Discover Photography

Focus-Exposure Lock

2008-06-15T19:18:00.007+05:30

Before I start off, let me tell you that this is one of the things that I find very irritating when a friends says that he/she doesn't know what it is and how to use it. Come on, if you call yourself a photographer or are even trying to be a decent photographer, then you ought to know how to use this feature of the camera.

What it is
So... focus-lock is also referred to as half-press, exposure-lock and so on. In most of the cases, unless your camera has a dedicated button for focus-lock or exposure-lock, this button is the shutter press button. Or, in other words, the same button that you click to take your photographs. Let us call this button the shutter-release from now on so that we have a consistent naming convention across this post.

The feel of this button
Now this is what it is. Unless you have a really cheap or feature-less camera then your shutter-release will have two steps of clicks as you press it. Most importantly you have to realize the feel of this button before knowing what it does. Unless you are able to press it correctly, there is no point knowing what is its use. So pick up your camera and bring it to the computer. There is no need of switching it on as this is a mechanical button and will work the same whether your camera is on or off. If your camera is really old and you have been monstering your way through that button, then it might have become soft and you wont realize the feel, and it might well be harder for you. I have seen this happen in only one camera till now - a friends Sony DSC-H1, where after less than a years use the button lost its half-press sensitivity and the functionality was totally lost.

So, now that you have your camera with you, take position and press the shutter. Give a slow/soft/slight pressure with your finger(I do hope you use your index finger to click. You can use other fingers of course, but the index finger is most responsive to touch/pressure and you are most likely to find the half-press point with this finger) and push the shutter down. Some cameras might have a hard shutter and this might need a harder push with your finger. Nevertheless, keep a constant pressure on the shutter and maintain that pressure as you push the shutter down. Feel the shutter as you push it down. At one point the shutter will stop and you will feel as if it has been pressed down fully. Of course, if it is your first time then you might well have pushed it all the way down. ;)

Keep trying this till you get that mild jerk/feedback as you slowly(really sl-o-o-o-w) push the shutter-release down. You will know that you have reached the half-press point if you get the feedback but you can still press the button all the way down. That is exactly what this half-press button is. If you press it half-way(till the click or feedback point) it does some functionality without taking the photo and if you push it all the way down, then it actually takes the photo. Try this again and again till you are able to get the half-press point every time. Increase the speed of the shutter-release, by giving more pressure each time, till you get really comfortable with this process.

Seeing it in action
OK, its great that you were able to find the 'sweet spot' on the shutter-release. Now the interesting part. You actually have to hold it at that point for about half a second to one second. Again this duration is dependent on the camera. If you press it completely by mistake or release it a little bit then the effect, and effort, is lost. Let us now see this feature working so that you know whether you are holding it at the spot correctly or are releasing it prematurely.

So switch on your digital cameras and keep it in the shooting mode, ready to take pictures. You will see a small square in the center of your LCD screen. This is how it is in most of the point-and-shoot cameras. In case of other more advanced cameras, when you look through your viewfinder(Optical or EVF depending on whether you are using an SLR or an ultra zoom camera) or the LCD screen, you will see a square, multiple squares, a dot, or small squares/rectangles with dots or cross-hairs in them. Whatever it is, these are the focusing points on your camera.

Now when you half-press the shutter-release button, while attempting to shoot an image, you will notice one or many of the following things.
1) The focusing point(square or cross-hair, or dot) changes color or flickers with a different color. i.e in some cases the square turns red, in some cases the dot within the square turns red and so on. You will notice a marked change in the focus indicator.
2) There is a green/red circular spot that appears on the screen. Mostly in the top area.
3) The screen flickers and shows an exposure change. An exposure change means the image on the screen becomes brighter or darker or just flickers.
4) The image blurs and then becomes sharp again. This indicates that the camera is focusing.

This is the half-press point. To confirm that you are pressing it correctly, you can check that the indications mentioned above happen just once. Once the indication happens, it continues to remain that way on the screen, i.e screen doesn't keep flickering, the green spot stays continuously on the screen and so on.

If you release the shutter-release button then the indication disappears or if you press it completely by mistake then the photo gets taken. Try holding it at this point for a few seconds so that you are comfortable with the amount of pressure to keep on the button. Once you are comfortable holding it at this point for long time, depress it completely. You will find that the image is taken. Try to take the image as you would do normally - completely pressing the button at once and notice the behaviour of the camera. Then try to hold at half-press point for 2 seconds and then take the image and notice the behaviour of the camera. Try and compare these two ways to take a photo and note down the differences and try to find out what is happening.

