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My Nikon 105mm f/2.8G lens gives a 1:1 magnification which is very good for macro work, but some people may wish to photograph images of a higher magnification and truly delve deep into the miniature world of macro photography. I felt like this and began to explore the options available.
Canon users can wield the astonishing MP-E 65mm f/2.8 1-5X Magnification lens, but Nikon users have no such option with a single lens/ apparatus set up. The Nikon ‘Bellows’ option can be costly but can reputably give users an amazing 22X magnification (PB-6E Bellows with extension). Another option is by using a ‘close up filter’ attached to your existing lens. This is the same as putting a magnifying glass in front of your lens, but again, can be costly as the best quality glass is very expensive and cheaper glass would compromise the image quality. After doing my homework, posting on the forums and reading all the other posts about macro photography, I opted for another option, Extension Tubes. Without going into the technical side too much, they are just ‘tubes’ that alter the focal length of the lens to the camera, allowing you to get ‘closer’ in to your subject. They sit in-between your lens and the camera housing.
These tubes vary in price from around £15 for a single tube to £300+ depending on make/ model and functionality. I opted for a rather modest Kenko Automatic Extension Tube Set which comprises of a 36mm, 20mm and 12mm set for £92, in Nikon AF mount for use with my Nikon D90.
The Automatic tubes electrically connect the lens to the camera by contacts like the ones at the end of your lens and inside your camera housing, so you can still use functions like auto focus, aperture select and TTL functions.
The photograph below shows a shot of a ruler taken at the minimum focal length (1:1 magnification) with a Nikon 105mm f/2.8g lens.
The next photograph shows the magnification with the 20mm and 12mm attached, also taken at the minimum focal length giving maximum magnification.
The last picture shows the maximum magnification with all the tubes attached.
With all these tubes attached you do add to the overall length of the camera lens and it can prove a little cumbersome when manoeuvring.
With all the tubes attached you get an approximate magnification of 1.8:1 with the 105mm. The box comes with an instruction leaflet that explains how to work out the magnification and gives an example of a 50mm lens of having a maximum of 1.47:1.
|105mm Macro - Snail 1cm across its opening.||12+20mm Tubes attached.|
|All on: 12, 20, 36mm tubes attached.|
There are a few drawbacks to these tubes. Many of you may know that a macro lens DOF is very small anyway (maybe 3mm on a 105mm at f/2.8G) and by adding the Kenko tubes and increasing the focal length, it decreases even more, the more tubes you attach. You can’t use a lens hood because your maximum focal length dramatically reduces with infinity becoming unusable. The biggest drawback I found was my own doing, by getting even closer to your subject and having to find the right focal length, you can quiet easily startle yourself when the big hairy spider comes into focus!
Article by Andy Cundell.
Kenko Automatic Extension Tube Set DG Specifications
|Effective Magnification||No Data|
|Fitting||Camera body mount|
|Box Contents||Front & Rear Caps|