Intro 2 Photography
Content
Int ntr r o d uct uc t i o n to t o Photography
Author
Abhijit Ray
Page 1 of 25
11/6/2007
Preface The objective of this book is to introduce the basic aspects of photography to absolute beginners. Normally everybody goes to buy a camera and then some of them think of understanding what the camera can do and why the camera does what it does. I have tried to explain the various aspects of the SLR camera. This document is aimed at educating you about photography while helping you to decide on your very own photgraphy gear. I would have loved to add some of my own pictures as examples but then the size of this document will in megabytes and it would not have possible to get this document as a mail attachment. Instead, I have drawn the some pictures to illustrate the examples and have thrown in a few light weight photos for illustration. Even though pictures could not be provided for everything, I have described every point in a bit of detail. I hope you can relate the contents in this document with your camera and your photographs. The details given in this document are sufficient to start a novice off. The document will provide the foundation of your knowledge, which you can farther later on. All the best on your new and exciting journey….
Page 3 of 25
11/6/2007
Introduction To buy a camera we first need to understand a camera. Only then can we make the right decision. I have had various people coming to me and asking for my advice before buying a camera. In most cases I have seen that their idea of buying a camera is to go for the most expensive camera their pocket permits. Yes, this is true. We have to stay within our financial limits but that does not mean that buying the most expensive possible camera within our limit is the best choice. We have to know why we are buying the camera, how we are going to use it, for what. For example, most of us buy a camera to take travel photographs, on social occasions. This means a relatively cheap camera with 2 inexpensive lenses will suffice. Again there are people who buy a camera to take good photographs. They require a different camera and different lenses. The aim of this document is to give an insight into the various aspects of a camera so that all of you can make the best possible decision yourselves and after buying the camera you shall also understand the various features of it.
Myths Myt hs about SLR SL R cca ameras Those who have come to me asking about the benefits of a SLR always ask me keeping in mind that I’ll be giving them the advantages of a SLR over a compact camera. Everyone has the idea that a compact camera is cheap and very handy, easy to use, aim and shoot whereas an SLR is that complicated and difficult ……… is not completely true. and you have to know a lot about photography to use it, but
A dvantag dvantages es o off S SL L R cameras over ccompact ompact cameras SLR Camera There is only one lens so whatever you see through the lens is the whole object which is going to be captured on the film With these cameras you have option of adding a lot of accessories that will help and/or enhance your photographic options. Eg, add a better flash gun, or different lenses, or filters These cameras are sturdy. Thus their weight is more.
Compact camera These cameras have 2 lenses, one for viewing and one for the film. So for close objects you do not get whatever you see, on film With these cameras you have no option of adding any accessories. You can only use whatever is on the camera. These cameras have flimsy bodies and so they are lightweight. These have to be handled very
carefully. Can take photographs in all conditions, These cameras can take photographs in fixed lowlight, extremely bright, rain, haze, cold, hot conditions only. Nowadays, compact cameras etc. provided the right accessories are present. are more advanced but still they do not come close to the flexibility of SLR cameras.
Why should you you b buy uy a SL R ca cam mer a? OK, this question still lingers in your mind. Compact cameras are so easy to carry around but SLR cameras are heavy, there is a considerable amount of time needed to learn about the cameras, you have to waste a lot of film to take a considerable good photograph. Right? WRONG!!!!! Amazingly enough, today the SLR cameras can be used just like a compact
Page 4 of 25
11/6/2007
camera, i.e. like a point and shoot camera but with better image quality and still have all the flexibilities and advantages that a compact camera has. The main problem with compact cameras is that it decides what you can do and not the other way round. “But what about cost? SLR cameras cost way too much. Compact cameras are less expensive and very affordable.” TRUE. Let’s look at a live example. The lowest price of a SLR camera in 2001 was Ł180 and a somewhat ok compact camera was about Ł100. But judging the benefits of both I would say it is better to go for the SLR as buying a camera is a one-time investment. So if our pocket permits it is better to spend a little better and get something which will besome a pleasure losing shots. throughout our lifetime rather than save some money now and moan about So have we decided on a SLR yet? Yes? Ok, now let’s see how to go about choosing the right camera that suits not only our budget but also our passion for photography. First let us see how many types of cameras exist on this planet.
Don’t rush to the store!!! Have you gone through some photography magazines? Could you understand all those figures about photos? Do you understand when a particular picture is referred to as “Taken at 60 and f/5.6”? If your answer is no. …read on …. Let us understand a few points about photography so that you can understand the jargon the salesmen at the store say and once you’ve bought your own machine you’ll be able to shoot confidently from day one.
Types of cca ame mera ra There are various kinds of camera. 1. TLR ( Twin Lens Reflex) 2. SLR (Single Lens Reflex) 3. Rangefinders 4. Compact TLR cameras and Rangefinders are nearly extinct nowadays. So I will not go into the details of those kinds of camera. Here I shall stick to SLRs’ only and sometimes I shall pick up references from compact cameras, as these are very popular now. OK, SLR SLR stands for Single Lens Reflex. Reflex . Why Single and what Reflex? Yeah, I know you’re thinking about that already. I’ll come to that a little later. These are generally 135 film cameras (those cameras which almost everybody has). There are other SLR cameras that use 120 films. . Note:: 120 or 135 are just a number for denoting different sizes of films Note
Page 5 of 25
11/6/2007
SLR Internals Let’s look at the cross section of a SLR camera. Below, the path of a light ray is shown. This is the condition when we look through the lens for viewing only and not w h i l e the photograph is being taken. When the photograph is taken then the mirror goes up and meets the bottom of Pentaprism the pentaprism and light ray falls directly Eye S onto the film thus creating the image. At h u this point of time the photographer is t t e unable to view the subject because the r p l light rays no longer reach the eye of the a Path of a light ray F n e photographer. Once the photograph is i l m taken the mirror comes back to its p l a original position. Thus the camera is n e called a reflex reflex camera and since the camera has one lens the name becomes S in ingg le L ens R eflex . Another thing Mirror Lens happens when the photograph is taken. There is a shutter in front of the film plane. The shutter opens and the light falls on the film, creating a latent latent image on the film. This image formed is called latent because until the image cannot be seen until the film is developed.