In the next post we will take a detailed look at what functionality this offers and how it will improve your photo taking skills.

Metering

2008-04-12T17:44:00.004+05:30

I am continuing my blogs on photography after a very long break and this time I will talk about another one of the important terms that define a photograph. The term is called metering.

Metering is the way the camera judges the brightness or darkness of the image. When the camera sensor looks at an image, it had to judge how bright the image has to be before attempting to capture it. Another term for this is exposure, as we had seen previously. If you have an image or a scene that is mainly white but has a small dark coloured object of interest in the center, then it is very likely that you will miss the object or you will not see the finer details of that dark object. In the case of a camera, the camera has metered the images for the bright areas and hence loses the details of the dark object. Similarly, if you have a predominantly dark image, such as in a dark room, and a small bright object, such as a bulb, then the camera will meter for the dark areas and the bright object will look washed out or over exposed.

You can understand this by relating to your own experiences in photography. Have you ever tried to take a photograph of the moon on a dark night with a simple point-and-shoot camera without a huge zoom? You would have probably noticed that the moon would appear totally white against the black background and you would have lost all the details on the moon, such as the craters. This is because the image is predominantly dark and the camera processor has been trying to take the photo as brightly as possible and in the process made the bright object even brighter and has hence overexposed it.

You can also imagine how the brain does this metering. Suppose you enter a dark tunnel in a fast moving vehicle. A fast moving vehicle because you don't want to give your brain enough time to adjust gradually, like when you are walking into the tunnel. So, when you enter the tunnel, everything goes dark and you are not able to see anything. This also happens when you walk into a room at night and switch off all light. For an instant you cannot see anything and all goes pitch dark. Slowly, your eyes adjust to the situation as the brain begins to meter the scene for darkness and you are able to see/identify the presence of objects in the dark. In case of the eyes, it more to do with adjusting exposure than metering, as the pupil dilates and allows more light to enter, but there is still a hint of metering here also. A reverse thing happens when you enter from dark into bright light. For an instant, everything appears white till the brain and eye slowly adjust to the new scene and adjust the exposure and metering apropriately.

The metering on the camera is far far more complex than just adjusting to dark and bright scenes and this is beauty of cameras. You can ask the camera to meter to a particular point of interest in the scene before taking the photograph. There are 3 main types of metering - Average or Evaluative metering, Center-weighted metering, Center or Spot metering. The actual names of these metering would be different on different cameras, but the meaning would be very much similar.

Evaluative Metering meters for the entire frame and decides on an exposure that will try to show as much of the image with correct exposure as possible. This is generally recommended for images of landscape and sceneries and scenes.

Center-weighted Metering is similar to the Evaluative Metering but with the exception that it emphasizes the center area a little more. What this means is that it tries to get the area in the center as correctly exposed as possible even though it may be at the cost of the rest of the image. Although the rest of the image will no suffer too much since it is evaluative metering only. Its just that there is extra weightage on the center area.

Spot-Metering is a more specific form of metering where only the center 10%-15% is metered for exposure. This is used in cases where the entire image frame has a wide contrast/brightness range, but you as a photographer want only the center part of the image with the best exposure. Its not that only the center area is exposed correctly, but the entire image is exposed in such a way that the center area is expose correctly. This could mean that the surrounding areas are exposed correctly or is over/under exposed depending on the contrast/brightness details on the image. Spot meter is the most commonly used form of metering during bird photography and other forms of long distance wildlife photography where is subject is there in the center of the image.

Megapixels

2007-11-05T09:17:00.000+05:30

You would have heard a lot of people talking about mega pixels whenever it comes to camera. Whenever it comes to comparing cameras, the first question that someone asks me is "How many mega pixels does that camera have?". In fact I think that is one of the most uneducated question that someone can ask about cameras. Putting it simply, mega pixels don't make a camera. Now lets see what exactly it is.

First let us see what is a pixel.
Pixel stands for Picture Element (pics = pix). A pixel is like a single dot in the image. The image is composed of lots and lots of pixels. Each pixel is of a specific color. Assume that an image has pixels of a single color - red, the entire image will be red in colour. This way in a photo, there are multiple pixels each with a different color and hence a nice colorful image is formed.

