In this blog, I make an effort to simplify the concepts used in photography.
Optical zoom v/s digital zoom
Optical zoom uses the physics of optics to enlarge or reduce the image using lenses of different focal lengths. In the photographers’ language, the zoomed-out position is called “Telephoto” (T) & the zoomed-in position is called “Wide-Angle” (W).
On the other hand, digital zoom magnifies the individual pixels of the ordinary sized photographs. So, one gets a magnified image alright; but, at the cost of the image clarity. Hence, when analyzing the capabilities of any camera, it is wise to take the digital zoom out of the equation & considering only the optical zoom characteristics.
Aperture is the opening in the lens of the camera. This is what determines the amount of light falling on the image sensor (the analogue of a film in a digital camera). Aperture is denoted using what is called as “F” number. The aperture size & the F number have an inverse relation. Thus, a large aperture has low F no in the ranges of F1.8, F2.8 etc. Small aperture has a high F no, like F8, F16 etc. Representations of aperture sizes are also made as f/8, f/16 etc
Shutter Speed is the time for which the shutter allows the light to enter through the lens. If the shutter speed in a camera reads 1/125, it means the aperture is opened for 1 by 125th of a second. Some of the cameras have shutter speeds in excess of 16 to 32 seconds. Seconds are represented using the ‘ mark.
ISO refers to the sensitivity of the image sensor to the light falling on it. ISO representation is based on the speed rating. ISOs ranging from 50, 80, 100, 200, 400 etc can be seen in various cameras. The lower ISO ratings mean the image sensor is less sensitive to light & can be ideally used in well-lit conditions. As the speeds increases, their sensitive to light also increases. Hence, these come into better use as the lighting decreases. But, this means that the fainter light signals also get recorded now, resulting in the appearance of 'grains' on the photo, which is called “Noise”.
Flash is the external light which one provides to fill-in for the lack of natural light at the setting, in order to attain a proper exposure. Fill-in flash can also be customized in many of the cameras, having positive as well as negative ranges.
Thus, we come to Exposure, which is the end-result of all these – Aperture, Shutter Speed, ISO setting, Flash – put together. If the subject appears optimally bright, the photo is said to have a proper exposure. If the photo comes out with dull & insufficient lighting, then the photo is said to be underexposed. Overexposure is when the photo appears too bright. Hence, what all photographers strive for is the optimum exposure of the sensor.
Depth of Field (DOF) is the amount of the subject which is in focus. If the whole image is in focus, it is said that there is a Great DOF. This is desirable usually when capturing sceneries or in landscape photos. On the other hand, if only a part of the image is in sharp focus, with the rest being blurred out, then, it is said to have a Shallow DOF. This is sought-after in cases of portrait (close-ups of people) photographs, so, as to lay emphasis on the subject & not the surroundings.
Regarding the different aspects & terms used in photography, I found a very appropriate analogy on the net. Let me share it with you. Consider a hosepipe conveying water to fill a bucket. Here, the diameter of the hosepipe is like the aperture of the lens, regulating the amount of light passing through the opening at any given time. The duration for which the tap is kept open corresponds to the shutter speed. The speed of the flow of water through the pipe corresponds to the ISO speed in the camera. And finally, the amount of water collected in the bucket refers to the amount of exposure.
Let us consider this. If we have a narrow pipe (small aperture = large F no), then we will require the tap to be kept open for a longer time (higher shutter speed) & with optimum speed of water (ISO setting) to fill the bucket (optimum exposure). Keeping the other settings constant, if we turn off the tap half-way through, the bucket will not fill to the brim (under-exposure). Keeping the tap open longer (lower shutter speed) will result in excess of water in the bucket (Over-exposure).
Similarly, keeping the shutter speed constant, if the aperture is increased (lesser F number), there will be over-exposure. Decreasing the aperture size will result in underexposure.
Another important thing to be kept in mind while photographing any object is the Rule of Thirds. The basis of this ages-old rule is that if you were to divide a frame into thirds, both ways-horizontally & vertically, the points of intersection are the points where your subject should be placed in order to be most interesting, while also being most pleasing & easy-on-the-eye. The photos taken keeping these rules in mind tend to grab instant attention. However, these are actually just guidelines, not absolute rules. Feel free to experiment with different positions.
All said and done, you don’t get good photographs by just learning about the different aspects of it. You must go out & shoot as many photos as possible, letting your creativity play its role, looking at things from a different perspective. Shoot multiple snaps, try out with different settings, compare & decide; you can always delete them later. With the advent of the digital cameras, photography isn’t such an expensive hobby now. Knowledge of these things just helps you to get photos which are closer to what you had in mind while shooting that snap!!!