What is a latent latent image? image? A latent image is the image formed on the film once light falls on it. It is called latent because the image is not viewable until it is developed in a lab.
Page 6 of 25
11/6/2007
Aspects of photography ·
Shuttter sp Shut spe eed
Question. speed? OK, imagine you are in a completely dark and closed Question. What is shutter speed? OK, room. There is a window that can be opened only for a moment. To see the outside world this window has to be opened. Once this window is opened the view is seen for a moment. So even if there is a car moving at top speed outside the car will seem to be static as this window opens just for a moment. This is exactly what shutter speed is. The SLR is the dark and closed room and the window is the shutter. The shutter in a camera opens and closes according to the speed which the photographer sets. Once the shutter opens, light falls on the film and the latent image is formed. Now the shutter can remain th th open for say 1/60 of 1 sec or 1/125 of 1 sec. This is called shutter speed. If the duration is th 1/60 of 1 sec then it is referred to as 60. So shutter speed is the reciprocal of the duration of the open shutter . This is not so important to you as a photographer. What is important to you is the implication of the whole thing and all the things that it affects. Any camera produced in the world will have a range of shutter speed like this,
Shutter speed range 1000 500 125 speed implying increase Shutterspeedwit ith 60 in light falling on the film, durationl tionlessthan1sec 30 i.e. shutter speed of 60 15 allows double the light 8 allowed by shutter 4 speed of 125 and half 2 Shutterspeedwit ith the light allowed by 30 1 duratio ionmorre ethan1sec 2 4 Shutter speed increases or decreases a factor of 2. It means that changing the speed from 30 to 60 means higher speed. It also means that the duration increases from 1/30 sec to 1/60 sec. Similarly changing the speed from 30 to 15 means lower speed, change from 1/30 sec to 1/15 sec, which means higher duration. In terms of photography we refer to as higher or lower speed and not duration. duration. This change of one step higher or lower is also called “changing one stop
Dec rea sing shutter shutter
(higher/lower)” in photography jargon. W e see that one stop change increases or decreases the shutter speed by a doubled.. In the previous factor of 2 and so the light that enters the camera is also halved or doubled example changing shutter speed from 30 to 60 increases speed by 2 and so light falling on the film is halved. On the other hand change from 30 to 15 allows double the amount of light to enter. So this shows how the amount of light can be manipulated just by changing the shutter speed. Thus light can be changed 4 times by a change of 2 stops ( 2 X 2 ), 8 times by 3 stops ( 2 X 2 X 2 ) and so on.
Understanding shutter movement Before taking the shot. (both shutte tters together) Fig.A
The shutter is made up of 2 shutter curtains, one in front of the other. If we open the back of the camera then this is what we’ll see. Suppose now, we’ll open the back of our camera(which does not have any film loaded) and fire a test shot. Then we’ll only get to see one shutter curtain, i.e. the one that faces the film
Page 7 of 25
11/6/2007
Shutter 1 Shutter 2 Fig. B
Light sl slit it
Fig. C
(Shutter1) and not the one that faces the lens (Shutter2). Fig A shows this very condition. Here we are assuming the names of the shutter curtains for our understanding. Once the shutter is pressed Shutter1 starts moving up but Shutter2 remains static (fig. B). Only after a certain amount of time does Shutter2 start moving up. So a thin slit is formed between the shutter curtains. This slit of light isallows light the Itfilm latent image formed on on thetofilm. is and as ifthus lightthe from the scene is sprayed all over the film. After the photograph is taken Shutter2 comes in front of the film. On autofocus cameras, the film is then wound and the next frame comes into position and Shutter1 and 2 go back to their original position. On manual cameras this is done manually when the film-winding lever moves the film to the next frame.
Why have this kind of mechanism? This mechanism is very useful because with just Shot complette e. ((A Again in one curtain it would have been impossible to have fast both shutters ters shutter speeds. together but in We know that in SLR’s the shutter guards the reverse order) film from light when we see through the lens. Suppose the camera had only one shutter then Fig. D the shutter has to open first and then close the frame. Now if we take a photograph at shutter speed 500 then the shutter had to move twice. th That means the shutter had to move at a speed of 1/1000 of a second. This would mean more wear and tear of the curtain gears. With the 2-curtain mechanism there would be no need for that kind of movement. The speed of the curtain would be the set shutter speed. When we use a lower shutter speed, Shutter2 starts after Shutter1 has moved up for quite some time and for a higher shutter speed it is just the opposite. Hence for a higher shutter speed the slit is smaller in width and vice versa for slower shutter speed. If we start from the top shutter speed and keep on coming down, there will be one value for which Shutter2 will start after Shutter1 has moved up, leaving the frame completely open. This shutter speed is called the Flash Synchronisation Speed Speed
Flash synchronization speed the maximum speed should be used during This flash is photography. This shutter is different for that different cameras. It is generally 60/90/125. If a camera has synch speed of 90 then photos with the flash should be taken with a shutter speed of 90 or less than that. On some advanced autofocus cameras combined with dedicated flashguns, there is no flash synchron synchronizati ization on speed. This will be discussed in detail when we discuss flash photography photography..