A picture is measured in terms of its resolution. The resolution gives the number of pixels horizontally and vertically. So a picture of resuolution 640x480 has 640 pixels horizontally and 480 pixels vertically. Now let us see how many pixels are there totally in the image.

Total pixels-> 640 x 480 = 307200 pixels.

Consider an image of size 1280x1024..
Total pixels -> 1280 x 1024 = 1310720 pixels.

Lets write this in tens, thousands and millions.
1310720 => 1,310,6720 pixels. This is almost equal to 1.3 million pixels.
So, a camera capable of taking images at 1.3 megapixels can take images of resolution 1280 x 1024. Similarly a 5MP camera can take images of resolution 2592 x 1944. This is the basis of megapixels.

Also, in many cameras you will find something called Total Megapixels and Effective Megapixels. The total megapixels is the number of pixel sensing elements in the sensor of the camera whereas the effective megapixels will translate into the size of the image. The reason for this difference lies in the way the sensor is built. In conventional sensors, there are a fixed number of sensors for measuring red, green and blue and this is then processed into the resultant image. As a rule of thumb, if you see 2 different megapixel ratings for a camera, the one that you are concerned about is the smaller number. We will get into details of sensor construction later.

Shutter/Aperture Priority

2007-10-24T16:18:00.000+05:30

Some cameras have modes called shutter priority and aperture priority. These are not available in the basic point-and-shoot models but in some of the more advanced models. These modes are usually represented in the mode dial by S or Tv for shutter priority and A or Av depending on the manufacturers wish.

Shutter and Aperture priority modes are a sort of semi-automatic modes. In the fully-automatic mode, the camera will choose the shutter speed and the aperture value automatically depending on the exposure. These automatically chosen values cannot be changed or can be modified using a 'program-shift' feature that some cameras provide.

But now, in these modes, you have the option of choosing the shutter speed or the aperture value on your own and the camera will adjust the other parameter depending on the light and required exposure. For example, suppose the automatic setting requires an aperture of F/5.0 and shutter speed of 1/200s. Now, in the aperture priority mode, I set the aperture to F/2.8. Now the amount of light has increased because of the wider aperture. So correspondingly the shutter speed will be decreased to about, say 1/500s, by the camera, since it is in the aperture priority mode.

Similarly in the shutter priority mode, you are allowed to change the shutter speed value and the camera automatically chooses the best aperture value for a good exposure.

This might not sound very interesting during normal photography, but it makes for very simple shooting when shooting some creative photos.

Focal Length and Angle of View

2007-10-18T21:16:00.000+05:30

The last time we had a look at the picture to the left, we learned how to read the aperture specification from how it is mentioned on the lens. As you would remember, there is also another set of numbers on the lens. This represents the focal length of the lens. In this case the figures say 5.8 - 17.4, the readings being in mm.

The layman can translate this directly to the amount of zoom that the camera provides in terms of magnification(2x, 3x etc). The figures indicate that the cameras can zoom from a minimum focal length of 5.8mm to a maximum focal length of 17.4mm. So the magnification that the lens provides is 17.4/5.8 = 3x. This again reflects what is mentioned in the specification of the camera.

Now that we understand the significance of the figures mentioned, we can have a look at what the numbers exactly mean. For this we have to understand what is focal length. Without being too bookish, the focal length is the distance from the lens to the focus of the lens. The focus of the lens is the single point where the light converges after refracting from the surface of the lens. In the case of a fixed lens, this focus point is constant and is determined during the manufacture of the lens and depends on the curvature of the lens. You can read more about focal length and focus from these links - Focal Length and Focus.

Now lets move away from the geometrics and optics and focus on what it means for us as a photographer. As mentioned earlier, each lens has a fixed focal length and this cannot be changed. But cameras have a range of focal lengths as mentioned in the specification. This is achieved by using a combination of lenses. By using multiple lenses, in a straight line, and varying the distance between each of them, one can achieve different focal lengths.

Now most of the focal lengths are compared using the 35mm equivalents. The 35mm film was the most popular film format available and hence all focal lengths are translated into their respective 35mm equivalents. This is because digital cameras have varying sizes of sensors and there has to be a standard for comparisons. In case of compact cameras, the 35mm equivalent focal lengths are mentioned in the cameras specifications and in the case of SLR cameras a focal length multiplier is mentioned. In the case of the W80, the 35mm equivalent focal lengths for 5.8 - 17.4mm are specified as 35mm - 105mm. What this means in other words is that the 5.8mm lens on the W80 provides the zoom equivalent to a 35mm lens on a film camera.

