Pixiq

Most digital SLR cameras come with what are called “kit” lenses. These are typically 28-83mm (in 35mm focal length) zoom lenses that go from a modestly wide angle to a nearly telephoto one. But this is a pretty limited focal range that a lot of folks discover they grow out of quickly. But for the armchair photographer and the Sunday snap shooter who wants to expand their vision but are turned off of having to buy an expensive additional lens for their dSLR, there is an inexpensive alternative.

And that is to get inexpensive accessory conversion lenses. These small lens attachments are simple to use. They just screw into the filter thread in the front of your existing kit lens and you are ready to shoot.

Best of all if you have a camera with a fixed, non-interchangeable lens, like a superzoom (bridge or EVF type) or a Point and Shoot, you can get attach the conversion lenses directly onto the lens filter screw or via a special adapter.

There are two types of accessory conversion lenses, wide angle and telephoto devices. These all generally change the focal length of your original lens without causing any light loss at the sensor. Note that there is a type of telephoto conversion lens that mounts between the lens and the camera body but it causes a stop or two of light loss, so I’m not too fond of it.

I particularly like wide angle converters because they literally help me get out of tight situations. The power of a wide angle converter is listed as .80X 0r .75Xor .50X or .40X. This refers to how much the conversion lens alters the lens you are using it on. With a kit lens set to its widest focal length of 28mm to find its new focal length multiply the conversion lens factor by the original focal length. An .80X conversion turns a 28mm lens in the equivalent of a 22.4mm (28mmx .80X). Similarly a .50X turns a 28mm into a super wide 14mm lens—which is just about a fisheye lens.

On the other end of the spectrum are the telephoto conversion lenses. These increase the focal length of the lens they are mounted on. They range in power from a modest 1.4X to killer 4X power.

I’ve seen “macro conversion lenses” marketed on eBay as part of a wide angle/macro conversion lens, but these are really just single power close-up lenses rather than a true conversion lens.

But there is no such thing as a free lunch.

Conversion lens vary in quality and even the best are limited by how much they can change the focal length of a lens. My experience is that bigger the change, the lower the image quality. For example my .80X wide angle conversion lens is a superb optic that produces an image quality that is equivalent to my lens without it. You can see that in the enlargements of sections of images shot with and without the device.

When I switch from my .80X to a .50X power conversion lens, problems start right away. First the corners of the frame go dark (this is called vignetting) and the detail at the edges of the frame become soft and badly defined. Similarly, a 1.4X telephoto conversion lens will produce very close to the same image quality as the lens it is on, but pushing past 2X you begin to see image quality loss.

Generally conversion lenses range in price from about $30 for a generic third party device to over a $100 for a proprietary brand name model, well below what you would pay for a new interchangeable lens.

Conversion lenses can be found at the usual outlets for camera equipment as well as eBay. And remember to get a conversion lense that has the same size filter thread as the adapter or lense you are using it with.

Top photo: Soap display, a wide angle close up taken with an .80X conversion lens on my kit zoom lens at 28mm.