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Take Control Of Your Camera

Take Control Of Your Camera

“One of the many revelations that photographers have is discovering the difference between letting your camera decide how to do something, and telling your camera what to do.”  James Brandon

The camera doesn’t see what we see, and we need to be both highly aware of that and know how to compensate for it. The human eye sees a scene or object just as the camera sees it, but this is not the picture created in our mind. Our brain only uses the information received from our eyes and then intelligently interprets the information to create a mental image with detail that has effectively been prioritised based on interest. What we really see is our brain’s reconstruction of a scene based on the input provided by our eyes, and not the actual images received from our eyes. This is why two people can look at the same scene, but see two different pictures. Their eyes send the same information to their brain, but based on interest they see different pictures. This has an important but often overlooked implication for photographers, because you have the ability to create the interest in a scene you want your viewers to see. And you don’t need an expensive camera to do it; you just need to be smart with your camera settings.

Your camera’s automatic mode is not your friend. In full automatic mode your camera is designed to capture the entire scene in front of the lens as accurately as possible. Usually you see something of interest in a scene, a specific object or attractive lighting, and you also want your viewer’s attention on the very same object when viewing the photograph. After all, this is the reason you took the photo in the first place. If you don’t tell your camera on which object you want your viewer’s attention, your camera will capture the entire scene as if everything is of equal importance. This non-selective vision of a camera is a significant difference from the human selective vision. For example, often we see a photo where it looks like a little branch of a tree is growing out of someone’s ear, but with our naked eye there was no way we could imagine it, because our attention of interest was on the person and not on the tree in the background. Yes, our human three dimensional view also play a role, but with just a few simple camera settings you can draw all the attention on the person and create an interest with your viewers on the person and not on the tree in the background. Or we take a picture of someone in front of a bright background and end up with a photo where the person’s face is almost dark; however, with our naked eye the lighting was just perfect on the person. To set the cameras exposure on the person, rather than the entire scene is exactly what our brain did with the images received from our eyes. Our brain also corrects the images received from our eyes for all sorts of optical deficiencies from experience how the image is supposed to look like, e.g. we know a branch can’t grow out of someones ear. Cameras are not so clever, so we need to be smart with our camera settings if we want our viewers to see the picture as we did.

Your camera can’t know what part of the scene or object/person in the scene you want to emphasise, and for another photographer it might be a different person. Maybe you want to show motion in the picture, or just freeze a fast moving object, and it is not fair to expect your camera to read your mind and know what you want to achieve. If you fail to tell your camera what you want to achieve, your camera will guess, and you will probably end up disappointed with your camera’s guessing. The two of you can work together and not against each other.

“The difference in “seeing” between the eye and the lens should make it obvious that a photographer who merely points his camera at an appealing subject and expects to get an appealing picture in return, may be headed for a disappointment.”  Andreas Feininger

But how can I tell my camera to show the world as I see the world? Hang on; it is not as difficult as it sounds. This article will be much easier to understand if you first read the previous blog post “Understanding your Camera“. This article is about what effect the different parts of the camera (as described in the previous blog post) have on your image, and how to control each part.

EXPOSURE TRIANGLE

control-camera-exposure-triangleExposure is the amount of light a camera captures when a photo is taken and will result in how dark or light a photograph will appear. Too much light results in a washed out photo (overexposed), and too little light and the photo will be too dark (underexposed). Exposure is determined by only three camera settings: Aperture size, Shutter speed and ISO speed. These three settings are also referred to as the “exposure triangle”. Between the three of them, they control the camera to make a properly exposed photograph, and each setting controls exposure differently:

  • Aperture controls the amount of light that enter your camera.
  • Shutter speed controls the duration of exposure.
  • ISO speed controls the light sensitivity of your camera’s image sensor.

One can therefore use many combinations of the above three settings to achieve the same exposure, and they also allow you to control how each photo will look. Once you understand what affect each of these controls has on the image, you will be able to use them to creatively capture those wonderful photos that you envisioned. You will be able to direct viewers’ attention right where you want it.

  • Aperture controls the Depth of Field (DOF).
  • Shutter speed controls Motion.
  • ISO speed controls Image Noise.