We will take a more detailed look at what this 35mm equivalent means in a later post.

ISO - Light Sensitivity

2007-10-17T16:16:00.003+05:30

ISO adds another parameter to the Exposure equation. Till now we had established the relationship of exposure to aperture and shutter speed. From now on we will understand that Exposure is directly proportional to the ISO setting.

ISO is a measurement of the light sensitivity of the camera. Earlier we used to get films with various ISO ratings. A film with a higher ISO is more sensitive to light and on simple point-and-shoot cameras, a high ISO film would be more suitable to shooting in low light than a film with a lower ISO. In essence, that is what a high ISO will help you do - help you shoot in low light.

ISO might sound useful, but, on digital cameras, shooting at high ISO leads to an increase amount of noise in the photo. Noise is nothing but the graininess that creeps into images when you shoot at a high ISO. The noise happens due to various causes, the main reason being the over-heating of the sensing elements in the sensor of the camera. Putting it simply, to increase the light sensitivity of the sensor, more current is applied through the sensing elements. Because of this, the sensory elements are over heated and hence the resulting noise in the final images. Hence high ISO is not all that good for low light photography.

Now why would you need to shoot in low light using a high ISO when you could as well decrease the shutter speed and/or increase the aperture. For one, increasing the aperture is not an option beyond the limits of the lens. You can only increase the aperture up to the maximum value allowed by the lens. So the other option is to decrease the shutter speed to allow more light. This is possible depending on the situation. If you are trying to capture moving subjects(say a moving car) then you cannot keep a long shutter speed as you would end up capturing just a streak of color. Also, a longer shutter speed would give ghosting or blurry images if the photos are taken handheld(as opposed to a tripod). This is due to the induced 'shake' which results in longer exposures. Similarly, if you are capturing a night shot with lights in the picture, then you might end up getting streaks in the image as a result of the light moving around the screen because of camera shake.

In such cases, a compromise over the noise introduced has to be worked out and you would have to decide between decreasing the shutter speed or increase the ISO at the cost of higher noise.

Exposure

2007-10-17T16:16:00.001+05:30

Loosely an exposure is defined as the process of light entering the camera and forming an image on the lens/film.

Exposure is a term that is used widely in photography. An exposure is something which indicates that light is passing into the camera through the lens. Usually exposure is quantified by an other term depending on the quality of the photograph.

For example, one of the usages of exposure is in qualifying the image. Consider the set of photos below. Assuming that the photo in the center is how we want our image to look like, you can easily make out that the photo on the left is darker than desired and the photo on the right is brighter than desired. This means that less light than necessary entered the camera to form the image in the left case. Hence the photo was not exposed correctly, in this case the photo is 'under'-exposed. Similarly in the right photo, too much light found its was into the camera and hence the photo is 'over'-exposed. Since the photo in the center is what we need, we would say that this photo is exposed correctly.

So we have now come across the different exposure qualities. Lets say we consider the under-exposed photo. Why is the photo under-exposed? It could be because the shutter speed was too fast, or the aperture was too small or a combination of both. Similarly the over-exposed image was a result of the shutter speed being too slow, or the aperture being too wide or a combination of both. From either cases we realize that exposure is a resultant of the shutter speed and aperture. Exposure is directly proportional to aperture and inversely proportional to shutter speeds. This is the mathematical definition of exposure.

Mathematically,
Exposure = Aperture / Shutter Speed.
[Note: There might be other factors affecting exposure, but this is the relation of exposure with aperture and shutter speed]

To achieve good exposure one must choose an ideal combination of aperture and shutter speed. In the point-and-shoot mode, the camera itself has an automatic control mechanism where it would choose the aperture and shutter settings for correct exposure. In little more advanced cameras there is a shift mechanism whereby you can set an increase in shutter speed and corresponding decrease in aperture or a decrease in shutter speed and corresponding increase in aperture. You might wonder where is the necessity to modify the automatically chosen shutter and aperture settings. This part we will cover in the posts on how to get creative with aperture and shutter. For now its important to understand the relation of Exposure to Aperture and Shutter-speed.

The other usage of exposure is 'long'-exposure and 'short'-exposure. Long-exposure refers to taking a photo keeping a longer shutter speed duration while short-exposure is one where the shutter speed is very high. The reasons for long and short exposures will be looked at in the posts that deal with creativity.