Page 8 of 25
11/6/2007
·
Ap A perture
Now this is not directly related to your camera. Actually, this is a feature of the lens. Just like shutter speed, aperture also has a range of values. A typical range of values looks like
Aperture range 45
Onl ons ecialisedlenses
32 32 22 16 Availableonal typesof 11 lenses,zoomor fixedfo dfocal 8 lengthlenses 5.6 4 2.8 AvailableonlyonNorrm malle lenses,very ry 2 expensiiv ve/ specia ialilisedz zo oomlensesand 1.8 fixedfo dfocallengthl hle enses 1.4 1.2 1 Aperture is denoted as f. An aperture of 5.6 is denoted as f/5.6. Aperture is in plain English is a hole. In photographic terms it does go to mean just that but it is simplified to an extent
Decrease in f value or increase in aperture implying increase in light falling on the film, i.e. a pe perrtur ture e 5. 5.6 6 or f/5.6 f/ 5.6 allows half the light allowed by aperture 4 or f/4
so that it can be related light. So from common sense we get thatallows a larger means more light coming in. But to it seems paradoxical here as a higher value lessaperture light (see chart above). What does this mean and how does this come about? Let’s see what the aperture looks like. When you take the lens off the camera or you open the camera back you’ll see something like this
Theouter shell of thel ele ens (the plasti lastic/ c/m metal part). This is the thep part whichh chholdsth thelenselementsiin nplace Theback of thel ele ens (glass) We shall look at the lens back because that’s where the aperture comes into play. From the picture in the left we can see how the aperture is made. There is a group of curved blades (in the picture the blades are shown as straight edged) which rotate to create the required aperture set by rotating the aperture ring on the lens or from the camera. The aperture rings are generally found on manual focus lenses. In autofocus cameras the aperture is controlled from the camera itself although it is a feature of the lens. All lenses have a minimum and a maximum aperture. The minimum aperture determines the maximum amount of light that can enter the camera. Sometimes the aperture is also Apert rture remadeby denoted as 1:4 1:4 or or 1:5.6 1:5.6 instead of just f/4 f/4 or f/5.6 f/5.6.. Why is that? It is because the aperture is also a ratio of the thebla lades ambient light with the light entering the camera. Thus an th aperture of 4 or f/4 also means that only 1/4 of the Apert rtureblades ambient light is falling on the film.
Page 9 of 25
11/6/2007
Understanding f values Each aperture setting, say f/8 is called One Stop Stop in photographic terms (just like shutter speed). What we have to know is that a change of aperture from one stop to another stop, i.e. change in one stop, will reduce/increase the light by a factor of 2. Hence a change from f/5.6 to f/4 will give u double the light whereas changing from f/5.6 to f/8 will giev you half the light at f/5.6. Here we are assuming that shutter speed is kept constant throughout. Let us look at why we have such odd values to represent the aperture values. Why do we have f/16, f/11? For understanding this we shall take a few pages out of our school math’s book. At maximum aperture the aperture blades do not guard any part of the lens. Then the area of the 2 lens is, p r , considering that the radius of the aperture is “r”. Now the aperture is changed by 1 stop. So the light will be halved. For letting in half the light that was entering previously the area of the aperture will be halved. If the radius is now R, then the area will be p ´
r
2
p ´ R
2
=
2 1
Þ
r R
=
2 = 1.41
p R
2
. So we know that,
Hence we see that the ratio of the radii is of the order of
1.41. So with a reducing aperture the radius decreases by 1.41 times. The f-number is the number of times the radius has decreased (number of f-stops on the lens) multiplied with the minimum aperture and 2 . So if the minimum aperture of a lens is 2.8 and the number of f-stops is 6 then the aperture range is 2.8, 4, 5.6, 8, 11, 16.
Angle of view In photography, angle of view describes the angular extent of a given scene that is imaged by a camera. It parallels, and may be used interchangeably with, the more general visual term field of view. The angle of view of a camera is a function of three parameters: · · ·
The dimensions of the film format or image sensor; The focal length of the photographic lens projecting the image; and The kind and degree of distortion of the lens.
The angle of view for a 50mm lens with 35mm film has an angle of view of ~ 43°
Page 10 of 25
11/6/2007
Lens Types and effects Lenses are often referred to by terms that express their angle of view: Ultra wide-angle lenses, also known as fisheye lenses, cover up to 180° (or even wider in special cases) · Wide-angle lenses generally cover between 100° and 60° · Normal, or Standa Standard rd lenses generally cover between 50° and 25° · Telephoto lenses generally cover between 15° and 10° · Super Telephoto lenses generally cover between 8° through through less less than 1° Zoom lenses are a special case wherein the focal length, and hence angle of view, of the lens can be altered mechanically without removing the lens from the camera. Longer lenses magnify the subject more, apparently compressing distance and (when focused on the foreground) blurring the background because of their shallower depth of field. Wider lenses tend to magnify distance between objects while allowing greater depth of field. Another result of using a wide angle lens is a greater apparent perspective distortion when the camera is not aligned perpendicularly to the subject: parallel lines converge at the same rate as with a normal lens, but converge more due to the wider total field. For example, buildings appear to be falling backwards much more severely when the camera is pointed upward from ground level than they would if photographed with a normal lens at the same distance from the subject, because more of the subject building is visible in the wide-angle shot. Because different lenses generally require a different camera–subject distance to preserve the size of a subject, changing the angle of view can indirectly distort perspective, changing the apparent relative size of the subject and foreground.
What is a Normal Lens? Lens? A normal lens is a lens which has an angle of view equal to the angle of vision of the human eye. For cameras which use 135 film the normal lens is 50mm. This value depends on the film that is used by a camera. Why? Because the formula is, 2
2
Focal length of a normal lens = Ö (length of film + breadth of film )
Since the viewable area on film (negative size) is 24 X 36 mm, the length becomes 43.5mm. This is taken to be 50mm. Actually a range of focal length is taken for normal lens. 45-55mm lenses are taken to be normal. Any focal length below 35mm is wide angle and above 80mm is telephoto. Any lens which has variable focal length is called a zoom lens. A COMMON MISCONCEPTION PEOPLE HAVE IS THAT ZOOM LENSES ARE TELEPHOTO LENSES AS THESE LENSES ARE IN THE TELEPHOTO RANGE. ZOOM LENSES NEED NOT BE TELEPHOTO LENSES. LENSES. There can be wideangle zoom lenses, e.g. 19mm – 35mm.
