First of all we will understand the concept of focal length of a lens. Focal Length is the distance between the focal plane(Image Sensor) & focal point of lens.
Lower the focal length = more area captured by lens
Higher focal length = less area captured by lens
On the basis of viewing angle there are three types of lenses
Normal lens = 50mm (equivalent to normal human eye)
Wide Lens = any focal length less than 50mm. e.g. 14mm, 24mm, 35mm etc
Tele Lens = any focal length greater than 50mm. e.g. 85mm, 100mm, 135mm, 1200mm and more
On the basis of working of lens these are categorised into two types. Zoom Lens And Prime lens.
Zoom Lens are the lens which have a “range” of focal length. These lens covers a variety of focal length and image can be zoomed in or out before capturing. These lens gives freedom to the photographer to capture at any available focal length without moving from his place. These are further divided into three classes. Wide to Wide, Wide to Tele and Tele to Tele.
Wide to wide zoom lens cover both the focal length in wide angle segment only. These lens are best suitable for shooting Landscapes or wherever we need a wide angle view. e.g. Canon 17-40mm(Full Frame), Canon 10-18mm(Crop Frame), 18-55mm(Crop Frame), Nikon 16-35mm and many more.
Wide to Tele zoom lens are very useful and popular ones because they give complete ease to shoot daily life images or covers almost the need of all photographers genre(Wedding, Portraits, Landscapes, Journalism etc.). These lens have a range from wide to tele angle. eg. Nikon 18-200mm, Canon 24-105mm, Nikon 24-120mm etc.
Tele to Tele zoom lens are useful in wildlife photography and astronomical photography only. These are a bit expensive lens and are used by professionals usually. eg. Canon 100-400mm, Tamron 150-600mm, Nikon 70-300mm etc. Some with lower tele focal lengths are used for Portraits, Journalism, Event photography also. eg. 70-200mm is very popular lens from various brands. and other are 55-250mm, 55-200mm.
Prime lens are the lenses which have a fix focal length. the most commonly used prime lens is 50mm f1.8. This is the best lens to start with. This lens is available from most of the brands in the market. The cheapest one is available from a Camera brand is Canon 50mm 1.8 rest all the camera manufacturing brands provides the 50mm 1.8 of their brand is priced high than the later. Some more cheaper one are also available form third party lens brand. There is no compromise in the quality of these lens from several brands but the only thing make them low priced or high priced is the no. of consumers for a particular brand. There and wide and tele prime lenses are also available in the market. eg. nikon 20mm, 25mm, Canon 14mm, 24mm, 35mm, 100mm, 135mm, 800mm and 1200mm. Any of the prime lens does not have any zoom function. These lenses are fast focussing lens. Their result in terms of quality and depth are also better than the zoom lens.
There are two special type of prime lens which we will discuss about are Fish-Eye lens and Tilt-Shift lens.
Fish-eye lens named so because their front element look like a fish eye and these covers an angle of around 180 deg like a fish eye. These are also called the ultra-wide angle lens. eg. Canon 15mm. Most of these are prime lenses, but some brand have zoom function in these lens also. eg. Canon 8-15mm,
Tilt-shift lens are very useful in product photography, Archival Photography, Corporate Building Shoots etc. as they can avoid the reflections coming into/from the glossy surfaces of the products and can change the perspective of a monument or building. These lens changes the view of upto 8-9 degree angle which is sufficient enough to avoid the reflections and shoot the desired image. eg. Canon 17mm, 50mm, 90mm etc.
However, the things which make prime lens better than any other lens are fast focussing system, better photo quality, better depth of field control and mainly the Aperture. Wider the Aperture opening better the lens as it allow more light to come in, better for low light conditions. So, one before purchasing a Prime lens should go for the lowest f/no. lens fits into budget.
Looking forward for your queries…