Speed of Lens

2007-10-16T17:02:00.001+05:30

You might have heard from some friends about slow and fast lens. These terms result from the property of the aperture of the lens. The lenses with larger apertures are faster than lenses with smaller apertures. So that would mean that a 'f/4.6' lens is 'faster' than a 'f/8.0' lens. Let us try to understand why aperture is measured in terms of its speed.

You would have understood that the larger the maximum aperture of the lens, the more the light that enters the camera. This should be obvious by now. Also from the previous post, you would remember that the slower the shutter speed, the more the light that enters into the camera. When we take the photo of an object then the image is formed as a result of the light entering the camera. This amount of light has to be regulated and should be as accurate as possible for a good photograph. Too much or too less light and the image will not look as good as it is meant to be. Of course there are creative techniques which make use of these less-than-perfect images and we will have a look at it later.

So, amount of light is directly proportional to aperture and indirectly proportional to shutter speed. Since both apertures and shutter speeds are the property of the camera, the image that is formed depends on both the aperture setting and the shutter speed setting. Let us fix two camera/lens at the maximum aperture value and compare them. One lens is F/2.8 and the other is F/8.0. In the case of the F/2.8 lens, a lot of light is entering the camera because the aperture is wider. Now we will set the shutter speed to a desired value so that we get a good image, say 1/500s. At F/2.8 and 1/500s we get the image that we desire.

Now let us use the other lens - the F/8.0 one. Since this has a smaller aperture value than the F/2.8 lens, it would be transmitting lesser amount of light into the camera. Now since the amount of light has reduced, the image will look darker. As this is the widest aperture of the camera, we cannot increase the aperture any further to allow more light into the camera. So we are left with only one other choice(as of now) - to decrease the shutter speed. Since the shutter speed will now be open for a longer time, it will allow more light into the camera. If we decrease this setting enough then we will have the same image quality for the F/8.0 aperture as we had for the F/2.8 + 1/500s combo. This would be approximately at a shutter speed of 1/2s. So, the same image results at a slower shutter speed.

So, when taking photographs, you are limited by the aperture and hence, while you can shoot fast on a lens with a wider aperture, you will have to shoot slow using a slower shutter speed on a lens with a smaller aperture. It must be understood that the F2.8 lens can be stopped down to F8.0 since it is only a matter of making the aperture narrower. On the other hand the slower lenses are limited by the smaller maximum aperture and hence you cannot increase it beyond the maximum possible value to make it faster.

Do drop in your comments and do let me know if the reason for labeling a lens slow or fast is clear.

Aperture

2007-10-16T10:54:00.000+05:30

Above photograph is the copyright of http://web.uvic.ca/ail/techniques/

The aperture of the camera is the opening of the lens through which the light enters the camera. In the camera the aperture of the lens is controlled by a diaphragm which opens wide or contracts as per the input give by the user. The aperture can be controlled either from the controls on the body of the camera or from the lens itself(as in the case of SLR lenses) using the aperture ring on the lens.

Aperture is measured as an f-number and hence you will find the cameras displaying the aperture values as f/3.6 where sometimes even the '/' is omitted and the aperture is represented as f2.8 only. This f-number is calculated as the ratio of the focal length to the
aperture diameter. It should be fairly obvious that the larger the opening of the lens, the more the light that can come in. The increases the exposure of the image - in other words the image will appear brighter if all other parameters are kept the same. We will have a look at exposure and how it affects the other parameters of the image in a later post. When the aperture is narrower then less light enters and hence the image is darker if all other parameters are kept the same.

It should also be remembered that the larger value denotes a smaller aperture. For example, the aperture opening in f/2.8 is larger than the aperture opening in f/5.6. This is easy to understand as the number measured is inversely proportional to the aperture value.

How to read the aperture specifications:
Many of the smaller cameras would have some specification numbers written on the lens. As an example I am taking the Sony W80. As you would see from the image alongside, the specification mentioned is 2.8-5.2/5.8-17.4 on the lens. The first part is the aperture which we are looking at now whereas the second pair is the focal length or zoom range available on the lens.

