Tech Tuesdays - Extension Tubes

Sometimes you need to get a little closer to an object than your lens will allow. We've all been there: You want to take a nice photo of a flower, but your lens won't focus any closer than 3 feet away, so the close-up you were trying to get isn't possible with that lens. Or is it?

If you had an extension tube in your bag, it might be possible. An extension tube is just a tube that fits between your camera and your lens. Some are made to retain autofocus and metering capabilities. Other, older models turn the most modern, expensive lens you own into a non-metering, non-AF'ing lens. In reality, that's not really a problem as you will probably be shooting a still subject and have your camera on a tripod.

The extension tube I own is the Nikkor M2. This tube came as an accessory to the 55mm Micro-Nikkor f/3.5 lens. By itself, the lens can reproduce a subject up to a 1:2 ratio. With the extension tube, the reproduction starts at 1:2 and goes to 1:1, a true macro. The M2 fits any Nikon lens, but it does not retain any metering or AF. I decided to give it a shot on a few different lenses that I own to see what kind of a difference it makes.

First, I tried it on my 50mm f/1.4 AF. This is an older lens that still has the aperture ring on the lens. Once the extension tube is put on, the camera can't control the lens, so fortunately I was able to manually choose my aperture. Without the tube, my minimum focusing distance was 14". When I put the tube on, I was able to focus from 3" away. You can see, I was able to get much closer to the pencil and get more detail. One thing I will note is that both of these were shot at f/1.4. When you put on the extension tube, your DOF dramatically decreases, so focusing accurately with such a large aperture is very difficult.




Next, I tried my 55-200mm VR lens at 200mm. This lens' aperture is completely controlled by the camera. For my initial shot without the tube, I shot at f/5.6 and my minimum focusing distance was 36". Once I put the tube on, I was able to focus from 24" away but the lens defaulted to it's smallest aperture, f/32. This was not very convenient, as I had to do a super-long exposure. I doubt this option would ever be convenient enough to be effective.




Finally, I tried the lens the extension tube was made for, the 55mm Micro-Nikkor. I set it at f/3.5 and was able to focus on the pencil from 5" away. Once I put the tube on, though, I was able to focus from only 2" away. You can see just how close I was able to get.




An extension tube can really change things up for the way you shoot. It can allow you to focus closer than you typically could with any given lens. It can decrease your depth-of-field. It can also disable any fancy features your lens might have, as well as taking away a few stops of light. Ultimately, if you need to be able to focus closer to an object and are working with a tripod, there's no reason not to have an extension tube at your disposal!