PHILANTHROTOGRAPHY PHOTO 101: BASICS
WHAT IS AN SLR? Single Lens Reflex camera • • • •
You see what the lens sees Can change lenses Have large image sensors for high-quality images Near-zero lag time
Bottom line? Digital SLR cameras are versatile.
ANATOMY OF AN SLR
• Light passes through the lens and strikes a mirror (green) • The mirror reflects the light up to a focusing screen • Light passes through the focusing screen and enters a block of glass called a pentaprism (orange) • The pentaprism reflects the image so that you can see it in the viewfinder • When you take a photo, the mirror flips up and a shutter (blue) opens that exposes the digital sensor (red) to light By using the viewfinder you can precisely compose your image and adjust the focus—you see what the lens sees.
EXPOSURE & THE PHOTOGRAPHIC PROCESS When you press the button on your camera, you are literally “exposing” it to light. All photography is captured light. Without light, there is no picture. We don’t see things we see the light reflected off things. When we take a picture, what we’re really doing is recording the light reflected off whatever it is our camera is pointed at. That is the exposure. A camera, at its most basic, is nothing more than a light-proof box. It has an opening that is covered up by a light-proof curtain called the shutter. Directly in front of the shutter is where we put the lens. When you press the button on your camera to take a picture, what happens is that the shutter opens and exposes “the film” to light for a specified period of time. The film is so sensitive to light that this very brief exposure is all that it needs in order to see and record whatever was in front of the camera when the shutter was opened.
EXPOSURE TRIANGLE 3 • • •
Main factors impacting exposure Aperture Shutter Speed ISO
Think of exposure as a perfect triangle – all the angles are equal, all the sides are equal. Now if you change just one part of that exposure or triangle, it is no longer perfect so you will need to change another point of the exposure or triangle an equal but opposite amount to make that triangle and therefore the exposure perfect again All the elements of exposure have a different effect on the image.
APERTURE 1. Controls the amount of light that is allowed into the camera through an opening in the lens 2. Measured in f-stops. 3. Determines the Depth of Field. 1. Aperture is an adjustable opening in the lens used to let more or less light hit the digital sensor or film. Think of window blinds as your aperture, and the wall in your room opposite the blinds is your sensor or film. As we open the blinds, more light comes through and we can see the wall behind us get brighter and brighter. Likewise, as we open up the aperture on our lens, we get more light on our sensor or film. 2. Think of aperture openings, or f/stops, as the bottom number of a fraction. So if we have f 4 that would be 1/4 and f8 would be 1/8 and 1/4 is larger than 1/8. The Aperture numbers represent “Whole Steps� of light from one to the next. A whole step represents the doubling or halving of the light through the lens. So f1.4 will let in twice as much light as f2.0. f2.0 twice as much light as f2.8 or we can also say that f2.8 is half as much light as f2.0. On your lens, you may see numbers in between the numbers above. Those represent 1/3 stops so we can fine tune beyond just whole stops. f/1.4 has a very wide opening, whereas f/11 is much smaller. Always remember: the smaller the numerical value, the larger the opening in the lens, and the brighter your photo will be. 3. The aperture is responsible for the Depth of Field (DOF). This is how sharp the focal point in the picture will appear, and the amount of blur that other areas will take on. The relation between the diaphragm, depth of field and f-number is pretty simple: wide open aperture, less depth of field and conversely, small aperture opening grants a greater depth of field. So, with f1.4 selected, the blades of the diaphragm are wide open letting more light pass through and we get a poor/shallow depth of field. As the f-number increases, the diaphragm blades reduce the aperture letting less light pass and resulting in a greater depth of field.
DEPTH OF FIELD Depth of field is the amount of the frame that is in focus. The amount of depth of field that you can achieve will depend on your camera, lens and available light. Factors that affect Depth of Field: 1. Aperture 2. Distance between camera and your subject 3. Focal length of your lens (50mm, 200m etc). More on this in another lesson 1. A large depth of field such as f22 will keep all or most of the frame in sharp focus, while a small depth of field such as f4 will have a smaller area in focus with the rest of the image blurred. Photographers that shoot portraits usually use larger apertures (low numbers) for a shallow DOF to highlight and isolate their subjects. Landscape photographers usually use small apertures to have a very deep DOF, all the way from the foreground to the background. As usual, there are exceptions to these rules and that is ruled by the photographer’s artistic ideas and vision. f/4 = Large aperture. More light allowed through the lens. PORTRAITS f/22 = Small aperture. Less light allowed through the lens. LANDSCAPES 2. Depth of field is also effected by the distance that the main subject of focus is from the lens. For example if shooting a subject from a mid to long distance with a large aperture of f4 will produce similar results that a small aperture would produce. Whilst shooting from a short distance will produce clearly visible differences. In bright light you may have to select a smaller aperture or faster shutter speed to prevent over exposure, while in low light the aperture can be kept wide open to let more light in, allowing you to use a faster shutter speed or avoid using a flash.