2.8-5.2 essentially means that the lens has a maximum aperture of f/2.8 at the wide(minimum) end of the zoom and f/5.2 at the tele(maximum) end of the zoom. In between the two ends of the zoom range the widest possible aperture gradually reduces from f/2.8 to f/5.2 as you zoom in. The feature of a lens is maximum possible aperture value and hence this is the reason why the maximum apertures are mentioned and not the minimum ones. Generally in the compact cameras the minimum aperture value is f/8.0. At this aperture the least amount of light enters the camera.

A rule of thumb when deciding on a camera is to go for a camera which has the widest possible aperture range. For example - prefer a camera with a lens that is 'rated' F/2.8 - F/3.6 over a camera with a lens that is rated F/2.8 - F/5.2. I am not referring to aperture range here, but to the widest aperture-range. In other words, the aperture should not change too much over the entire zoom range and should try to remain as wide as possible. So, in the first case it change by a value of 0.8, whereas in the second case it changes by 2.4, and hence the first lens is the better one. Hope this is clear.

Why and how the aperture is important will be covered in the next post.

Shutter Speed

2007-10-16T09:07:00.000+05:30

Whenever an amateur photographer wishes to break out of his shell and get into some serious photography then he would have to start learning about 2 important features of the camera. The shutter and the aperture. In this post we will have a look at the shutter of the camera.

So, what is this shutter?
The shutter is something which covers the opening to the sensor of the camera. If the shutter is closed then there will be no light going to the camera and if the shutter is open then the light will reach the camera and it will be able to capture the image of the object that you are pointing the camera at. You can think of the shutter as something similar to your eye lid. When you open your eye lids, light enters and you are able to see. When you close your eye lids, no light enters and you are hence not able to see anything.

Shutter Speeds:
So, what can you do with the shutter to influence the photos that you take? You can set a parameter in the camera called shutter speed. The shutter speed dictates the duration for which the shutter will remain open hence allowing light into the sensor/film of the camera. Shutter speed is measured in seconds. If you set the shutter speed value as 1s, then that means the shutter will be open for 1 full second. If you set it to 1/500s, then that means the shutter will be open only for 1/500th of a second.

How do you think the shutter speed can influence the image formed? Think of when you were a kid and you used to burn leaves/paper using a magnifying glass. You had to focus the rays of the sun onto the paper for a good number of seconds before the paper caught fire. If you had held it for just a few seconds then it wouldn't have made a difference to the paper. If you had held it a little longer then you would have noticed that the paper start to get charred. What I am trying to say is that the intensity of light that the paper receives, is directly proportional to the amount of time for which light falls upon its surface. Similarly, if the shutter is open for a short duration then less light enters the camera, than if the shutter is open for a longer duration.

Usually shutter speeds are not mentioned anywhere on the body of the camera as a major specification. This is very much unlike the other parameters of the camera like aperture, zoom, megapixels etc. This is because not many people look for the shutter speeds when buying a camera. Usually the compact cameras have a fastest shutter speed of 1/2000s, larger(and costlier) ones have it at about 1/4000s. Semi-pro SLRs have much faster shutter speeds at 1/8000s. On the other hand the slowest shutter speeds can range from 2s in some compacts, to 8s in the majority of the compacts. Some more advanced compacts have slowest shutter speeds in the range of 30s - imagine the amount of light entering the camera at this setting. SLRs have a mode called bulb mode, where the shutter is open for an indefinite time till a pre-defined button is pressed.

We shall see how to be more creative at taking photographs using the shutter speeds in a later post. For now this is all you would need to know about shutters in cameras.

Single Lens Reflex or SLR camera

2007-09-08T10:32:00.000+05:30

What is an SLR camera? That’s the question that most of my friends ask me when they first hear about SLR or when they have some knowledge of cameras and are intending to make their first purchase or foray into the world of photography.

SLR stands for Single Lens Reflex. It’s a camera mechanism more than a technology. These days cameras are filled with technology, from the types of sensors used to the types of memory available. Most of these technologies have come into existence since the digital camera was born. SLR on the other hand is a technology that was born during the age of film cameras. Necessity is the mother of invention as the saying goes and it was this necessity that lead to the birth of the SLR camera.

Technologies or rather Mechanisms that were present in film cameras are very complicated and needs the involvement of the photographer to make use of such features. Things were not as simple then as point-and-click. The photographer would have to consider the camera as an extension of his own body to take a good shot. He would have to think and then make all the settings and then take the shot. These days things are so automated that you just have to look at something through the viewfinder of the camera and then just click and the camera does what is required. We will get to more of these in the days to come. For now lets concentrate on the SLR, what it is and how it came into being.

