Lesson 13: White Balance

30 October 2009

White BalanceWhite balance is a digital camera setting that allows the colors in your photos to appear accurately. White balance gets it’s name because if a photo has correct white balance, things that are white in reality appear white in the photo. All other colors appear accurately too – blacks are pure black and gray are pure gray with no other colors mixed in.

Why do we need white balance? Different light sources produce different colored light. For example, household light bulbs contain a gas called tungsten which produces an orange colored light, flourescent bulbs produce a greenish colored light, etc.

You’ve probably seen photos with incorrect white balance that were taken indoor without a flash. These photos tend to take on either a green or orange tint depending on what kind of lights are in the room. This happens because the camera sees the world differently than the human eye. While our eyes are able to automatically correct colors accurately, the camera is not capable to do that.

Correct white balance is important for many reasons. In portrait photography skin tones need to appear accurately because greenish or yellowish skin tones look unnatural. In product photography it is important for the colors to appear accurate so that the consumer knows exactly what he is getting. Also, when taking multiple photos of one thing it’s important to have consistent white balance so that the colors in the photos all match.

So what white balance should you use? In order to get the most faithful color representation you should use the SAME white balance mode as your MAIN source of light. For example, if your house is lit by 5 flourescent lights and and one regular light bulb – you should set your camera to flourescent white balance. If you are inside during daytime and all the windows are open and only one light bulb is on, you should probably use the daylight white balance. If your camera has a custom white balance setting then you can take a picture of a white paper and take the white balance from that picture. This is one of the most accurate mode to set the white balance. See your camera manual to find out how to do that. Experiment and don’t be afraid to make mistakes. Learning to use white balance properly takes a lot of practice.

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ModesAPERTURE PRIORITY MODE (A or AV): This mode is really a semi-automatic (or semi-manual) mode where you choose the aperture and the camera chooses the shutter speed so as to ensure you have a well balanced exposure. Aperture priority mode is useful when you’re looking to control the depth of field in a shot (usually a stationary object where you don’t need to control shutter speed). Choosing a larger number aperture means the aperture is smaller and lets less light in. This means you’ll have a larger depth of field (more of the scene will be in focus) but that your camera will choose a slower shutter speed. Small numbers means the opposite (if your aperture is large, depth of field will be small and your camera will probably choose a faster shutter speed).

SHUTTER PRIORITY MODE (S or TV): Shutter priority is very similar to aperture priority mode but is the mode where you select a shutter speed and the camera then chooses the aperture. You would use this mode where you want to control over shutter speed (obviously). For example when photographing moving subjects (like sports) you might want to choose a fast shutter speed to freeze the motion. On the flip-side of this you might want to capture the movement as a blur of a subject like a waterfall and choose a slow shutter speed. You might also choose a slow shutter speed in lower light situations.

PROGRAM MODE (P): Some digital cameras have this priority mode in addition to auto mode. In those cameras that have both, Program mode is similar to Auto but gives you a little more control over some other features including flash, white balance, ISO etc. Check your digital camera’s manual for how the Program mode differs from Automatic in your particular model.

MANUAL MODE (M): In this mode you have full control over your camera and need to think about all settings including shutter speed, aperture, ISO, white balance, flash etc. It gives you the flexibility to set your shots up as you wish. Of course you also need to have some idea of what you’re doing in manual mode so most digital camera owners tend to stick to one of the priority modes.

ApertureI’ve decided to talk about Exposure Time and Aperture in the same lesson because it is a strong relation between them, which I’ll explain later. First I will discuss about each of them to help you understand them better.

EXPOSURE TIME: The Exposure Time is the period of time in which the sensor will be exposed to light. This is done in the moment push the button to take the picture. A mechanism inside the camera will open for the precise amount of time that has been manually set or automatically calculated by the camera. The exposer time on a digital camera can vary in a wide range. For example, on my Canon 450D DSLR the exposure time interval is from 1/4000 to 30. That means that I can expose the sensor from the tiny amount of time that is 1/4000 of a second up to 30 seconds. This is set accordingly to light conditions where the picture is taken.

APERTURE: This is a little more complicated to understand than exposer time, but I’ll try to explain it as simple as I can. The aperture is a characteristic of lenses and it is usually specified on these as a value like 1:3.5-5.6 (on lenses with zoom capability) or 1:1.8 (on lenses with no zoom). To make an analogy with the human eye, aperture is similar to the pupil. It gives us the ability to set the amount  of light that enters through the lens by closing or opening a mechanism similar to the eye pupil. A smaller number means a wider opening so more light will come in. The numbers specified on lenses means the maximum opening of the aperture that can be achieved. For example a value like 1:3.5-5.6 (or f/3.5-f/5.6) on some zoom lenses means that we can get a maximum aperture opening of 1:3.5 (or f/3.5) on no zoom and a 1:5.6  (or f/5.6) one on maximum zoom.
Another very important aspect about aperture is the Depth Of Field (or DOF). Depth of field is a term which refers to the areas of the photograph both in front and behind the main focus point which remain “sharp” (in focus). Depth of field is affected by the aperture. A larger aperture (smaller f-number, e.g. f/2) has a shallow depth of field. Anything behind or in front of the main focus point (the main point that you want to be sharp) will appear blurred. A smaller aperture (larger f-number, e.g. f/11) has a greater depth of field. Objects within a certain range behind or in front of the main focus point will also appear sharp. Here is an example:

