The single lens reflex (SLR) camera is most photographers idea of a serious camera. SLR means that the same lens is used for viewing and taking pictures. A mirror in the body directs the light from the lens up into a prism for viewing, then flips up out of the way just before an exposure is made. This gives you a good idea of what you are going to capture through the viewfinder.
Though costlier to buy, own and maintain, SLR cameras are more versatile and powerful than regular point and shoot cameras. They provide you with better control over various variables that have a direct bearing on the image quality. Its USP includes accuracy, large and bright optical viewfinder, fast operation and multiple control options, excellent image quality in low ‘available’ light situations when it is necessary to use higher ISO speeds and interchangeable lenses.
But before you rush to the nearest store to arm yourself with a digital SLR system, ask yourself some basic questions and decide on the camera accordingly. While point and shoot cameras come in standard one-piece packages, SLRs are sold as a system just like home furniture. You can mix and match the various elements to assemble a system that suits your need and your budget. A digital SLR camera system, complete with lenses and accessories, can cost anywhere from Rs 25,000 to Rs 4 lakh.
Body & sensor
A digital SLR system includes a body, multiple lenses, flash units, various connecting cords, storage media cards and a software to edit or retouch images on the computer. In a digital SLR, light passes through the lens, its aperture and is finally captured by the sensor located at the back of the camera body. While lens manages the magnification of the subject, aperture decides the amount of light to be passed on the sensor and sensor converts the light falling on it into an image. So selecting a right SLR system means making the right decision about lens — its magnification and aperture, camera body and its sensor.
You must also note that, over longer term, investment in lenses usually dwarf the cost of a body. It is thus important to choose a system whose manufacturer makes the lenses that you may need in future and whose system is popular enough that you can borrow or rent special-purpose lenses for uncommon situations. Each camera system has its own lens mount design and a lens that works on, say, a Nikon camera cannot be attached to a Canon body and vice versa.
When selecting a body your defining criteria should be the sensor size. Larger sensors offer lower noise at high ISO settings and are therefore essential for taking pictures in low light conditions. The best light for photography is typically fairly dim such as overcast sky, setting-sun , dawn or twilight. Unfortunately, the cost of manufacturing a sensor goes up exponentially with size and the largest sensors can cost more than a car.
Megapixels
Next to look at is the number of megapixels — measure of resolution, provided by your camera. However you must note that not all pixels are created equal. Resolution is important if you intend to make large prints. But dynamic range, that is, the ability to capture detail within bright highlights and dark shadows, is more critical in many situations. If there are 8 megapixels spread out over a sensor that is 4 times larger than the sensor in a point-and-shoot camera that means more photons of light will fall on any given pixel.
Lenses
Lenses are specified by focal length in millimeters and aperture, a ratio between the diameter of the lens and its length. The longer the lens, the greater the magnification. A 50mm lens gives approximately the same perspective as normal human vision, while a 400mm lens view is similar to looking through 8X binoculars and a 20mm lens is a dramatically wide angle.
Lens apertures or f-stops have the following full steps: 1.4, 2.0, 2.8, 4, 5.6, 8, 11, 16, 22. Each step represents half as much light being admitted to the sensor. It’s best to start with a fixed focal length with low fnumber . Now, when you go out to shop for a SLR you know what to look for. Happy shooting.