If you own a non-SLR film camera then you would be familiar with the basic parts of the camera. Importantly, there is the lens in the front of the camera from where the light is exposed onto the film,. Then there is the viewfinder in the back of the camera from where you try to see what the camera is seeing. Yes, I did mean ‘try’. You don’t really think you are seeing what the camera is seeing do you? The viewfinder is placed so close to the lens of a camera that within the limits of parallax you are really close to seeing what the camera sees for objects that are sufficiently far away from the camera. Let me explain in more detail.

While seeing through the viewfinder of the camera feel the front of the camera and try to cover the lens with your finger. Keep your finder in front of the lens such that the finger tip covers the lens and no other portion of the camera is covered by your palm/fist. You would of course realize from this that you are blocking all sources of light to the film. But did you realize that when you see through the viewfinder then you still get to see the whole bright world? Don’t believe me? Take a shot at this stage and see for yourself. The film is dark without any exposure although you were getting a clear view through the viewfinder. You can even try this with any non-SLR digital camera be it with zoom or without. What you see is definitely not what the lens sees. You want more proof? Hold a magnifying glass just in front of the lens on the front. You can still see the whole wide world through the viewfinder, but when you take a shot, the camera has seen it through the magnifying glass.

The secret of the viewfinder is the small opening that is there on the front side of the camera very close to the lens. This is the exit pupil of the viewfinder. In simple/basic cameras this exit pupil is in line with the viewfinder. In more expensive equipment, the exit pupil is placed as close to the lens as possible so as to reduce parallax error. Of course this would involve some costly arrangement of mirrors and prisms to bend and reflect the light to the viewfinder. This forms the basic and simple concept of the SLR camera.

There is no gimmick or mind blowing features in the SLR camera. Its as simple as ‘You see what the camera sees’. There is a complex arrangement of mirrors and prisms from the viewfinder to the lens which allows you to see through the lens. If you place a magnifying glass in front of the lens then you also get to see what the camera sees. How this is achieved and other complex mechanisms in the SLR camera we shall see at a later stage. One other claim to fame of the SLR cameras are its interchangeable lenses. This way you no longer have to stick to the same factory provided lens package. You can buy and add-on and even replace the existing lens package on the camera. This way you can get a range of zooms and other features on your camera that is only limited by your budget. These are the reasons why the SLR camera is such a sought after piece of camera equipment.

Digital Camera & Film

2007-09-08T10:22:00.000+05:30

Most of you would know how a film camera takes a photo. Its part of almost every physics text in school/college. In brief, the digital camera works on the principle of the pinhole camera. Light enters the opening of the camera, goes through some transformations, if there are lenses, and then finally falls on the film that is there in the camera. The film is coated with a chemical like Silver Iodide which reacts to light. Depending on the intensity of the light that strikes its surface a sort of a shadow is formed on the surface of the film. Where the intensity of light is more, there the reaction is greater and the surface of the film becomes darker. At places where the light is not present, the film doesn’t react and is stays light. This is why the film contains the ‘Negative’ of the image you are capturing. This negative is converted to a positive image when it is developed in the darkroom.

Now we have digital cameras whose main advantage is that there is no need to buy and keep replacing film. So how does the image form on the digital camera? These use a sort of digital film. It is a sophisticated IC chip. This chip contains millions of small photo sensing pixels and this is what records the image. Each pixel captures the intensity of the light falling on it. Another important part of the digital camera is the image processing chip. This chip receives the image from each pixel on the chip and composes this to form the actual image. How the sensor is actually fabricated and how it records the images is a advanced topic and we will have a look at this in a later stage. For now, you have to understand that the sensor and the image processor together is able to capture the light that falls on its surface and record this on the memory card that comes with the camera. This is how the digital camera has come to replace the film camera.

Camera Lens Types

2007-08-24T09:06:00.001+05:30

Some might like to categorize their cameras based on the lens type too. So we shall have a look at the various types of lenses available on the cameras in the market.

Fixed Lens Type: In these cameras, the lenses are fixed to the body. The range(zoom) of the lens is fixed and this cannot be changed unless adding on additional lenses to the existing lens. In contrast is the Removable Lens type of cameras which are mainly present on SLR cameras. I will cover SLR cameras in a different post. For now let us have a look at the different types of Fixed Lens cameras.

