Basic terms you must know- in easy to understand language

What is a camera? How does it function. Lets try to understand it in a simple manner. Camera is a light tight container and does not allow any light to enter till we want it to. The process of allowing the light to enter the camera for a certain time duration, through an opening is what is called "taking a picture" in simple words. this opening in the lens is called "aperture" and the duration for which the film is being exposed is called "shutter speed". To take a picture you need to release the shutter, i.e uncover the film/sensor. At this point of time the aperture opens to the size that is set on the camera and allows the light to enter through the set size. The momment the film gets the light for the set time frame the shutter covers the sensor/film again and is back in position, ready to take another picture. This combination of shutter speed and aperture (at a given ISO) is called exposure. We may have various combinations depending on the desired effect in the photograph.


The diameter of the lens diaphragm can be changed by turning the aperture ring. This dictates the brightness of the image reaching the film. Moving to the next f-number either halves or doubles aperture size. Aperture size also effects depth of field.

shutter speed

SPEED - The shutter speed is the duration for which the aperture remains open and hence the film gets exposed. Do not confuse yourself with the word "speed". It is not the speed with which the shutter moves.The shutter can be set at different speeds, which determine the length of time the film is exposed Moving the shutter speed dial to the next stop either doubles or halves exposure time.


Slow shutter speed

At slow shutter speed, since the guy on the divider is not moving, is exposed as stationery while the Auto rickshaw in the background is rendered as a blur.

At f11 the shutter speed dropped to 1/15th of a sec while shooting these cyclists in Malaga, Spain.

While the Aperture is opened up to f4 but  still there is significant depth of field due to the focal length being 32mm. The Higher shutter speed of 1/800 second has frozen the moving ride. 
To maintain the same and correct exposure, at 32mm itself, the aperture was closed down to f/22 at aperture priority mode leading to a change in the shutter speed to 1/20th second. Only the moving part of the ride is rendered as streaks in the direction of movement but the stationery part, the figure in the centre is quite sharp.

The Model in this photograph was asked to wave the fabric as the sensor was exposed. The Flash /strobe froze the model, who was anyways not moving and for the remaining period of exposure the ambient light recorded the blur of the fabric. Twilight is a good time for such shots.

Freezing the moment means capturing the right moment especially at the peak of the action on our film or sensor. Usually with fast moving subjects this moment lasts for an extremely brief period and it is very easy for us to notice that moment with our naked eyes. Yet we have to be very fast and alert to anticipate and release the shutter at the very right moment. It is often said that, if you saw the action in the viewfinder, you probably missed it. (the viewfinder is blocked by the mirror which moves up making way for the light to strike the film, so we never see the “actual moment” caught on the film.   

FOCAL PLANE -        
This is the plane where the film/sensor is positioned inside the camera body. This is where the image is formed when the lens is focused on the subject. Know more...

There is a setting on the lens which lets you see more or less through the viewfinder.If you move this dial in aprticular direction, then you see less area but you see more far off area. This changes the angle of view. Decides how much is to be included. For example, if you are shooting a group of 5 people, from the same distance with a wide angle/short focal length you may be able to include all and with a telephoto or long focal length you may be able to get only one person in the frame. framing and focusing are two different things. Framing is concerned with how the photograph is composed and focusing is concerned with how sharp the subject is. More about focal length.

This is the dial on the lens which lets you focus / keep a subject at a specific distance at sharp focus. This decides the sharpness or blurness in the photograph

out of Focus Focused

The camera focuses itself at the selected focusing point. Cameras have a number of points visible in the viewfinder which may be chosen as per the position of the subject in the frame. Some people feel that they should focus manually as a learner. In fact autofocus saves a lot of precious moments which may rather be used for decisions regarding the composition and aesthetics rather than rotating and struglling with the focusing dial of the lens. However, there may be certain situations when autofocus may get fooled and not work very well. this is when the human intelligence may be utilised by focusing manualy. Also, manual focusing may be prefered  by many photographers for macro photography.

BLUR- when the image is not sharp. Can be either due to wrong focusing r due to the camera shake. If the focus is at a point closer or away from the subject distance and there is not enough depth of field, the subject will be blured
If the camera is hand held and the shutter speed is lower than 1/60th sec the camera movement will get registered in the photograph. Ways of reducing the Blur.

Besides the focusing point (which you may have achieved with the focusing dial) you may still keep the element at other distances in focus or out of focus. If everything or most of the things in the picture appear to be very sharp, it means there is great depth of field. If only the main subject is the focus and the rest of the elements in the photographs are blurred, the depth of field is shallow.

Shallow Depth of field- The Bulb is out of focus and the wires are almost non existent being too blurred Bulb and the wires are relatively sharper, though not as sharp as the Subject itself.

Shallow depth of filed / opened aperture

More Depth of field. Closed aperture. Camera has been focused on the hand in both the cases.

Depth of field depends on three factors-1) inversely proportional to Aperture (2) inversely proportional to Lens focal length (3) Directly proportional to  Distance between camera and subject.  More about depth of filed             

Exposure is the combination of aperture and shutter speed at a given ISO (sensitivity of the film/sensor) Also check Exposure triangle.

