured that out, the rest of the settings on your newfangled digital cameras are just tinkering.

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Photography Light Settings – Light Meter

Photography light settings

Caption: The light meter is the scale along the bottom of your viewfinder

You may have noticed a scale along the bottom of your viewfinder while using your DSLR, with the figures -2, -1, +1 and +2 either side of a central marker. That is your light meter, and it is the most important readout on the whole camera.

That display tells you how much light is hitting the sensor. The aim is to ensure that the sensor receives neither too little exposure nor too much; so that the image is neither too dark nor too bright. This isn’t about making the picture look pretty – it’s about making the picture at all! The settings available for moving the indicator are the shutter speed, aperture and ISO.

Photography Light Settings – Aperture

Photography light settings

We covered most of this in the last post but, to reiterate, the aperture is the hole through which the light entering the lens is focussed onto the sensor. A smaller number means a larger hole (don’t ask why) and a larger hole means more light.

I also explained that the aperture has a big impact on the depth of field – that is, how much of the image is in focus. If you’re a bit hazy on the subject, go back over that post again. The important take-away from it, however, is that you can create interesting effects with the aperture settings, but that altering them will alter the amount of light entering the camera. You will need to modify other settings to maintain the right exposure level.

Photography Light Settings – Shutter Speed

Photography light settings

Note the blur on the wheels, creating the impression of movement in a still image

Blissfully, this aspect of photography does not require the reader to be a physicist. There are no complicated words, mathematical symbols or illogical conventions. Shutter speed is the speed at which the shutter moves – the shutter being the thing that covers up the sensor (or film, as it once was) until it is ready to be exposed to the light in order to form the image. It is the thing that is activated by hitting the shutter release button, which takes the picture, and it is the thing that makes the iconic clicking sound when you do.

Shutter speed is measured in fractions of a second. My old SP500 was so named because the maximum shutter speed was 1/500th of a second. My DSLR now can reach up to about 1/4,000th of a second. At the other end of the spectrum, you can slow the shutter down so that it is open for as long as 20 or 30 seconds.

The amount of time the shutter is open obviously determines the amount of light which will hit the sensor. If there isn’t much light around, you will need the sensor exposed for longer so that enough ambient light hits it and a coherent image forms. On the flip side, in bright conditions, you will need to limit the amount of light hitting the sensor because too much will overwhelm it and details will be lost in a glare of white light.

As with aperture, manipulating the shutter speed has a secondary effect. If you are taking a picture of a moving object – such as a car or motorbike – then certain parts of that object can move surprisingly far, even in as little as 0.05 seconds (1/500th). The whole time the sensor is exposed, it is absorbing details. If those details happen to move while it is open, then that movement is also absorbed.

The result of this is that you can again create some artistic effects by simply altering the balance a bit. You still have to keep the meter centred so that the image is properly exposed, but if you drop the shutter speed down and open the aperture more to compensate, you can capture movement in the form of blurring, giving your photo a more dynamic feel.

Photography Light Settings – ISO

Photography light settings

Even after using Photoshop, the grainy effect created by using a high ISO is still obvious

Back in the days of film, what is now called ISO was then called ASA, and I still haven’t the faintest clue what either acronym stands for. What I do know is the impact that altering this setting has on your pictures. Put simply, a higher ASA/ISO would mean that the film/sensor is more sensitive to light, requiring less of it to form a coherent image.

This is useful for when you are using your camera at night, as you can boost the ISO in order to compensate for the limited available light. You will still probably have to use a low shutter speed, but it means the difference between a 1/60th and a 60 second exposure. In one case, you can still just about use the camera freehand. In the other, even a tripod might not be enough to remove the blurs caused by camera shake.

As with shutter speed and aperture, altering the ISO has a knock-on effect. Increasing the sensitivity to light creates a grainy effect and, in extreme cases, digital noise – weird little green and red dots where the sensor is confused and just guesses at the right colour to use. A lot of it can be removed with special filters in Photoshop, but it is easier just to stick to the lowest ISO setting you can get away with, unless you actually want that grainy effect for the artistic value.

Photography Light Settings – Like a Pro

Photography light settings

Most professionals – particularly those who started before digital – use Manual Mode

You could, quite easily, leave most of these settings on Auto. ISO has its own auto mode and shutter speed and aperture can be set to priority modes where modifying one will automatically change the other to compensate. It makes the whole process quicker and easier.

Most professional photographers use manual mode. They do this because the microchips in even the most advanced cameras aren’t really that smart. They will prioritise making a clear picture, not a good picture. The art of photography comes from understanding these settings and the effects they create, then crafting the image you want using whatever light is available.

This is the first thing I have always taught anyone who has come to me with their first DSLR in the hope of a few pointers. In a lot of cases, it goes right over their heads, and I wouldn’t be that surprised if the same happened here. Bluntly, one blog post cannot compete with the level of education provided by a Bangkok photography course, or about six years of using something as basic as an SP500.

Ben Reeves

About The Author

Ben

He is a travel writer and photojournalist working in Phuket. Originally from the UK, he arrived in Thailand by way of Oman.