Internally Zooming: These cameras are very compact and have internally zooming lens elements. To the outsider, it is unknown if the photographer is zooming in on him or not as the lens barrel never pops out beyond the body of the camera. Of course the range of zoom is hence severely limited with cameras known to touch a maximum of 3x zoom. Obviously even external lenses cannot be attached to these cameras to increase the zoom as the lens is inside the camera.

As is obvious the next type of cameras are the Externally Zooming types. We shall have a look at the different types of externally zooming lenses available.

Medium Zoom: These are present in 75% of the cameras available in the market. They have an externally zooming lens barrel and they have zoom capacity in the range of 3x - 6x. These lenses can also be enhanced by adding add-on lenses and many manufacturers provide screw threads on top of the lens where one can attach add-on lenses.

Ultra Zoom: Many newer Pseudo-SLR cameras come with really large zooms. They offer the range and dexterity like no other. People who understand SLR cameras will realize that they don't need to carry around large and bulky lenses which they have to keep replacing depending on the subject that they are photographing. These cameras start with an unbelievable zoom of 10x. For people looking for really large zoom to capture far away objects frequently, this is absolutely the way to go.

Choice of Camera

2007-08-19T21:49:00.001+05:30

Maybe the very very first and important question that would come into the mind of a first time camera buyer is the size factor. Budget might well be the question, but that is the limiting factor, it is not the deciding factor. So lets have a look at how the range of sizes of camera available in the market affect the decision of the buyer.

Ultra Compact: These cameras are small, and by small I really mean small. They can range from credit card sized to the business card holder sizes. They are easily pocketable and can be really handy if you want a camera that can carried around anywhere and everywhere and you want it to be as inconspicuous as possible. The interesting thing about these cameras are, they don't employ any viewfinder to compose photography. They feature large LCDs to view and compose photographs. Some of the thin models feature internally zooming lenses and hence there is no projection from the body of the camera at all - prevalent on Sony and Nikon ranges. Generally I consider the ultra compact ones as that having a maximum of around 1inch depth.

Pros: Very Very compact, inconspicuous, light and handy, good video recording
Cons: Shutter lag, proprietary batteries, no viewfinder
Popular Models: Sony T/W/G series, Nikon S/L Series, Canon IXUS series

Compact: These cameras account for the bulk of the sales of any camera manufacturer. They are little bulkier than the Ultra Compact ones. For the most part they feature viewfinders, externally zooming lenses. They also throw in some additional features and feature better response times. Although these cameras are not really as pocketable as the Ultra Compacts, they can still easily fit in the hand and into the corners of the bags.

Pros: Small and handy, viewfinder, AA batteries
Cons: Number of models makes for tough decision making
Popular Models: Canon A series, Nikon P/xx00 series

Medium/Large: These cameras are more of a niche in the market. They are usually the favorites of amateur photographers who are looking for a good camera at a not-so-expensive price so as to get started into the world of photography. The main advantages that these range of cameras offer are the range of features and great lenses. The newer cameras in this category offer huge zooms and are even offered as a replacement for and SLR.

Pros: Great sensor/lens and hence great image quality, high performance, lots of features
Cons: Large and bulky, expensive
Popular Models: Canon Powershot Pro/G series, Olympus UZ series, Sony H series

These are the various categories of cameras avialable in the market today in terms of their sizes. There are other categorizations of of cameras which I will cover in the future.

The Photography Bug

2007-07-13T16:15:00.001+05:30

It didn't take me too long to get bitten by the photography bug. I took to photography like how a fish takes to water. There might be something to do with the genes too. Since childhood I've seen my dad do a lot of photography with the old horizontal-bar type of cameras that took 28mm film. Of course he wasn't into photography as an art but rather for the sake of keeping memories. I too loved taking photos to keep memories, but as I went on and understood the intricacies of photography I started taking it seriously and as an art form.

Everyone can enjoy taking photography in one form or another. You don't need expensive equipment to get started into photography, but of course, you must understand that better equipment always helps. The best quality and range of photographic equipment that you get these days are Digital-SLRs. Of course these cannot be termed cheap, but can range from barely affordable to the insanely expensive.

What I am going to do here is start off with the basic concepts and theories of photography and then move on to more advanced topics that deal with the art of photography and also some post processing. Do keep reading and do drop me some feedback and comments/suggestions on how I can improve the content and what all you would like to read about.