ISO 100
F 2.8
SS 1/640
ISO 100
F 32
SS 1/4
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SHUTTER SPEED 1. 2. 3.
The amount of time light passes through the lens to expose the image sensor or film. Affects perceive motion in images. Allows you to stop motion or highlight motion Measured in fractions of a second
1. The shutter speed is the length of time light passes through the lens, or the time the image sensor in the camera is exposed to light. The longer the time, the more light will hit their surface. This time directly affects the illumination degree in a photo, which is the reason we use the term underexposed when a picture is too dark and overexposed when it is too bright. In both cases the problem was incorrect exposure time. 2. shutter speed controls motion. Whether we want to freeze motion or show motion, shutter speed is the portion of exposure that will control that aspect. 3. Shutter speeds are measured in fractions of a second. For example if you see a 500 speed available, the time the shutter remains open is 1 / 500 or 0.002 seconds. A shutter speed of 2 means the shutter remain open for half a second. If you see quotation marks on the right side of a number (like 1″) it means the shutter will remain open for a full second, so please take a good look when selecting the speed since 2″ is very different from a single 2. The former means the shutter will remain open for two full seconds and the latter, as we said before, will remain open for just half a second. In some cameras you can also find a “B” or “T” speed available, these letters stand for: B (Bulb): Keeps the shutter open until you release the button. T (Time): Keeps the shutter open until you press the button again.
SHUTTER SPEED 1/60; f/13; ISO 200
1/500; f/4; ISO 200
ISO 100 F-32 SS 1/4
ISO 100 F-11 SS 1/30
ISO 100 F-2.8 SS 1/640
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How to choose your settings Small aperture = Large f-stop (f/16, f/22, f/64) Large depth of field. All or most of the frame in sharp focus. Large aperture = Small f-stop (f/1.4, f/4) Small depth of field. Main subject in focus, background and/or foreground blurred Fast shutter speed = 1/125 -1/1000 Slow shutter speed = 1/60 - 30 seconds or timed (B) Bulb exposure. Ask yourself, what is your priority: motion or depth of field? MOTION: • Do you want to stop motion or emphasize movement? • Can you hand-hold the camera at this shutter speed and not have the slight movement of the camera show up in our image making it blurry or less sharp? DEPTH OF FIELD: • Do you want more or less depth of field? • How far are you from your subject? Do you have enough light to realize your vision, or do you need to compromise settings?
Fast shutter speeds can have the disadvantage of only allowing a large aperture due to the available light, this can reduce the depth of field of the shot, an advantage is that camera shake is almost certain to be eliminated in normal conditions.
In contrast a slow shutter speed can cause overexposure (too much light) even with a small aperture, and camera shake will be a problem. There are a few simple rules that you can follow to combat this. Firstly a tripod must be used for slow shutter speeds eliminating camera shake. Compensating overexposure is a little more tricky, if you have a minimum aperture and still getting over exposure then you will need a slower film ISO or ISO setting (digital) and or a lens filter, Neutral density (ND) or ND gradient filters are used to reduce the amount of light entering the lens. Polarizing filters will also help reduce the amount of light entering the lens. Another step you can take is to Photograph subjects that requite a slow shutter speed, in low light conditions, such as early morning or late afternoon evening. More on filters here The speed range for running water is 1/15 - 5 seconds, however exposures of greater than 5 seconds may be used in the right conditions, giving more blur, this can be especially good for slow running water. Using a fast shutter speed (short exposure) will freeze a moving subject, whether it is running water or a racing car, the latter will need a faster shutter speed due to the velocity. 1/125 second is usually enough to freeze water giving it a crystal effect. where as a racing car may need a shutter speed of at least 1/500 second. This will differ depending on the relative speed, distance and whether the subject is travelling toward you or across the frame. Using a slow shutter speed (long exposure) will have the opposite effect, running water will become a silky blur, slow shutter speeds are not suitable for sport unless you are looking for a special effect.
ISO ISO is the sensitivity to light of the sensor or film. The higher the sensitivity, the less time (shutter speed) or the less amount of light (aperture) needs to hit the sensor for the correct exposure. It is adjustable in most cameras, in a range of about 200 to 1600. High end cameras can go way beyond that. ISO is the third part of the exposure triangle and works in tandem with shutter speed & aperture. Similarly, there are advantages and disadvantages for each shutter speed so decisions must be made by the photographer to achieve the desired effect. Your objective should be to use the lowest ISO possible, but balanced with the desired outcome (unless you like grain and noise)
Low sensitivity, ISO 25 – ISO 50 Pros: Excellent definition and great contrast, the best range to use when you need to amplify an image. Cons: Used in places with good illumination only. Think beach or studio Medium sensitivity, ISO 100 – ISO 400 The most popular range for beginners and professionals, maintains a good proportion of definition and contrast and can handle decent amplifications. Used in places with normal illumination. High sensitivity, ISO 400 – ISO 3200 Pros: Ideal for indoor photography, night shots, concerts. When using with flash you can achieve greater depth. Cons: Contrast and definition can be a little poor, and the big grains associated with high speeds are notable (meaning your photos can appear pixelated).
