Lenses

The job of a lens is to control light.  It does this with the aperture setting on the lens.  I am not going to explain how the light works suffice to say that it in involved refraction and lots of other detailed information which is more than required for this task.  What I do understand though is the difference in the lenses and which one I would use for what I am photographing. 

There are 3 main types of lens for 35mm cameras: Standard, Wide Angle and Telephoto.  A standard lens has a focal length of 50mm; wide angle is anything with a focal length of less than 50mm typically 28mm and telephoto lens is anything greater than 50mm.   These lenses have different shapes and it is these shapes that dictate what can be captured.    For example at 50mm lens has a view of 45 to 50 degrees - I have heard a saying that a standard lens sees what you can see.  My eyes can't see clearly something that is say 300 yards away but with a telephoto lens my eyes could see clearly.  Similarly with a wide angle lens my eyes can't focus on something that expands to the left and right of my normal visiion however with a wide angle lens it can.


In addition there are also fish eye lens and macro lens.  A fish eye lens tends to give a distorted look to a photograph.  Macro lenses are for close up photography: good for insects, butterflies, tops of flowers or anywhere that you want to focus close to your subject.


On a lens you will see the make, the type of lens, the focal length range.


There is also a button for selecting whether you want the lens to auto focus or manual focus (unless you are using an old manual camera (on my first film SLR it was a totally manual camera so there was no AF/MF button)).


It is a good idea to protect your lens with a UV filter which can reduce reflections from non metalic surfaces such as glass and water.  You can also buy many different filters to give different effects to your photographs.  For film SLRs if you are using black and white film you can buy for example a red filter which can give a stormy look to your image.  Other filters include colour ones (yellow, green, orange, red, blue) which are predominatly for black and white, soft focus.  A tip I have been told is to carry vaseline around with you and this can be use on a lens to give a foggy/softer focus but I would only recommend this if you have a UV filter on and not put vaseline directly onto the lens.