Lenses: The complete story
If you are unfamiliar with F-stops(aperture) it might get a little confusing for you nevertheless you will find it worthwhile.
There are basically two types of lenses:
- Prime Lens (popularly known as block lens)
- Zoom Lens
Prime lens are basically fixed focal length lenses. In these lenses the glass elements don’t move. Only the aperture blades move. Because of this the picture quality is just superb and totally uncompromised. Another benefit of this is that the lens lets you open the aperture really big like f/1.4, f/2.
Having said that these lenses are difficult to use as the focal distance does not change. We have to move ourselves to get closer or farther to the subject. In situations where u need constant changing of focal length like weddings etc it becomes difficult. But if you can get used to the downsides your picture quality will be in a different league, the sharpness contrast details will be far superior.
Two must have lenses are the 50mm and the 85mm. Other popularly used are the 135mm f/2, 200mm f/2.
Zoom lens basically means that the focal length of the lens changes. So for example on a 70-200mm lens we zoom in and out 70 being the widest focal length and 200 being the narrowest. Now because these lenses have moving glass elements they are usually designed in a manner in which they give smaller(when compared to prime lenses) f-stops.
Lenses with changing minimum Aperture
There are lenses in which the minimum aperture changes with change in focal length. Eg 18-105mm f/3.5-5.6. At 18mm this lens will give minimum aperture of f/3.5 and at 105mm minimum will be f/5.6. Because of the changing lowest aperture point these lens are able to support long range in focal lengths like 18-200mm, 100-400mm.
Because of so many elements moving these lens give a slightly inferior picture quality but nonetheless their performance at optimum focal length is very good. These lenses are mostly used on crop frame cameras.
Lenses with fixed Minimum Aperture
Then there are lenses with have a fixed minimum aperture. This limits the range but gives the lens the have a bigger aperture. Eg 70-200mm f/2.8 in this lens widest focal length being 70mm and full zoom at 200, but you will still get f/2.8 at 200. Although the range is lost(lesser than 18-200) the lens will get more depth of field hence better bokeh etc. The image quality of these lenses are better than those of the moving aperture lenses and hence these are very expensive and also far heavier. There is a completely new series of lenses from Nikon and Canon which have minimum fixed aperture at f/4. Although they get one stop of light less they are very good for two reasons. One that they are much cheaper than f/2.8 lens and second they weigh much less. If you did not understand it take a break and read again it is pretty simple.
Then the lenses are classified depending on their focal length:
- Wide angle
As the name suggest these lenses are extremely wide. Usually 12-24mm f/2.8 , 17-35mmf/2.8 or 17-35f/4. Wide-angle lens are used for capturing nature, scenery and also for interior and architecture. They are also use for taking wide-angle shots during weddings. The usage is more improvised so all cannot be said.
- Mid Range Zoom
Any focal length between 24-120mm can be called a mid range zoom. Actually no hard and fast rules apply. The most popular is the 24-70 f/2.8.(I personally use the 50mm f/1.4 prime) These are a must have if you don’t have two or more block lenses in the focal range. Other good lenses are 24-105 f/4 for canon and 24-120 f/4 for Nikon.
- Telephoto Zoom
Lenses with focal length between 70-300mm are called tele-zooms. The most popular lens being the 70-200 f/2.8 for both Canon and Nikon. It is good to have one of these to use on a day to day basis. Other good options are 70-300 f/4.5-5.6 or the 70-200 f/4.
- Super Telephoto Zoom
Lenses upwards of 300mm are called super tele-zoom. Nikon has a 80-400 canon has a 100-400. Mostly use for sports and wildlife. Honestly I know less about these.
Special Purpose Lenses
These lense are are for extremely specific purpose and are of no use to the usual every day photographer.
- Fish Eye Lens
A fisheye lens is an ultra wide-angle lens that produces strong visual distortion intended to create a wide panoramic or hemispherical image. The image below will make more sense.
- Macro Lens
- Macro lenses specifically designed for close-up work, with a long barrel for close focusing and optimized for high reproduction ratios. As the name suggests they are used for clicking extreme close-ups or small objects.
- Perspective control or Tilt-Shift Lens
It is difficult to explain and outside the scope of this article but if you are interested - http://en.wikipedia.org/wiki/Tilt–shift_photography