Normal /correct exposure Over exposure Under exposure

OVER AND UNDER EXPOSURE- As the name suggests, images brighter or darker than what they should be are over or under exposed. More or less than the right amount of light has exposed the film/sensor

HIGH AND LOW KEY- An images with overall highlights or bright areas is called a high key picture whereas a low key picture is the one with overall darker tones. This does not mean that the images are over or under exposed, just that these inherently contain tones on the brighter or darker side. Check more here.

Metering is the way the camera interprets the existing light and suggests a suitable exposure.The metering modes or the exposure decides if the image is brighter, darker or the same as it exists in reality. generally there are three metering modes- multi pattern, centre weighted and spot. More.

How the subject has been framed or positioned in relation to other elements in the photograph.

This dictates the sensitivity of the film or the sensor. More is the number relatively less  is the light required to expose the shot. If the iso is more you may either be able to close down the aperture more or you may be able to set a faster shutter speed. However, one should go for a higher ISO only if there is no other option as it leads to more grain in film and noise in digital photography. For example, if you are shooting in low light situation without a tripod, you may opt for a higher ISO so as to enable you to shoot at a higher shutter speed atleast at 1/60th sec handheld without camera shake. Also in such a situation if you are trying  to capture a moving subject, tripod may not be of much help as it takes care only of the camera movement and not of the subject.

ISO in film and digital
Film Digital
The light falling on the fim reacts chemically The reaction of light on the sensor is an electronic process
ISO remains same for the whole film since it is an electronic reaction, sensitivity of the sensor can be changed for any shot
Irreversible reaction irreversible, but to some extent  effects may be controlled through softwares.


TRIPOD -A support for the camera to avoid camera shake. 


CCD- charged coupled device.
This is the sensor fixed at the focal plane where the image is formed when a photograph is taken. In other words,  when exposed to light it reacts electroniically to form an image. (On a film, this is a chemical reaction) This is actually digital information which is further transferred to the memory card.  Generally people consider the number of pixels on this sensor but the size of the sensor is also important. A 6 megapixel camera would have 6,000,000 pixels with 3 across the length and 2 across the width of the sensor.  Full frame sensors are the ones which are of the same size as 35mm film. similarly full frame sensors of medium format digital are equivalent of the size of a 120mm film (6x4.5cm)
More the number of megapixels- beTter is the picture quality.  Also bigger is the sensor size - better is the picture quality. making large sensors is more difficult and expensive, which is why companies market their cameras around the numbers. Having more number of pixels on a smaller sensor does not lead to improvement in quality.

CMOS-  Complimentary Metal Oxide Semiconductor. Some cameras have a CMOS sensor instead of a CCD.

RAW- as the name suggests, this is how the image is shot and stored when photographed. This is the unprocessed form of information and any alteration on this with the software is almost as good as changes made during the original exposure. If your exposure was not correct while taking the picture you can still correct it but don't get into the habit of shooting wrong. Ideally, one should always shoot in RAW. Even if you need to use jpeg images, it is still better to convert it using the software than the camera. The camera always shoots in RAW and internally converts and stores in jpeg on the memory card.
If you are unsure of your skills it rather safer to shoot in RAW, than to shoot in JPEG. Also, on the colour calibrated computer monitors, one has a better control to fine tune the exposure, white balance, saturation, contrast etc. Once again, this does not mean that you shoot wrong. There is nothing to beat-shooting right to begin with.

JPEG (Joint Photographic Experts Group) is the name of the organisation that developed this file format.  One of the most popular formats, JPEG can highly compress the data resulting in a very small file size, good for web but lower in quality. JPEG is lower is size at the cost of the quality. The compression is lossy, that is, it throws away image data while compressing And every time one re saves the file as JPEG, it compresses and loses info leading to further degradation in quality. For example, if you work on the file, save it. next time you work on it and then save as.....every time you save the file as JPEG, you are deteriorating the picture quality. Even if you shoot on JPEG because you do not have a higher capacity card, it is a good idea to save it as TIFF and then work on it. Saving in TIFF will not improve the quality but will not degrade it further.

TIFF- this is the most popular lossless file format. While saving one may choose to go for LZW compression, which is a lossless compression, otherwise when saved as TIFF the file maintains the image quality but the file size is much larger than the JPEG. On a regular screen one may not notice the difference in JPEG and TIFF but the different is evident in printing and also on the screen when blown up to about 500% and compared together. It s always a good practice to do all your processing on TIFF files and never on JPEGS. later these heavy files may be saved as JPEGS for web or circulation and the heavier TIFF files kept safely as  a back up.


This is a reusable recording media used in the camera to write the image as it is recorded on the sensor. Compact flash (CF) and Secure digital (SD) are the most common ones. Like a hard disk, these are also vulnerable to physical shock. Never drop them. Keep the contacts clean and insert them in the camera or the card reader very carefully so as not to bend the delicate pins in side the card slot of the camera.