Page 11 of 25
11/6/2007
Below: An example of how lens choice affects angle of view. The photos below were taken by a 35 mm camera at a constant distance from the subject. Notice how the angle of view changes with change in focal length of the lens lens
Figure i - 28 mm lens
Figure ii - 50 mm lens
Figure iii - 70 mm lens
Figure iv - 210 mm lens
Page 12 of 25
11/6/2007
·
F i lm typ type es
Film consists of a thin Silver Bromide coating on a strong base of gelatin (colourless). The gelatine has no function other than holding the silver bromide coating. Silver bromide is sensitive to light. So when light falls on the film the compound breaks into silver and bromine. The silver is deposited on the film base and the bromine is released as gas. Thus the latent image is formed. A picture consists of light and dark parts of varying intensity. The parts where bright light falls cause rigorous reaction on the frame and so more silver is deposited and those parts of the frame, frame, which do not receive any light, does not deposit any silver. So you see that the whole reaction depends on the intensity of light. So parts where reaction takes place also can also have some unreacted silver bromide left. Once the film is developed in a lab the unreacted silver bromide is washed off and only the silver remains on the film base. Thus the negative is made. This is the scenario for Black&White film. For Colour Silver brom idecoating film there are 3 layers of silver deposit. One layer for receiving the colour red, one for blue and one for Filmbase green. Any colour is a combination of these 3 colours. So cyan light will deposit silver in both blue and yellow because it is a combination of both these colours. Blue ellayer
Green enllayer Redl edlayer Filmbase
What is a frame? A frame is a picture on the roll of film. When we refer to each picture on a negative we are actually referring to each frame on the negative.
So the first category of film is whether it is Black&White (B&W) or Colour. There is a subcategory within this. That is the film speed. Film speed is denoted as ASA, ISO and DIN. ASA ® American Standards Association ISO ® International Standard organization DIN is some German standard, but the full form is unknown to me. This is now obsolete. ASA and ISO have the same values. Film speed ranges from ISO(or ASA) 25 to ISO 6000. Generally we get ISO 100, 200 and convey? ISO/ASA values give you an idea about how 400 in the shops. What do these values convey? sensitive the film is to light. Higher the value, more sensitive is the film. The sensitivity of the films is relative. relative. No absolute value is ever used. For example, an ISO 200 film is twice as sensitive as a ISO 100 film and half as sensitive to light as ISO 400 film. That means if we use a film with high ISO value, it would require less amount of light. What it means to a photographer is that he can use a higher shutter speed and/or lower aperture (higher f value) than what he would have used if he had used a lower ISO film. This is shown in the chart below, Combination table table So it seems that using a film with higher ISO value is always better as it allows us to use a larger range of shutter speed and aperture in general light. True, but it also has a disadvantage. Faster films films (films with high ISO values) tend to have larger grain, especially in B&W films. What is is grain grain? ? If you look closely at pictures on old newspapers then you’ll see that the pictures are actually created by groups of dots. These are generally not visible except in large sized prints prints (photos) and the film used was fast, i.e., ISO 400 or more.
Note: There are other categories also. B&W films can be panchromatic Note: panchromatic or orthochromatic. Colour films can be compensated for daylight or for tugnsten orthochromatic. light. The films that we normally use are daylight compensated. So you must think carefully before selecting your film. Think of where you are going to shoot. Think of the light condition at your shooting area, if you have a tripod or not, if you are going to make large prints, if you actually want grains on your shots or not (sometimes photographers prefer grains on their prints for special effects).
Page 13 of 25
11/6/2007
·
E xpo xposure sure
Each photograph is taken by a combination of shutter speed and aperture. Film speed is constant for a particular film. So once that film is loaded the speed is set automatically by autofocus SLRs (though it can be changed manually) and set manually for manual SLRs. Aperture and shutter speed has to be set together to get a photograph. One cannot go without the other. The combination of shutter speed and aperture allow a certain amount of light which is always constant for that combination. This is called exposure. exposure. Suppose we use f/5.6 at 60. This will allow the same amount of light for every camera, lens or anything that you change. Now suppose that a particular photograph was taken with f/5.6 and 60 then we could achieve the same result by changing shutter speed to 30 (this allows double the light than 60, Refer to Shutter speed range range)) and f/8 (this allows half the light than f/5.6, Refer to Aperture range range). ). Thus the same amount of light is allowed as in the previous case. So, if a photo was taken at f5.6 and shutter speed of 60 with ISO 200 film, then it can be taken at f/8, shutter speed 60 with ISO 400 film. This is the most important aspect of photography. Check the table below to see how all the parameters can be interchanged to give you the same photo. Row 1 shows the original configuration. Row 2 to 5 shows how the same photo Combination table can be taken by varying varying shutter shutter speed Serial Shutter Aperture ISO and aperture for ISO 200. Row 6,7 is speed the configuration for the same picture 1 60 5.6 200 using ISO 100 film (once shutter speed 2 3 4 5 6 7 8 9
30 125 500 15 60 30 125 60
8 4 2.8 11 4 5.6 5.6 8
200 200 200 200 100 100 400 400
is changed and once aperture). The same thing is shown in Row 8,9 with ISO 400 film. From the chart we can conclude that if aperture is increased by n stops then shutter speed has to decreased by n stops to get the original picture and vice versa.
Here we get a clear picture about the relationship between shutter speed and aperture for a fixed film speed. Film speed is never changed because it is constant for a particular film. The values are given in the chart for giving you an idea of what the shutter speed and aperture will be for different film speed. We should choose the film that we need accordingly. Why should we vary shutter speed and aperture once we have a particular combination? The camera makes a suggestion about the shutter speed and the aperture, refer combination? t o Metering Metering chapter. This value might have to be changed for our needs. For instance For capturing a fast moving object we need a high shutter speed and a low aperture. Once we get the suggestion from the camera then we’ll know just how much to change. For example when the camera suggests f/11 at 250 on a bright day. If we need to capture the photo of a fast moving car we need a shutter speed of 500, say. Then we’ll change the setting to f/8 at 500. We refer to the suggestion made and we see that the required shutter speed is one stop more and hence the required aperture would be 1 stop less.