PUTTING IT ALL TOGETHER
 Every scene we photograph has a dynamic range: the difference between the brightest and darkest parts of your scene A camera sensor or film has a dynamic range too. What we hope to accomplish is to capture that dynamic range of the scene into our image so that the brightest part of the image (say the sky) is not blown out and devoid of detail, and the darkest part (shadows or foreground dark areas) are not lost into noise. Sometimes the dynamic range of a scene can exceed the dynamic range of our camera, so we have to make a choice of what part we want to have the best exposure. Usually with digital it is best to have the brightest areas in good exposure and not blown out. But it can depend on the situation. If we are shooting a portrait, we want our subject to be perfectly exposed even if that means that another part of the image my not be. Some times that is a sacrifice we have to make, if we cannot change the conditions of the shoot nor have the option of supplementing the lighting.
There is not a right or wrong method, it is simply a matter of preference, and achieving the effect that you desire The best way to completely understand shutter speed and aperture is to put your camera in Manual mode, and experiment! Your settings will depend entirely on what you are shooting, your shooting environment, and how you want to expose your photo. If you want a shallow depth of field, but do not want to overexpose your photo, you will need a wide aperture (f/2.8, for example), and a fast shutter (somewhere around 1/125). If you want to capture a wide range of focal points, you will need a smaller aperture (f/11), and a slower shutter speed (1/80). REMEMEBER, these settings all depend on your environment and what you are photographing, so be sure to experiment with different settings. So how do you determine what settings are appropriate for you environment? LIGHT METER
LIGHT METER Illumination is the key factor in photography; according to it we select the ISO, define the SHUTTER SPEED and regulate the APERTURE to properly expose the image sensor. The device that measures the amount of light in the environment is your light meter. It measures the light that passes through the lens and lets us know if it is adequate or whether we need to make some adjustments. If your camera displays a photo meter you should be able to see a little indicator like the following: - 2 …. 1… . 0…. 1 ….. 2 + An indicator will let you know you if your current settings are right, normally if it’s around “0″, you are ready to shoot. If the indicator is at the right, the positive side, it means there is too much light. If it is on the left side, the negative, it means you need to let more light pass though. In both cases you can change the current ISO, shutter speed or aperture until the indicator is around the 0 – it really is up to you which one to move. In cameras, this metering is called TTL (Through The Lens), calculating the light reflected from the object. The most common modes are matrix and spot. The first one calculates the average light in the entire scene, like pieces in a puzzle, and each one has its own value. The second one just meters the spot you are pointing at and excludes all of its surroundings.
LIGHT METER
CAMERA CONTROLS How do you identify SHUTTER SPEED & APERTURE on your camera? • Most DSLRs have a dial with manual controls: PASM or P/Tv/Av/M • Take your camera out and half-press the shutter, two numbers should pop up: One might have an f in front of it (ie. f3.5) or it will be a decimal of sorts (ie. 4.0). That number is the aperture. The other number (if you're outside) should be larger, say around 200-4,000. That's the shutter speed.
When the meter can be wrong Meters measure light reflecting off of an object, then calculates what it thinks the best exposure will be by averaging tone of your picture. Sounds simple, but they can easily be fooled in some instances, leading to bad exposure Imagine that you have a black cat and a white cat sitting next to each other. The ambient light level, and the optimum exposure, is the same regardless of which cat you take a photo of. But if you move in close and take a photo of the white cat, your camera’s meter will give you a very different suggested exposure setting than if you had chosen the black cat. That’s because the fur of the white cat reflects more light. Why does the camera’s meter get it wrong? The reason is that the camera expects all the tones within the scene that it is metering to average out to a mid-grey tone (also known as 18% grey). In practice, you may often find yourself photographing subjects that aren’t typical. That’s when the camera gets the exposure wrong. If your subject has a lot of light tones (sand, snow, white cat/dress/building, etc) your camera will underexpose the image (the photo will be too dark). And visa versa with an average of dark tones in an image, your origin will be too bright. 31
BRACKETING bracketing allows us to cover a range of exposure settings for a single shot. You can set your camera to take a series of images according to a bracket range you specify, or you can do this manually. For example, you might setup your bracketing to make a -1, 0, and +1 (or one stop under, normal, and one stop over exposed) series of shots. Be careful to reset or turn off bracketing when you don’t intend to use it or you might be surprised by unexpected exposure results.
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SHUTTER SPEED FAST, stop motion SLOW, motion blur
ASSIGNMENT: Make two photographs of a moving subject using two different shutter speeds, fast and slow, to show stopmotion and motion blur. Take note of your settings. Pre focus or zone focus for action shots. Focus for 3 feet in front and when the action arrives there, take the shot. Great for shooting from the hip street photos
APERTURE WIDE, less depth of field CLOSED, more depth of field
ASSIGNMENT:
Shoot the same subject using two different aperture settings: large f-stop for greater depth of field and small fstop for less depth of field. Take note of your settings.