Camera Lense basics to help you understand the differences between lenses and when they are used.





Something I battled with was Camera lense basics - which one to buy, what that lense would do and whether it would be suitable for what I wanted in my images.

Lenses are expensive and the last thing you want to do is buy a one and find it is no use to you.

Here are some basic explanations to at least clarify the terms and different types of Camera lenses to help you to understand the options and in turn understand what people are talking about when you are seeking further advice.

DSLR cameras allow you to change lenses, compact digitals have a fixed lense cannot be removed but zooms (focus in).

There are two main categories of lense - Prime lenses and Zoom lenses.

Prime Lenses

Prime lenses do not adjust their ‘focal length’. The view is fixed and you cannot adjust to bring the subject closer or move it further away in your viewfinder.

The Camera lense will be labeled for example, as 28mm or 50mm with only one number for each lense.

Zoom Lenses

Zoom lenses adjust by turning a ring on the outside of the Camera lense body, bringing the subject in the viewfinder closer or moving it further away. A Zoom lense has two numbers in its name like 18 – 35mm or 17 - 70mm.

The main difference between the two is the Prime lense's ability to take sharper images and usually able to take better images in lower light circumstances than with a Zoom at the same settings.

The greater flexibility that comes with a Zoom lense sacrifices the precision that comes with a Prime lense. Usually Prime lenses are cheaper.

There are then several ‘sub-categories’ of lenses

  • Macro lenses
  • Wide angle lenses
  • Fish-eyed lenses
  • Mid-range lenses

Macro Lenses

These are used when you are going to be taking photos of subjects which are small (usually) and very close up.
Some examples are 50mm, 60mm, 100mm, 150mm lenses

Most popular are 60mm and 105mm, both have pros and cons with the 60mm being a little more versatile but requiring you to get closer to the subject which has drawbacks when the subject can move away!

Wide Angle lenses

Wide angle lenses allow you to be closer to a subject or scene and get more of the scene into your image than may be possible with another lense.

Bear in mind that the closer to the subject you are, the less water between your camera and the subject, therefore the sharper and better colour you will have as a result, a wide angle lense allows you to be closer and still get the entire subject in the frame.


The situation with the photographer stepping further and further back to get the group he is photographing into the picture is exactly when a wide angle lense comes into play, the photographer would be closer to the group and getting the entire group into the picture with a wide angle lense than he would with a standard lense.

Fish-eyed Lenses

These lenses are also wide angle lenses and produce a curved image, the angle of their coverage is wider than a standard wide angle lense (rectilinear wide angle). Straight lines will appear curved and objects in the outer edges of the image will appear smaller.

For compact digital cameras, there are many suppliers of add-on lenses which fit onto the outside of the housing lense cover to give you the functionality of either a macro lense or wide-angle lenses amongst other accessories, many of which are quite effective and convenient for taking on and off underwater.

Mid-range Zoom lenses

There are camera lenses with focal lengths of between 17 and 70mm known as mid-range Zoom lenses. The lenses falling into this category are good for a wide range of photography situations from close up shots to the wider angle requirements like taking pictures of sharks and the larger sea life or schools of fish.

They will not get the quality in the different situations where you should be using either a macro or a wide angle lense.

For more information on basics like Camera lenses click here


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