Tuesday, 29 May 2007

What is a Conversion Lens?

What is a Conversion Lens?

A question I get asked is “How can I improve the capacity of the lens on my camera?”. With many cameras the simple answer is you cannot. There are though a small number of consumer digital cameras that allow you to attach a type of lens called a conversion lens. This is sometimes known as a lens converter.

What Digital Cameras Can Accept Conversion Lenses?
When it comes to lenses there are three types of digital cameras. The first is a typical consumer model where you cannot add any enhancements to the lens that has been built into the camera.

The second is a digital SLR camera. This type of camera does not have a lens built into it at all. In fact the camera is just a camera body without a lens. Lenses are then bought separately and attached to the body. The big advantage of this type of camera is that you can buy specialist lenses.

The third type of digital camera already has a lens built in, but you can buy conversion lenses to increase the capability of the lens you already have. There are not all that many cameras capable of using a conversion lens. Canon and Sony probably supply the widest choice of cameras that are able to accept this type of lens. Fuji and Nikon also have a small number of models offering this capability.

Types of Conversion Lens
There are three common types of conversion lens. These are telephoto, wide angle and macro. If you add a telephoto conversion lens you will be able to zoom in closer to your subject. A wide angle lens increases the scope of the lens to cram more detail into the shot. For example on a landscape shot you can increase the width of the scene you can get into the picture. Macro lenses are added to improve the quality of close up shots. This type of lens is not as common as the telephoto or wide angle converters.

Magnification Factors
You will see conversion lenses denoted as 1.75x or 2x or 2.75x or something similar. Taking the simplest example of a 2x lens you apply this factor to the length of lens already on your camera to find the new lens capacity. So if your camera has a 3x zoom adding a 2x converter will change it to a 6x zoom lens. A wide angle conversion lens will have a factor of less than one. An example of this would be a 0.75x lens. If your current lens had a focal length of 35mm (when converted to its 35mm equivalent) adding a 0.75x lens would give you the equivalent of a 28mm lens.

What Else Do You Need?
In most cases before you can add a conversion lens you also need to add a lens adapter. If you look closely at the lens on your camera you will notice a thread on the lens. Your lens will also have a thread size in mm. It is rare for a conversion lens to be available that exactly matches the thread size, so the adapter sits in the middle allowing the camera lens and conversion lens to meet.

Where Can You Buy Conversion Lenses?
Conversion lenses are not always that easy to get hold of. To save hunting around I would suggest going straight to your camera manufacturer and asking them where you can find a local retailer or where you can buy online. If you are not sure of the conversion lens and adapter to fit your camera I would also recommend discussing this with the helpline of your camera company.

A list of help lines can be found at: digital camera helplines

N.B. Conversion lenses are also available for standalone lenses for digital SLR cameras.

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