Majority of the DSLRs in the market are sold with a standard lens kit attached to the body. The lens kit is usually a medium-range zoom lens having a focal range of 18-55mm with an aperture range of f/3.5-f/5.6. For the average users, the lens kit may be sufficient enough in handling their photography needs. However, for the enthusiasts and the hobbyists, the standard lens kit is somewhat lacking in features specially when photographing subjects that will require you to zoom in to get a better picture. There’s a lot of situations that will require zooming in to take a photograph of a subject, such as, in concerts, sports, school events, wedding ceremonies, theatrical plays, and other scenarios where photographers are not allowed to come near the subjects or going near a subject is not possible. To some, buying a zoom lens with a maximum focal range of 200mm or more is not practical. To be able to zoom without spending so much for a lens, teleconverters come into play…
What is a teleconverter? A teleconverter is a secondary lens mounted between the DSLR body and the primary lens that “extends” the focal range of your primary lens. Some call the teleconverters as extenders. Teleconverters can extend the focal range of your primary lens from 140% (1.4x) up to a maximum of 300% (3x), which means: If you have a maximum focal range of 55mm, assuming you’re using a standard lens kit, the focal range will be extended to 77mm if you are using a teleconverter with a 1.4 multiplier, at 110mm if you are using a teleconverter with a 2.0 multiplier, or at 165mm if you are using a teleconverter with a 3.0 multiplier.
To illustrate the effects of a teleconverter, I took the image below at 50mm which may approximate how our eyes see the world. The tower crane and the condominium is about 1.5 kilometers away from where I am standing when I took this picture without any teleconverter mounted on my gear.
Since I am using a Tamron zoom lens with a focal range of 18-270mm, I zoomed in at 270mm from the same location where I am standing and took a shot of the same scene again without using a teleconverter. As you can see, the image appeared to be nearer than what our eyes can see.
Now, I mounted my 2x teleconverter and again zoomed in at 270mm. But this time, my camera registered a focal length of 540mm. Technically, my 18-270mm lens became a 36-540mm lens with my 2x teleconverter mounted between my primary lens and the body of my gear.
Below are the photos taken in 50mm, 270mm, and with a teleconverter extending my maximum focal length to 540mm.
There are many teleconverters in the market, some are made by the DSLR makers themselves while others are made by third-party lens manufacturers. I am using the Kenko Teleplus Pro 300 with a 2x multiplier (please click on the link to see further details about Kenko’s Teleplus teleconverter).