Never change the film speed when the film is loaded. loaded . Only set the speed when the film is loaded if the camera does not set the film speed automatically. Cameras set this automatically by the DX coding coding on on the film canister when the film is placed inside. If the film speed is changed then you will get consistent underexposed underexposed or overexposed pictures depending upon the change. overexposed pictures
Page 14 of 25
11/6/2007
·
Me M eter ing
Every camera has an inbuilt meter to measure light and accurately decide which combination of shutter speed and aperture is to be used in any condition. The autofocus cameras make their decision based on the mode mode set by the photographers. Almost all autofocus cameras have 4 modes P, S, A, M. P Program mode The modes are explained in detail later in the book. S Shutter priority mode Modes Refer to Modes A Aperture priority mode M Manual mode Manual cameras have no modes built in. When we look through the camera and half press the shutter, we get all kinds of information (depending on the camera), like shutter speed and aperture. The camera based on its light meter gives these values. When you press the shutter release button the camera will take the photograph with the shutter speed and aperture displayed in the viewfinder. Since we get the values when we look through the camera, this kind of metering is called TTL metering metering.. TTL stands for Through The Lens. There is another kind of metering called Off Camera metering. This is done by specialized meters, which are bought separately. We shall not deal with those in this book. Instead we shall look closely at TTL metering which is found all cameras. TTL metering is of 3 types. Centre weighted meterin terin area · Centre weighted When you like look through the viewfinder you will see something in fig. A. It means that the meter will give 30% weightage to the area within the larger circle and 70% weightage to the area of the rectangle outside the large circle. This 30-70 ratio is not fixed and varies from camera to camera. It can be 25-75, 35-65 or even 40-60. This kind of metering is found even in the old cameras. This metering is useful for general photographs where the subject is in the centre or the subject is covering a large part of the frame.
·
Fig.A
Spotmetering Spot metering is not used in general photography. It is used only in special conditions. When Spot Metering is being used, the small inner circle in the viewfinder is the only sensitive part. The camera gives 95% weightage to Spot meteri ringz gzone this area and only 5% weightage to the rest of the view finder. It is very useful in conditions where there is a very large variation of light throughout the frame whereas the subject maybe quite small or a part of the subject has to be correctly exposed. In such a case spot metering is used. Through the view finder the small circle has to be Fig. B placed on the subject or the part of the subject, which has to be correctly exposed, and then the shutter should be half clicked to activate the meter. Spot meter is less sensitive to light than centre weighted meter. There maybe cases where spot meter is unable to give you a exposure due to bad light but centre weighted meter can. can. All cameras do not have a spot meter. Medium range to upper range cameras have this kind of metering.
Page 15 of 25
11/6/2007
Important note: note: Film cannot take too much variation in light. If a scene has a large variation of light, from very dark to very light, films cannot record every part of the scene perfectly exposed. For instance, a scene where bright daylight and shadow will not show both light and shade properly illuminated. Either shadow has to be properly illuminated with the lighted parts very bright or the lighted parts properly illuminated and shadow parts quite dark. It has to be decided by the photographer and the meter has to be focussed on that part of the scene for the correct exposure.
·
Evaluative metering This kind of metering is present only in autofocus cameras. The frame is divided into multiple regions which varies from camera to camera. The camera gives a weightage to each zone and calculates the shutter speed and aperture accordingly. Different manufacturers name this light meter in various ways. Nikon uses 3D Matrix metering, CANON uses Evaluative metering, Minolta uses Honeycomb pattern metering. All these are customized forms of evuluative metering.
Meteri eterin ng zones
Fig. C
The only difference with the previous meters is that you will not be able to see the different zones through your viewfinder as in the case of spot meter or centre-weighted meter. This meter is good for almost all kinds of scenes.
Exposure Compensation Although the TTL meters are very advanced, they fail in certain conditions, in c onditions where there is too much light and where there is very little light. In both cases, cases the meters fail to give proper exposure. What do you do in such cases? Yeah, we all depend on the meter to give us the correct exposure but if it fails then we’ll end up with very bad photo(s). First of all, how do we know if the meter is failing? OK, here’s how. Check if the subject is backlit backlit,, i.e. if the light source is behind the subject. Now light source does not necessarily mean that the light is directly behind the subject. If we want to take somebody’s photo in the shade with the sky as the background, backlit.. So in this case the camera the sky becomes brighter than your subject. Hence he/she is backlit will look at the whole scene and decide that there is a lot of light around and so it will be fooled into suggesting a lower exposure. exposure. The result? In the photo you will have a beautiful sky and a very dark, almost unrecognizable, person. Since there was so much light the camera was fooled into underexposing the subject, as the subject does not cover a very large area of the frame. Now how do you avoid this? First aim your camera at the sky and take its exposure reading. Then come close to your subject so that only he/she covers your frame. Take that exposure. Suppose, the exposure of the sky is f/11 at 500 and your subject is f/5.6 at 125. You see there is huge variation of 4 stops. One way is to set your camera to use only the subjects’ exposure, by manually changing in manual mode or by using the camera’s feature of exposure lock (this lock (this feature may not be present in all cameras. It primarily locks the exposure taken at a particular point and does not change even if the scene changes). Another way to do this is to compensate exposure. In such a case (where the difference is 4 stops) compensate compensate for for +2 stops. This way you will get a much better picture of your subject. Setting the camera to compensate is specific for a camera, so it is better to go through the camera manual. ± n
stops of compensation is also referred to as ± n EV. stops of EV. EV
Page 16 of 25
® Exposure
Value
11/6/2007
Similarly, in a dark condition where most of the frame is is dark and you have a well lighted but relatively small subject, compensate by a negative value as the camera will tend to overexpose the photo.
Exposure bracketing As in the previous example I had explained how the camera can be fooled and how you decide to compensate for exposure. Now there is a very simple catch to it. Supposing that the photo that to you areisgoing to take of great value photo. to you. In It such mightahappen that do thewe picture that you are going take a “once in a is lifetime chance” case what normally do? We take the same photo with +1EV, -1 EV and at normal exposure. That means taking 3 photos, one with 1 stop overexposure, one with 1 stop underexposure and one with the exposure suggested by the camera. So what happens is that if the camera had originally suggested an exposure that may be say, -1 EV of the perfect photograph, you will be capturing it by covering a wide range of exposure. This is called exposure bracketing. bracketing. Or if you want to be very particular, you can take 5 photographs, ± 2 stops. In some cameras this is an inbuilt feature. In those cameras only the EV has to be set and fired away. In cameras, which do not have this feature, the photographer has to manually change the exposure. If you are going to do this manually then changing shutter speed and/or aperture can vary the exposure. You have to decide on that.