DEPTH OF FIELD

control-camera-locksDepth of field, also called focus range, is a powerful tool to direct viewers’ attention to where you want it, and can change the meaning and intention of an image.

A camera can only focus at a single point, but there will be an area that stretches in front of and behind this focus point that still appears in focus, and that area is called the depth of field. The areas beyond the depth of field appear blurry. You can choose to selectively emphasise a subject by blurring the background, or you can make everything from the foreground to infinity in focus.control-camera-dwarfs

The left photo of the dwarf statues has a wide depth of field, while the right one have a shallow depth of field to draw the attention to the dwarf in the middle.

control-camera-lion-cubThe photo of the lions was taken with a large aperture to blur the lioness to intentionally draw the viewer’s attention on the cub.

The depth of field is mainly controlled by the aperture of your lens and the focusing distance between the subject and your camera. The aperture is a very creative control and refers to the adjustable opening in the camera lens. The aperture setting controls the size of the lens opening that allows light into your camera. The larger the aperture, the more light you let in with each exposer, and the smaller the aperture, the less light you let in. A larger aperture means less of the photograph will be in focus (shallow depth of field), and a smaller aperture means more of the photograph will appear to be in focus (wide depth of field).control-camera-aperture

control-camera-lensLenses are usually calibrated to give you a good indication of the range of distances that will be in focus. The distance between the corresponding f-number lines on the bottom of the lens will be the area in focus (see image of lens).

Focusing distance also plays a part in the depth of field. The depth of field when focused on a subject far away will be much more than when focused on a subject that’s close to the lens. The size of the image sensor also plays a role in depth of field. The larger the sensor, the shallower the depth of field will be at a given aperture, because you’ll need to use a longer focal length lens due to the image sensor crop factor.

The viewfinder or life view screen of your camera is always displayed at the lens widest aperture; however, many digital cameras have a depth of field preview button to allow you to view the scene at the selected aperture.

MOTION BLUR

control-camera-balancedAnother technique to direct viewer’s attention to a specific subject in your scene is by using motion blur. Motion blur can eliminate distractions, or can be used to emphasise a stationary subject amongst movement, e.g. a person standing still amongst a bustling crowd.

control-camera-corkShutter speed is one of the most powerful creative tools in photography. The shutter is the only thing between the light that has passed through the lens and the image sensor or film. The shutter speed controls how long the shutter opens to expose the image sensor to the light in the scene. A fast shutter speed can freeze a fast moving subject, and with a slower shutter speed the sensor is exposed long enough to the subject to allow us to ‘see’ the movement of the subject. Shutter speed is the setting that has the widest range of possibilities.

control-camera-windflowerThe photos of the windflower show the effect in different shutter speeds. The windflower rotates at the same speed in all three photos, but the left photo was taken with a faster shutter speed, while the right photo with a slower shutter speed.

 CAPTURING MOTION TECHNIQUES

control-camera-trainWith motion blur you can either blur the background or your subject to emphasise movement. The amount of movement you capture will make your subject an unrecognized streak, or as a more defined blur. All these choices are possible just by controlling your camera’s shutter speed.

To get a feeling of movement in your images you can either have your subject move or have your camera move. To capture motion you should have at least one part of the image sharp without motion blur, unless you are going for a purely abstract image.

There are basically three techniques to capture motion. Moving the subject with the background sharp, moving the background with the subject sharp, and zooming blur.

MOVING THE SUBJECT WITH THE BACKGROUND SHARP

control-camera-swingsA technique to communicate that your subject is moving is to blur your subject while freezing the background. To accomplish this, you would use a slow shutter speed, depending on how fast your subject is moving and how much motion blur you want to have on your subject. It is important to have your camera mounted on a tripod to avoid any motion blur on the background. The tripod keeps the camera still while the subject moves trough the frame, blurring only the subject while keeping the background crisp and clean.