DOF

The relationship between aperture and exposure time is that a smaller aperture will result in less light that will enter through lenses, so a longer exposure time will be required and vice versa. So you can achieve the same luminosity in a picture using different aperture/exposure time combination. The main reason for playing with these two is again the DOF (Depth of Field). There are many situations when you want a shallow DOF (so a blurred background), like in portraits, macros, etc, and there are situations when you’ll prefer a greater DOF, for example in landscape photography. To master this two in combination will require time and a lot of exercises, but I assure you that it worth the effort.

Lesson 10: Automatic modes

25 October 2009

ModesSo now you have your digital camera in your hands and you are about to take the first shots. Most beginners in this situation will put the camera into full auto mode, or into one of the auto mode presets. In this lesson we will talk about these modes so you can know their advantages and their limits.

AUTOMATIC MODE: Auto mode tells your camera to make all the adjustments to take the best shot that it can. Some cameras lets you make your own settings for flash or red eye reduction. This mode will give you nice results in many usual shooting conditions, however you need to know that you’re not telling your camera any extra information about the type of shot you’re taking so it will guess what you want. As a result some of the following modes might be more appropriate to select as they give your camera a few more hints without you needing to do anything more.

PORTRAIT MODE: When you switch to portrait mode your camera will automatically help to keep your background out of focus. Portrait mode works best when you’re photographing a single subject so get in close enough to your subject or use the zoom function so that your photographing the head and shoulders of them. Also if you’re shooting into the sun it will be a good ideea to trigger your flash to add a little light onto their face.

MACRO MODE: Macro mode lets you move closer into your subject to take a close up picture. It’s great for shootinginsects, flowers or other small objects. Different digital cameras will have macro modes with different capabilities that includes different focussing distances, usually between 2-10cm for point and shoot cameras. When you use macro mode you’ll notice that focussing is more difficult as at short distances the depth of field is very narrow. Keep your camera and the object you’re photographing parallel or else you’ll find that a lot of it will be out of focus. A tripod is very useful in macro shots as the depth of field is so narrow that even moving towards or away from your subject slightly can make your subject out of focus.

LANDSCAPE MODE: This mode is almost the exact opposite of portrait mode in that it sets the camera up to make sure as much of the scene you’re photographing will be in focus as possible. It’s ideal for capturing shots of wide scenes, particularly those witch points of interest are at different distances from the camera. Your camera might also select a slower shutter speed in this mode so you might want to consider a tripod or other method of ensuring your camera is still.

NIGHT MODE: This is a fun mode to play around with and can create some interesting shots. Night mode is for shooting in low light situations and sets your camera to use a longer shutter speed to help capture details of the background but it also fires off a flash to illuminate the foreground (and subject). If you use this mode you should use a tripod or your background will be blurred – however it’s also fun to take shots with this handheld to purposely blur your backgrounds – especially when there is a situation with lights behind your subject as it can give a fun and experimental look.

These are the most important fully automatic modes. Different digital cameras can have more additionall modes but they are not so commonly used. In the next lesson we will talk about shutter speed and aperture so we can talk later about the semi automatic modes.

Lesson 9: Batteries

21 October 2009

Rechargeable BatteriesBatteries are another very important aspect that you will have to take into consideration. Some digital cameras (mainly the DSLRs) come with their own rechargeable batteries, so the only thing you can do after you get your camera is to see if this one is enough for you and if not, you can buy another one (or more), so you can change them in case you need to. If the camera doesn’t come with it’s own rechargeable battery then in most cases it will be compatible with standard AA ones. Choosing which one to buy can be a discouraging job since there are so many models on the market today. This can be very much simplified if you take into consideration this two aspects:

1. Number of mAh (milliampere-hour): This is a characteristic of rechargeable batteries that tell us how much current can they give. The bigger the value is, the longer the batteries will resist until you will have to recharge them again. Common good values today rise from 2500 mAh up.

2. Recharging device: The main thing that is important about these devices is the speed of recharging. It is not as important as batteries capacity, but sometimes can matter a lot. Basically there are two categories: normal rechargers and fast rechargers. With the first ones you can recharge your batteries within approximately 12 hours, sometimes more, which is a considerable time that can be very important in some situations. The second ones, on the other hand, can recharge your batteries in about 3 hours, some models even faster. The fast recharging is also a recomanded way to do it.

I hope these informations will make the job of choosing the right rechargeable batteries a lot easier for you.