Change shutter speed or aperture? Like we said before we can either change shutter speed and/or aperture. Now how do we decide which one to change? Here are a few guidelines to help you out. ·
Depth of field (DOF)
This something which could have been explained with just 2 photographs. Well, since I have to tell you everything in black and white, here goes. When you focus on an object through the lens, you are basically moving the lens up and down so that the image of the subject falls onto the film. So what you are doing while focusing, is that the lens moves a particular distance according to the distance of the subject from the camera. I n turn, the subject is focused focused on the film plane. Now what happens is that when the photo is taken, then some amount if distance in front of the subject as wells as some distance behind the subject is focused. Camera ra In the figure Y is the distance of between the Dis isttance ceof of camera and the first object in focus and Z is the distance subject ffrrom camera ra of the last object in focus. The difference of Z and Y is Subject the Depth of field (DOF). \Depth of field = Z – Y DOF depends on the distance of the subject from the camera, the aperture and the focal length of the lens. For a larger a DOF we go for a smaller aperture. DOF decreases with decrease in subject distance from Depthof ffield ield the camera and decreases with increase in focal length. length. For taking photographs of scenery we take shots at low aperture (f/11 or f/16) so that we get a very large DOF. For taking shots of scenery, the object is at infinity (with respect to the lens). For every lens there is a maximum distance upto which it needs focusing. After that point everything will be focused but the lens only needs to be set at infinity. Eg. A lens focuses upto a distance of 10m. For any subject beyond 10m the lens will be set at infinity.
Note: Using a very big aperture very close to the subject can give such a Note: small depth of field that the subject’s nose is focused whereas the ears are out of focus. This is sometimes wanted and sometimes not. When in doubt, use exposure bracketing or use DOF preview button if the camera has one.
Page 17 of 25
11/6/2007
While taking portrait photos we want a lower DOF so that disturbing elements behind the subject is off focus. At such a time we use the maximum aperture of the lens. That gives us the minimum DOF. Examples of depth of field
Picture shot with f/32. The background is sharp and crisp.
·
Pic Picture ture shot with f/5.6. The background is blurred.
Capturing a moving object
There are times when you want to photograph a moving car, a flying bird, or for that matter any moving object. The light conditions maybe good and so the camera might suggest a shutter speed of 250 at f/16. But this might not be enough for the subject. So you change it to 1000 at f/8. This is a case when the shutter speed needs to be changed. For a moving object the shutter speed Object has to be changed depending upon the relative speed of the object. For a moving object which needs a shutter speed of 250 at a distance of say, 10m from the subject, will need a much A higher shutter speed when the distance between the camera and the object is less than 10m. This is because the relative speed increases with B decrease in distance. Suppose we have an object moving along the arrow. We have 2 cameras, A and B, placed. Since A is closer to the line of movement of the object, the relative speed of the object will be more than B. Hence camera B will need a higher shutter speed than A. ·
Minimum handheld shutter speed
The minimum shutter speed handheld 60. the If the camera shutter gives aspeed shutter speed of less than 60 then tryfor changing thephotography exposure soisthat minimum is at least 60. If you cannot then you should use a tripod. This value of 60 is used because it is seen that most photographers can hold the camera steady at 60 and above. Below 60 there can be very minimal shake while the photograph is being taken. This may not show up on a small postcard size photograph, but will show up in a slightly bigger photo, 5” X 7” and bigger. As you have more and more experience and expertise, you will be able to take photographs with lesser shutter speed like, 30, 15 or even 8. But that will only come after quite a bit of expertise.
Page 18 of 25
11/6/2007
·
Using F la lash sh
Flash is a device that is used for providing light in those conditions where the ambient light is inadequate. A lot of autofocus SLR’s come with built in flashes. No manula cameras have built in flashes. But all cameras have a provision to attach an external flash on the camera. The point where the flash is connected on the camera is called a hot shoe. shoe. Flashlight is equivalent to sunlight. No no. I don’t mean that at night you should have photos, which look like those were shot during daytime. What I mean is that the colour of light chart ( this chart lists the emited by a flash is the same as sunlight. On the colour temperature chart temperature for all kinds of light) the light for sunlight is 6600 K (Kelvin). Flashlight has the same colour temperature. That is why when flash is used during the day, the light from the flash and sunlight mix very well. Hence using a flash during the day is a very good way of lighting the shadow areas. Flashgun? A flashgun is rated by the value of GUIDE NUMBER How do we rate a Flashgun? A (GN). It tells us how powerful a flashgun is. Guide number (GN) = Aperture X distance of subject. We know that the intensity of light decreases with increase in subject distance from the camera. So as the aperture is increased it allows more and more light on to the film. So now we know that when the distance increases then the aperture also has to increase. GN also has to be defined whether the value is in feet or in metres. For example, GN of a flash is expressed like this, 24 in metres at ISO 100. The equivalent GN of the flash in feet will be 78.74 in feet at ISO 100, as 1 m = 3.28 feet. Now suppose we are using a flash which has a guide number of 14 in metres at ISO 100. Now the distance of the subject from the camera is 2 m. At this distance, the aperture will be GN/distance, i.e. 14/2 = 7. We generally do not have a setting of f/7 as aperture. So, the next closest value will be f/8. So the aperture will be set to this. The film speed is also important. If the film in use is ISO 200, then the aperture will be halved. Here half the aperture means 7 X 2 = f/14. So the closest shutter speed will be f/16. Hence this aperture should be used. Thus we see that for more sensitive film the aperture reduces and so the depth of field field increases. Flashlight is visible upto the distance permissible by the largest aperture on the lens.. If the lens has f/4 as the largest aperture and the GN of the lens is 24 in metres at ISO 100 lens then, if you’re using ISO 100 film, then the maximum distance that the flashgun will cover is 24/4 = 6m. If you’re using ISO 200 film then the distance will be doubled. That is, 12m. So at ISO 200, the maximum distance that will be visible on film is 12m. I have seen people using flash for taking photographs of objects very far off, nearly 100m with tiny flashguns. This will never work because the flash does have enough power to illuminate something that far off.
Note: Never set the shutter speed above the flash synchronization speed Note: when using a flash.