MOVING THE BACKGROUND WITH THE SUBJECT SHARP (PANNING)

control-camera-cheetahA second technique to communicate movement or to focus the attention on your subject is to blur the background and freeze your subject. With this technique you’ll be panning your camera along the directional path of your subject. The shutter speed should be just slow enough to cause the background to streak, but fast enough that the subject still appears sharp. Panning requires that you follow your subject with your camera while taking the photo. It is important to match your subject’s rate of movement to ensure that your subject will appear still in the photo while everything else is blurred in the direction of your subject’s motion. This can be tricky and you will probably need to take many photos to get it right.

ZOOMING BLUR

control-camera-crowdZooming blur, or often called “zoom burst” is another interesting technique and require changing the zoom of the lens during exposure. This cause the scene to have radial blur near the edges while the centre appearing sharp. This technique can be used to draw the attention to the central subject in the scene. The photo of the crowd is a good example to draw the attention to the little boy who could otherwise have easily gone unnoticed in the crowd.

To capture good motion blur images is an art, so don’t be disappointed if your first few batches fail to impress you. You’ll be amazed at what you can do when you get creative with motion blur.

What shutter speed do I have to select to capture motion?

control-camera-waterfallsIt all depends on the speed of your subject and the amount of movement you want to capture. A moving snail and a running horse will give you very different results at the same shutter speed. A shutter speed of 1/400 sec. will freeze the action of someone running, and if you want to show the motion of the person running, you can use a slower shutter speed such as 1/30 sec. As the shutter stays open, the person will run through the image field. If you want to add a silky look to flowing water, you can set your shutter speed to 1 second or more. It is important to use a tripod if using such low shutter speeds to avoid blurring caused by camera movement.

 How do I know when to use a tripod?

To keep at least a part of the photo sharp, you will need a tripod when using a slow shutter speed to avoid blurring caused by camera movement, except when you’re panning your camera. The focal length of the lens you use will serve as a guide to determine below which shutterspeed a tripod is recommended. You will need to increase your shutter speed while taking handheld photos with a telephoto lens. This is to avoid blurring caused by shaky hands, because slight hand movements are also magnified. Some people have more sturdy hands, but a common rule of thumb for handheld photos is to set the shutter speed on at least as fast as one over the focal length in seconds. For example, when using a 300 mm focal length lens, the shutter speed needs to be at least 1/300 seconds for handheld photos. This rule only applies on a full frame camera or a 35mm film camera. For cameras with smaller sensors one needs to convert the focal length to a 35mm equivalent as described in the blog post “Understanding your Camera“.

 Watch out for over exposure

A common problem with long shutter speed shots is too much light which result in the risk of overexposing your image. To compensate for too much light you can use a small lens aperture and reduce the ISO speed of your camera. Sometimes, especially during daylight you will still have too much light even after your aperture is set on its minimum size and your ISO speed is also on its minimum setting. To reduce the amount of light entering your camera you can use a Neutral Density (ND) filter. These filters simply block the light entering the lens and are available in different strengths. It is almost like putting sunglasses on your camera.

ISO SPEED

control-camera-isoThe ISO speed controls the sensitivity level of the image sensor to light, its light gathering ability. If you still happen to use a film camera, then you will know that you can buy films with different ISO ratings. The higher the ISO rating, the greater the film’s ability to capture images taken in low light, which means the film is more sensitive to light than one with a lower ISO rating. However, using a higher ISO film, such as ISO 800 or ISO 1000, results in noticeable film grain. All of this applies to digital photography as well. Because the image sensor replaced the film, the sensor sensitivity can be adjusted by changing the ISO setting. Higher ISO settings are particularly useful in low light conditions without reducing the shutter speed or widening the aperture more than you want to, but it comes at a cost. Light in a given exposure is more accurately represented with a lower ISO. If you’ve seen photos at night, the lights often look like they’re much brighter and bleeding into other areas of the photo. This is the result of a high ISO, a greater sensitivity to light. Today’s cameras, especially the higher-end cameras with larger image sensors, can set the sensitivity of the sensor (ISO) to such a high number that they can almost photograph in the dark, but image noise, the appearance of digital grain is going to occur (see images of the London Bridge). Because of the graininess (image noise) of images caused by high ISO settings, as a rule use the lowest ISO possible, except if you want to achieve a specific look.

