Tag Archives: Balance

The Exposure Triangle – An aid to thinking about exposure

The Exposure Triangle

• The Exposure Triangle •
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Going manual with your DSLR.

For many people exploring manual settings is a challenge. There is a lot to learn. Without guidance it is difficult to work it out for yourself. Here is my approach to the subject.

Why the exposure triangle

The “Exposure Triangle” is a memory aid to help us balance light for a good exposure.

One thing you should remember. The exposure triangle is NOT a calculator. The aim is to help you get used to using the settings. The ‘Triangle’ loses its importance once you understand the settings. Instead you will see your visualisation of the shot as more important.

Beyond auto-settings

“Auto settings” in modern cameras are average types of shot. They are pre-set in the camera programming. Sports mode freezes the action; landscape mode gives deep focus in the shot; portrait mode promotes close focus and so on. The pre-sets make credible pictures but take creative decisions away from you. Controlling exposure gives you artistic control over our photos.

It’s all about control

Photographs capture light reflected from objects in the scene. Too much light – the object is over-bright, or worse, blown out (completely white). Too little light and the light does not excite the sensor enough. Thnthe object is dark, sombre, or worse – black. At the extremes we have blown out or black. In between are a whole range of capture intensities.

The trick is to balance the incoming light so the sensor can make the picture as we wish it to come out. the idea is to control the light in-camera to create optimal light conditions for the sensor.

Three essential elements

There are three critical elements that control the incoming light…

  • ISO: controls the sensitivity of the sensor and how we capture the light brightness. A sensitive sensor allows a shot in lower light conditions (example: ISO100). High sensitivity to light is referred to as High ISO (example: very high ISO = 3000). The penalty is the picture becomes noisy (Definition: Digital Noise) as the ISO gets higher. Noise affects the quality of the picture. The lower you keep the ISO, the better quality the final image will be.
  • Aperture: controls the amount of light allowed through the lens. It also controls the depth of field. As the aperture increase the amount of light entering the lens also increases. However, as the aperture gets bigger the lens loses the ability to focus at infinity. As the focus shortens part of the picture is not so clearly defined. Taking a photo at F4 means you might be able to focus on a face beautifully and with sufficient light. But you may not be able to discern any detail behind the head. The depth of field has been shortened by the wide aperture.
  • Shutter value or Time value: How long the sensor is exposed to light affects the amount of light you collect. Leave the shutter open too long and the shot is too bright, blowing out parts of the picture. Close the shutter too quickly – the result is underexposed. Long exposures tend to exaggerate movement introducing blur. Fast shutter speeds tend to freeze an object in place.
What is exposure?

There is no right or wrong for achieving the outcome we desire. But there is only ONE point at which the exposure (all three elements combined) is right for your picture. That is the one to make your photo come out the way you want. You must find the correct exposure balance for your visualisation of the picture using all three elements.

Exposure is the right balance of ISO, Aperture and Shutter speed which provides for your intended depth of field, movement blur, brightness and representation of the scene. It is a unique response to the sensor settings you think will make your shot come out right.

The Exposure Triangle is a concept to help you adjust the balance to get the exposure right. The key to using the exposure triangle is that the three elements of exposure: ISO, aperture and shutter speed, must always balance.

It teaches us to understand how the three exposure elements play off one-another. Shorten one arrow the others will need to accommodate by adjusting their length. You can increase one or both of the other elements to accommodate the change.

If you increase one element you will need to decrease one or both of the other elements to accommodate the change.

Full Manual Control

Our exposure settings aim to balance the three elements in the camera. This needs to be done on the ‘Manual’ setting or ‘M’ setting to get the desired result. To gain full creative control we must do two things…

  • First we must have a clear idea of what we are going to achieve for each shot. Do we want the water blurred in our stream or not? Do we want the final picture to look bright and breezy or dark and sombre? Do we want movement blur or sharp, frozen action… and so on. So look at the scene and determine what you want.
  • Secondly, on the basis of what we want we must adjust the camera settings to achieve the desired result.

How do we adjust the settings to get the optimal exposure? Simple. The camera light-meter indicates when exposure is optimal.

The DSLR light sensor is the key

Inside every DSLR is a digital sensor. It detects light intensity. If the light is correctly optimised it will be indicated on the exposure meter.

With the camera set to “M” look through the eye-viewer. At the bottom of the screen you will see a scale. There should be a needle above the scale. This is the indicator of the current exposure. The centre of the scale is the correct exposure level for most shots.

If the needle is off to the right the sensor is getting too much light. If it is off to the left there is insufficient light. The trick is to balance ISO, aperture and shutter speed so the needle is centred.

Your camera manual will show you how to change each of the three settings. There are normally three controls somewhere on the DSLR body to change each of them. Again, your camera manual should have a diagram of the readings in your viewer screen when you look through it. Check out that diagram. You will see the location of the settings on the screen that will change when you alter the controls.

A trick to get you started…

Put the camera on full automatic (the ‘green square’ setting). Take a shot like the one you want. Now look at the settings for that picture on your camera screen. Your camera manual will show you which setting you can look at on the screen. This gives you a guide to what your manual settings should be for this shot.

Now switch to ‘M’ or manual to vary the results. If you want movement blur then slow down the shutter speed (longer exposure, more light let in) and/or decrease the aperture (reduce incoming light) to keep the needle in place. One click of longer shutter speed needs one ‘f-stop’ less of aperture to keep the exposure optimal. But now you get the movement blur!