In autofocus cameras, the shutter speed is normally set by the camera itself and so it never goes below the flash synchronisation speed. speed. But, if you are using a manual SLR or an autofocus camera in Shutter priority mode or in Manual mode then the shutter speed depends upon you. As discussed in the Shutter speed, we have seen that there is a maximum shutter speed for which the frame is completely open. Now what happens in flash photography is that the flash is light source that is triggered once the shutter release button is pressed. The flash emits th light for only 1/16000 of a second. Now the shutter speed is “x”. This light source can fire at anytime starting from 0 to 1/x seconds. So what we need is an open window to absorb all the light on the film. If the shutter speed is more than the synch speed then the frame is never completely open and so the shutter curtain will block the light coming on to the film. There are times when the photographer had forgotten to set the shutter speed on or below the synch speed and have got a picture that is half lighted.
Page 19 of 25
11/6/2007
Flash techniques There are quite a few techniques with flashguns. I do not intend to go through all of them but I will discuss one or two basic techniques here. 1. Fill flash A very basic mistake or thought that people have about flashguns is that they think flas hgun hguns s can be used only when it is dark. It is not so. Flash can and should be used in broad daylight. Yes, on a very sunny afternoon, if you take photographs of people you shall get ugly the eyes cameras, and nose the of the subject.isThis can be then avoided by using the shadows flash. Ononautofocus exposure set automatically so that the flash light as well as the sunlight mixes together as both sunlight and flash light have the same light temperature. 2. Bounce flash Sometimes, while shooting indoors with a flash we do not prefer the flashgun to fire directly at the subject. Instead, if the flash head is tilted upwardsand fired (provided there is a ceiling and the flash has a tiltable head) then the light is reflected from the ceiling on to the subject. The advantage in this case is that the surrounding area of the subject is also equally lighted and it gives a smooth effect. Remember to overexpose the photo by 1.5 stops at least, as the ceiling will absorb a lot of light and the light has to travel up towards the ceiling and then down to the subject. Also check that the ceiling is white coloured. If the ceiling is of a different colour, the subject will be illuminated by that light of the colour of the ceiling 3. Slow Flash synch This is a technique that is used mainly to get the ambient effect alongwith the flash effect. Suppose, in the evening, a man is standing in a park and behind him there are beautifully illuminated buildings. Normally, the man will be well lighted but his surroundings will be absolutely dark or faintly visible. This is because the background is far off and so the flashlight will not reach the buildings. To get the subject as well as the background what we should do is take the photograph with the flash and also reduce the shutter speed. First take the reading of the background with the aperture set to what it should be after calculating from the subject distance and the GN. With that aperture and shutter speed take the photograph of the subject. Slow and night photography is a big field. This was just an introduction into this aspect of photography. There is a group of flashguns called dedicated flashguns flashguns.. These flashguns can give a properly lighted photo with any shutter speed. Actually dedicated flashguns can work with certain cameras. For instance CANON manufactures dedicated flashguns only for CANON cameras, Nikon, Minolta and a whole lot of other manufacturers do the same for their products. What happens with these flashguns is that once the shutter release button is pressed the flash starts firing for sometime. So there is no need of setting the shutter speed to the synch speed or below. These flashguns have other features like flash autozoom. Actually these flashguns communicate with the camera and so when the lens zooms the flash head also zooms. Flashes also have an angle of light spread. Just like lenses have a viewable angle, angle, flashes have a similar angle. So while zooming the flash head manually remember that the angle of light is equal or more than the lens angle of view. For all flashguns with zooming heads there is a scale on the head, which shows the angle of light equated to the lens focal length. This value is given in mm, i.e. equivalent to the lens focal length. Set this value equal to the focal length of the lens in use. Suppose if the flash head is set to 35mm and the focal length of the lens is 28mm then the edges of the photo will appear dark.
Page 20 of 25
11/6/2007
Digital Photography Digital photography today has taken over the world. 35 mm photography is now a dying art. This does not mean that the concepts of photography have changed. The concepts that we have discussed before remains the same. The most important change is that the films used in 35mm cameras have been replaced by memory cards. Unlike photographic films digital memory cards can be used over and over again. I have listed the differences between film cameras and digital cameras here Capture medium Capture format Processing
Film camera Orthochromatic or panchromatic films used Film format (120, 135, 5 X 4, 10 X 8) Film converted processed to negative and then negative is processed to produce prints
Digital camera CCD or CMOS chips pixel count, digital file type (RAW, TIFF, JPEG) Image is captured on memory card, from which images can be printed
CCD CCD stands for Charge Coupled Devices. It is a chip which converts light into electricity. This chip is used to draw the image from the light which falls on to it. Digital color cameras generally use a Bayer mask over the CCD. Each square of four pixels has one filtered red, one blue, and two green (the human eye is more sensitive to green than either red or blue). The result of this is that luminance information is collected at every pixel, but the color resolution is lower than the luminance resolution. Better color separation can be reached by three-CCD devices (3CCD) and a dichroic beam splitter prism that splits the image into red, green and blue components. Each of the three CCDs is arranged to respond to a particular color. Some semi-professional digital video camcorders (and most professionals) use this technique. Another advantage of 3CCD over a Bayer mask device is higher quantum efficiency (and therefore higher light sensitivity for a given aperture size). This is because in a 3CCD device most of the light entering the aperture is captured by a sensor, while a Bayer mask absorbs a high proportion (about 2/3) of the light falling on each CCD pixel. Since a very-high-resolution CCD chip is very expensive as of 2005, a 3CCD highresolution still camera would be beyond rangethat even of amany professional photographers. There are some high-endthe stillprice cameras use rotating color filter to achieve both color-fidelity and high-resolution. These multi-shot cameras are rare and can only photograph objects that are not moving.
P ix el count A digital photograph or digital image is made up of a number of dots placed horizontally and vertically in a matrix across the entire frame. These dots are technically called pixels. pixels. Th The e number of pixels n for a given maximum resolution (w horizontal pixels by h vertical pixels) can be found using the formula: n = wh. This yields e. g. 1.92 megapixels (= 1,920,000 pixels) for an image of 1600 x 1200. The majority of compact (not SLR) digital cameras have a 4:3 aspect ratio, i.e. width/height = 4/3.