Common ISO speeds include 100, 200, 400, and can go up to 6400 or more on high-end cameras. Most of the newer DSLR cameras have a large range of ISO and handle high ISO’s really well.

COMBINING THE SETTINGS

control-camera-exposure-sheetTo set the correct exposure you need to get the right combination between the aperture, shutter speed and ISO setting. The easiest way is to decide which of these three settings is the most important for the photo you want to take, and then give priority to that setting. For example, if you’re photographing sport, you will probably make your shutter speed your priority and set the other settings to whatever is necessary to get the right exposure. For a fast moving sport like motor sport, you will need a higher shutter speed (like 1/1000 sec. or more), and for a slower moving sport like soccer, 1/250 sec. should be fine, except if you want to add motion blur. You will soon find out what the minimum shutter speed for a specific type of sport is.

For portrait photography you will probably require a shallow depth of field, and for landscape photography a large depth of field. You’re priority will then be the aperture setting.

Usually you would set your ISO setting on the minimum (on most cameras ISO 100), for the best image quality, except you want a grainy image for artistic purposes. If you photographing in lower light conditions and your photo is underexposed when you set your camera on the required shutter speed or aperture, you can increase your ISO speed. It depends on the type of camera, but on most cameras you should not notice a difference in image quality with the naked eye up to ISO 400. On higher-end cameras you can comfortably use an ISO speed of 800.

The table show aperture and shutter speed combinations which all result in the same exposure. All cameras or lenses don’t have the same range of aperture values.

Aperture Setting Relative Light Shutter Speed
f/1.4 256 X 1/125 second
f/2.0 128 X 1/60 second
f/2.8 64 X 1/30 second
f/4.0 32 X 1/15 second
f/5.6 16 X 1/8 second
f/8.0 8 X 1/4 second
f/11 4 X 1/2 second
f/16 2 X 1 second
f/22 1 X 2 seconds

In manual mode your camera should tell you how your exposure will turn out based on the Aperture, Shutter speed and ISO settings. However, keep in mind that this relies on the camera’s metering system and should only be use as a guide. For tricky subject matter, the camera metering can be fooled.

UNDERSTANDING YOUR CAMERA METERING

Knowing how your camera metering works and what each of the metering modes do will be very usefull to helps you control the exposure. Cameras today have an integrated light meter that automatically measures the reflected light from your scene and determines the exposure. Subjects vary greatly in their reflectance, therefore in-camera metering is standardised based on the luminance of light which would be reflected from an object appearing as middle gray. Different cameras treat middle grey slightly differently, but it is usually somewhere between 10% – 18% reflectance. Reflectance of more or less might cause you camera to overexpose or underexpose the photo.

Metering Modes often include:

Matrix or Evalutive metering – usually the default metering mode and set the exposure for the entire scene.

Center-weighted metering – set the exposure for the area in the middle of the scene.

Partial metering – covered area approximately 13% of the scene.

Spot metering – covered area approximately 3.5% of the scene.

By default, the camera will try to come up with an exposure that balances the bright and dark areas in the entire scene. If you photograph a person in front of a bright background for example, the centre-weighted or spot metering comes in handy. It reads the light on a specific area of your scene and ignores the rest. Use this mode if you want your camera to prioritize a specific subject in your scene. Center-weighted mode evaluates the light in the middle of the scene, while partial and spot metering evaluate the light around your focus point and ignore the rest.

SHUTTER PRIORITY & APERTURE PRIORITY MODE

Most digital cameras have a semi-automatic function or selection called “Shutter Priority” and “Aperture Priority”.

In Aperture Priority mode you specify the aperture or f-number, and the camera’s metering will determine the corresponding shutter speed and ISO speed to ensure the photo is well exposed.

Shutter Priority mode allows you to specify the shutter speed, and the camera’s metering determines the corresponding aperture and ISO speed. This can be extremely useful when photographing a sporting event because you may not have time to select the aperture for the correct exposure. However, this is not a blanket solution for every situation. For some tricky situations you may have to set your camera on full manual mode to get it right.

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