The aim here is to balance a change in one element by changing one or both of the other elements. In the process you try to keep the needle over the centre of the scale in your viewer. The centred needle tells you you have an optimal exposure that your sensor can use.

Experience…

If you practice regularly with your camera on ‘M’ you will get control of your shots. Try to relate the settings to the type of results you get. Relate shutter speed to the resulting blur/sharpness. Similarly, relate depth of field to aperture size. Relate ISO to balancing light sensitivity to achieve the correct sensitivity for your intended exposure. Gaining experience with these attributes will help you remember settings to use in particular situations.

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Netkonnexion

Damon Guy (Netkonnexion)

Damon is managing editor of Photokonnexion.com with professional experience in photography, writing, image libraries, and computing. He is also an experienced, webmaster and a trained teacher. Damon runs regular training for digital photographers who are just starting out.
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The easy way to give depth to landscapes

'Reflections on a lake' - Landscapes need to have depth to be effective. Layering them is the key.

• ‘Reflections on a lake’ •
Landscapes need to have depth to be effective. Layering them is the key.
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“‘Reflections on a lake'” By Netkonnexion on Flickr External link - opens new tab/page

Everybody loves an autumnal landscape.

Come autumn we are all making great images of the colours and the changes. To be successful a landscape has to look like it has some depth. In this post we are going to look at the simple way to impart depth to a landscape.

Layers

The easiest way to create depth with a landscape is to trick the eye. You are not trying to defraud your viewer. You are simply convincing the eye there is more than two dimensions. This is easy to do because your eyes expect to see depth. What you need to do is to enable the eye to actually pick up significant markers that would lead them naturally into a landscape.

There are lots of markers that you can use in composition. In fact in Easy introduction to ‘visual elements’ in photographs we identified lots of compositional markers called visual elements. When you compose a landscape using layers you are working with lines that create the markers for depth. The lines themselves are visual elements in the picture. They create boundaries for the layers in the picture.

The example picture above is chosen for its simplicity. In the immediate foreground there is a patch of rock strewn grass. Not of great interest in itself, but it provides two elements. The larger boulder provides a bit of interest drawing the eye into the picture. It also seeks to divide the picture providing a visual balance either side. I will come back to this later.

The grass-lake boundary is the first line we cross. It is a major visual element in the scene. Its existence creates the foreground layer out of the grass and marks the mid-ground layer as the lake.

The lake itself is the central interest. In this picture it’s also the mid-ground layer. Great reflections always draw the eye. Then, on the far side of the lake is the next significant element/marker – the far lake shore line. This is the demarcation for the background layer – the trees. It is where the reflections originate.

The three landscape layers, foreground, mid-ground and background create depth. As the eye, in 100ths of seconds, penetrates the picture your eye/brain system sees the lines marking the boundaries of these clear zones. Immediately, the visual elements become markers for the eye to measure its travel into the picture. Depth has been established. You now see into an image, rather than at a picture. Visually creating layers in your composition, like these, will impart depth to your landscape shots.

More after this…

What’s next?

Once the eye/brain system has seen depth it remains in the minds eye. Of course if you want to sustain the viewers interest you have to find other things of interest. In this picture there are other ways the eye works through the image. The colours and tonal range are important, especially in autumn. The eye loves reds and russets. So that helps, as does the eye working to sustain an interpretation of the reflections. The ‘principle‘ there is the visual harmony between the reflections and the background layer.

Two other compositional elements control the eye. Normally a central feature of a picture, like the boulder, would draw the eye and hold it there if it was substantial enough. In this case our boulder is of small visual weight. It is not a major compositional feature, but more of a visual element (a ‘form’). You will recall from Simple ‘Principles’ of photographic composition that the ‘Principles’ control the way the eye uses the visual elements. Here the eye flows into the picture by being drawn through the middle, having established depth the eye does not go out the other side of the picture. The trees hold the eye in the picture – they form a barrier. Naturally, the eye is now drawn to cycle around the reflections. Eventually the eye will pick up the next clue.

This spot was chosen for aesthetics as well as the point of view for the shot because a central entry for the eye established the emphasis of both depth and a major point of focus on the middle ground. If you look carefully the lines that create the lake sides are narrower at the left side than the right. This funnel-effect will eventually channel the eye out of the picture on the right. The eye has a natural tendency to follow trending diagonals – no matter how slight – toward the wider ‘escape’ end. Yet, the boulder maintains a balance in overall visual terms between left and right. Eye movement is therefore under a tension to stay central as well as wishing to follow the flow to the right. This tension keeps the eye focused around the centre of the lake.

Fickle!

Yes, it is not a surprise that composition is a fickle thing. This is how I see my picture. In reality we all see it different ways. I have shown you how I rationalised the shot when it was taken. It may not work that way for you. If you have a different view why not discuss it in the comments. I would love to hear your interpretation.

By Damon Guy (author and Photokonnexion editor)

Damon Guy - Netkonnexion

Damon Guy (Netkonnexion)

Damon is a writer-photog and editor of this site. He has run some major websites, a computing department and a digital image library. He started out as a trained teacher and now runs training for digital photogs.
See also: Editors ‘Bio’.
By Damon Guy see his profile on Google+.