Page 21 of 25
11/6/2007
Resolution Resolution provides an indication of the amount of detail that is captured, but, like the other metrics, resolution is just another factor out of many in determining the quality of an image. Furthermore, different methods of creating an image make it impossible to compare the resolutions of cameras simply based on the number of pixels produced by the image sensor. Another factor to be taken into consideration is that the relative increase in detail resulting from an increase in resolution has to be judged based on the square roots of the resolutions. For example, increasing resolution from 8 megapixels to 10 megapixels does not give an increase in perceived detail of 25% as one might expect. Instead, compare the square root of 10 (3.16) with the square root of 8 (2.83), and you can determine that the increase in perceived resolution is only 12%, which is fairly difficult to see.
S ens or s i ze a and nd a ang ng le of vi view ew
Cameras with digital sensors that are smaller than the typical 35mm film size will have a smaller field or angle of view when used with a lens of the same focal length. This is because angle of view is a function of both focal length and the sensor or film size used. If a sensor smaller than the full-frame 35mm film format is used, such as the use of APSC-sized digital sensors in DSLRs, then the field of view is cropped by the sensor to smaller than the 35mm full-frame format's field of view. This narrowing of the field of view is often described in terms of a focal length multliplier or crop factor, a factor by which a longer focal length lens would be needed to get the same field of view on a full-frame camera. If the digital sensor has approximately the same resolution (effective pixels per unit area) as the 35mm film surface (24 x 36 mm), then the result is similar to taking the image from the film camera and cutting it down (cropping) to the size of the sensor. For an APS-C size sensor, this would be a reduction to approximately the center 50% of the image. The cheaper, non-SLR models of digital cameras typically use much smaller sensor sizes and the reduction would be greater. If the digital sensor has a higher or lower density of pixels per unit area than the film equivalent, then the amount of information captured will differ correspondingly. While resolution
Page 22 of 25
11/6/2007
can be estimated in pixels per unit area, the comparison is complex since most types of digital sensor record only a single colour at each pixel location, and different types of film will have different effective resolutions. There are various trade-offs involved, since larger sensors are more expensive to manufacture and require larger lenses, while sensors with higher numbers of pixels per unit area are likely to suffer higher noise levels. For these reasons, it is possible to obtain cheap digital cameras with sensor sizes much smaller than 35mm film, but with high pixel counts, counts, that can still produce high-resolution images. Such cameras are usually supplied with lenses that would be classed as extremely wide angle on a 35mm camera, and which can also be smaller size and less expensive, since there is a smaller sensor to illuminate. For example, a camera with a 1/1.8" sensor has a 5.0x field of view crop, and so a hypothetical 5-50mm zoom lens will produce images that look similar (again the differences mentioned above are important) to those produced by a 35mm film camera with a 25– 250mm lens, while being much more compact than such a lens for a 35mm camera since the imaging circle is much smaller.
Page 23 of 25
11/6/2007
P oint ointss to llook ook a att w while hile buying a S LR Cost Yeah. We cannot go beyond what we have in our pockets.
B od ody y This is a very important because this is what you are going to hold in your hand. It has to be comfortable in your palm. Check for the weight of the camera. It should not be too heavy for you. Although heavy cameras are good as they have extra protection for the interior of the camera, it should not be too much for you. You will see that all Nikon cameras are heavier than their counterparts. Be it, Canon, Minolta and several others. This is because Nikon cameras generally have a metal covering underneath the polymer cover. Check with the dealer about the camera body or on the Internet or on leaflets about the camera. Depending on your usage decide on the camera. If you would like to use your camera like a pro then you would want to go for a camera with a sturdy body, which can take a few knocks, be somewhat dust resistant.
Mod Mo des Almost every autofocus SLR manufactured today comes with the 4 standard modes, PSAM. mode setting gives total control camera. Thelight camera decidesand on the the PSAM. Program exposure based on the (P) certain program selected by to thethe photographer, conditions library of similar photographs in its memory. Program mode can be of various types, Portrait, Landscape, Macro, Night, High speed. All these program modes are for preset conditions. For instance in Portrait mode the camera will use the largest aperture for getting the minimum depth of field. In Landscape mode the camera will select an optimum aperture for getting maximum depth of field. The mode descriptions are given in the camera manual. Shutter priority mode (S) will allow the photographer to choose a shutter speed and once the shutter speed is chosen the camera will decide on the aperture to be used. Aperture priority mode (A) is similar to the shutter priority mode. Only difference being that the aperture is set by the photographer while the shutter speed is decided by the camera. Manual mode (M) gives full control to the photographer. With this setting the photographer sets the aperture and shutter speed manually. The camera tells the photographer whether the particular combination of aperture and shutter speed is under or over exposed. The camera is fully overridden by the photographer in this case.
Mete Met er ing modes In all autofocus SLR cameras we find Centre weighted and Matrix metering (or its equivalent). Only on medium to high-end cameras will we find Spot metering. This is not absolutely necessary. Although it is definitely a bonus and at times it does help a lot. Spot metering is used about 5-10% photographs.
F lash mo mode dess Flash modes are available only from medium range SLR’s. Those cameras can alter the flash output power, allow slow flash synch synch,, rear curtain synch. These modes are quite important while shooting with the built in flash. Dedicated flashes have these features built in and can be rd controlled from the camera settings, but these features cannot be used by all 3 party manufactured flash. These features are also a bonus and not absolutely necessary. These features will be used about 40-50% in flash photography.
Page 24 of 25
11/6/2007
Mi sce scella llano nous us modes These modes are found in medium to high-end cameras. All these features are quite helpful though. · Depth of field preview. This button allows the photographer to view the depth of field at the aperture set. Normally when we look through the camera, the lens is kept at maximum aperture. This is done to allow the maximum amount of light through the lens for the best possible view. So if the maximum aperture of the lens is f/4 and the aperture set for the photograph is f/8 then the depth of field can be checked by using the DOF button. What happens then, is that the aperture is actually set to that aperture and so the DOF can be seen. ·
Multiple exposure mode This feature allows the photographer to take more than one shot on a single frame.
I hope this document has given you an insight into photography and it has instilled enough interest in you to take your knowledge further. I might have missed something in the document or there might be something you would like to point out. I would be very happy to receive your feedback, [email protected] or comments and/or queries at [email protected] [email protected] [email protected]
Page 25 of 25
11/6/2007
