Macro photography with a common telephoto lens

Crackling forest grasshopper taken with a 70-300 mm zoom and extension tube.

Kit lenses are not known for their great versatility, especially when it comes to their macro function.  They are designed with the idea of being general-purpose lenses that are relatively inexpensive.  They typically have only a mild zoom range of 3 to 4 times.  Common kit lenses include the 18-55 and the 70-300 zooms.  

If you have a camera system comprised of one or two of these lenses, consider adding an extension tube set to the mix.  Extension tubes are just that - tubes that contain no glass elements that you place between the lens and the camera, extending the lens away from the body.  A set usually comes with three tubes that can be used independently or stacked in any combination.  

The upside of an extension tube is that it allows a lens to focus on a subject at much closer distances than would otherwise be possible.  I photographed the above image of a grasshopper using a D7100 with a 36 mm extension tube and a kit 70-300 mm lens.  The combined zoom and extension tube allowed me to focus closer than I otherwise could and yet keep enough distance so as not to disturb the resting insect or affect the light falling upon it.

Focal lengths, extension tubes, and zoom lenses are funny things.  There is an interesting mathematical relationship involved which I will not go into here, but there are plenty of websites available that will fill you in on the details if you are interested.  Suffice it to say that focal distance is inversely related to extension tube length.  The further you move the lens away from the camera's sensor the closer you can focus.  Focal length plays an important role here where wide angle lenses (< 50 mm) can only effectively use short tubes while telephoto lenses (> 50 mm) can use longer tubes.  The further away from that 50 mm mark the shorter/longer tube length is functional.

The nice thing about the zoom is that you can play with varying focal lengths and focus points to alter lens magnification.  If you want to get close to your subject, use a lower focal length with any given extension tube.  If you want to be further away from what you are shooting, zoom out and back up.  The magnification won't be as much as when zoomed in, but you are less likely to affect your subject.  It takes quite a lot of playing to find what works best for any combination, but then that is all part of the fun.  

The downsides of extension tubes revolve around having to remove your lens, the risk that there may be improperly seated lens contacts, especially with multiple extension tubes, and that you have to remove the tube if you want to go back to your normal shooting mode.  However, the inexpensive addition of these terrific little add-ons takes your ability to focus closely to a whole new level.  You will quickly discover a whole new world of macro photography that you could never experience before.  It's well worth the investment.

Thanks for reading.

Eric Svendsen     www.ericspix.com