DIY macro extension tube

Taking quite a number of studio food images recently, we constantly stumble upon need of macro lens. Neither of our lenses are macro model nor can we afford new one just for fun. So I started exploring topic of extension tubes. All comes to three choices. Use the Nikon original ones that preserve full functionality of your lenses but cost pretty much similar amount of money to some used macro lenses. Or you can buy cheap extension tubes from eBay that cost next to nothing but provide no connection connection what so ever. That pretty much rules out all those newer lenses that don’t have aperture ring. There is a company called Kenko that makes cheaper versions of those tubes that work but they ain’t cheap either.

For quite some time I was planning to buy the Kenko but one day something got me thinking. Sometwhere deep in the back of my mind there was a thought that we have a 2x teleconverter bought on eBay about 2 years ago that we pretty much never use due to it’s lousy performance:

How about trying to take the glass elements out of it and use it as a macro extension tube?

Looking closer at the lens I noticed that the glass is held in the converter by small nut-like ring:

You can barely see on above picture. 10 seconds with screw driver and the glass elements (yes, there are three glass elements inside) were out:

The results? Working macro extension tube providing both electrical connection between body and lens as well as mechanical coupling for the aperture and auto focus. I tried it with our 18-200 zoom and here is one quick and dirty picture taken with the tube on:

This picture was taken from the distance about 5 inches from the ring. And imagine that – both autofocus and TTL worked as there was noting there.

There is only one slight problem with the extension tube – it’s quite thick, meaning that it’s a really macro-macro tube. But for $40 (that’s what I recall we paid for the converter we never used) you can’t really complain.