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Exposure – the ISO, Aperture and Shutter Speed Triangle

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Exposure – the ISO, Aperture and Shutter Speed Triangle Camera Modes Understanding DSLR Camera Shooting Modes A digital camera comes with a selection of Automatic camera modes. These are pre- programmed settings that allow you to choose the optimum shutter speed and aperture value for the photograph you want to take. They are useful when you are starting out. Familiarize yourself with the settings and get comfortable with them; and remember that every camera has slightly variable preset modes. The following are the most common: 1. Auto Mode Automatic Exposure is when the camera chooses the optimum shutter speed, aperture, ISO and flash settings for your shot. All you need to do is point and shoot. This can be good if you have no idea of what settings to choose and also when you need to shoot quickly. The shot here is perfectly exposed as the day is well lit, though auto-exposure may struggle in situations where the light is uneven, and it tends to trigger the flash even when it’s not necessary. 2. Portrait Mode Portrait mode will “think” that there is a subject in the foreground of the frame and choose a shallow depth of field in order to keep the human subject in focus but the background blurred. If the camera reads the scene as dark, it will add fill-in flash. Fill-in flash is useful in sunny conditions too, when the sun casts a harsh shadow. Portrait mode generally works best in well lit conditions. 3. Macro Mode Macro mode is very useful to take a photograph of an image smaller than your hand. Remember that macro mode will not give you super close up images; for this you will need a macro lens. Macro mode will work best in bright conditions and will choose a shallow depth of field to focus on the subject. Therefore, if light is low, use a tripod. Your focusing also has to be more careful when taking a macro image. This is because when you use a shallow depth of field, you give yourself a smaller margin for error. 4. Landscape Mode Landscape mode usually uses a small aperture (high f/number) to create a well focused image from the foreground into the distance (on old style cameras, the setting was ‘infinity’ represented by a sideways figure 8). Landscape mode tends to suit a wide lens, and again works well if the scene is well lit. It will use flash if it reads the foreground as too dark, but you can manually turn this off. 5. Sports Mode Because sports are fast paced activities, sports mode will give you a high shutter speed of at least 1/500 – 1/1000 of a second. With a high shutter speed to freeze movement, this works best on a bright day. Sports mode can work well alongside continuous shooting mode, where images are taken consecutively – the result is a number of shots capturing action in mid air. 6. Night Portrait Mode In the night portrait mode, the camera will try to balance the darkness of the background with the need to light the subject in the foreground. The aperture will have to be fairly wide to allow enough light in to capture the background and keep the subject in focus, but at the same time flash is necessary to illuminate the person and avoid blur. Sometimes the night portrait mode will double flash, creating an unusual double exposure look Advanced Camera Modes On most DSLR cameras, there will also be the letter modes – M (Manual): Manual allows the photographer to change every single setting AV (Aperture-Priority): Aperture-Priority allows the photographer to set the aperture value and the camera automatically sets the correct shutter speed. Uses portraits, event photography TV or S (Shutter-Priority): TV lets the photographer choose the shutter speed first (for example when shooting sports) and the camera automatically sets the correct aperture. P (Programmed Auto): P-Program mode is similar to Auto mode - the shutter and aperture settings are determined by the camera, but the photographer can adjust the shooting and image-recording functions such as ISO and exposure compensation. Metering and Exposure Why is this so important? So you can accurately represent the image by capturing all the details, colours, shadows and textures. I’m sure by now that you’ve taken an improperly exposed photograph while “experimenting” with your camera, and have seen the loss of image information in the highlights. Unfortunately with digital photography once you’ve over-exposed an image, that image information is gone forever. So ignore this at your own peril, or watch your skill flourish. Center-Weighted Metering In this mode, the camera measures the light information originating from the middle of the viewfinder (it also absorbs image data from the rest of the frame, but the computer gives that light less importance). This setting causes the camera to focus on the subject in the middle of the frame and isn’t too influenced by any excessively dark or light backgrounds or sides of the frame. This setting is ideal for when your subject is in the centre of the frame, for instance, a portrait, your sleeping cat, or your broken headlight after an accident. Spot Metering Mode When you look through the lens of a DSLR there are typically a series of focus points and/or centre-ing marks; these are small, sometimes selectable areas within the frame from which the camera then samples light to determine the exposure – “the spot.” Any light that falls out of the designated spot is effectively ignored during the exposure value calculation. This setting is ideal for when the subject is small within the frame or the lighting on background objects competes with the main subject and you need to zero in on what has captured your eye. Many cameras allow the user to choose which mark is the spot, thus giving you more flexibility and control. Partial Metering Mode Partial Metering is a camera-metering mode in which the metering is weighted at the center of the viewfinder (unlike center-weighted in which the camera averages the exposure based on the reading at the center). You can think of Partial Metering as “expanded” spot metering, because the area that is metered is specific, but not tiny (roughly 10% of the viewfinder versus 2.3% of the viewfinder for spot metering mode). Partial metering is best used when your subject is overly backlit and you want to get a quality exposure of the subject. Partial metering will enable correct exposure of your subject, however the background will be over-exposed. Partial metering will enable you to more specifically control the exposure in a particular region of the photograph. Multi-Zone Metering Mode Multi-zone metering (also called Matrix, Evaluative metering) is the generic default setting in which the TTL meter uses light from all points in the frame and then the camera makes an approximation as to what’s most important when calculating the exposure value. The effectiveness of the matrix in question has a lot to do with the internal computer and how many matrix points are present (for example 6-point or 9-point matrix). This basic setting is the most non-discriminating and therefore is most useful in situations where the lighting is most uniform – like a landscape – and there aren’t any excessive highlights or dark pockets that could “trick” the sensor. Recommended Settings First examine the picture through the viewfinder. If it looks evenly lit, use the evaluative or Multi Zone metering mode. If the person or subject to be photographed has a bright light source like the sun behind them, use centre-weighted average metering mode. If your subject is the most significant part of the picture, use spot metering mode - also referred to as ‘partial mode’. Just ensure that you aim the metering mode icon in the centre of your camera’s viewfinder- at your subject. White Balance Understanding White Balance in Digital Photography White balance (WB) is considered as one of the most important settings of a digital camera. Let’s consider a scenario where you want to capture the beauty of sea waves hitting the shore with an overcast sky at the background. Sounds interesting? Well, if you don’t use the correct white balance setting of your digital camera, you may get a picture with colours different from the actual ones. Therefore, in order to produce a beautifully exposed image with true to life colours, you must learn to effectively use the white balance setting of your digital camera. Color Temperature To understand the concept of White Balance, you need to first understand the concept of colour temperature. Colour temperature is a characteristic of visible light. It provides a method of describing these characteristics and is measured in Kelvin (K). A light having higher colour temperature will have more blue light or larger Kelvin value as compared to lower light, which has a smaller Kelvin value. The following table shows the colour temperature of various sources of light How does the Light Affect the Color? You may have noticed some photos turn out with an orange/yellow cast if shot under tungsten lighting or a bluish cast if shot under fluorescent lights. This occurs because each source of light possesses a different colour temperature. A digital camera can measure the colours in the red, green, and blue light of the spectrum, as reflected to its sensors. In a photo taken under the midday sun there is the whole spectrum of light (which makes up “white” sunlight). Under these conditions, the colours in an image appear nearest to the “true” colours.
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