If you’re unfamiliar with extension tubes, they’re basically just hollow rings (containing no glass elements) that are placed between your lens and your camera. Why? Because the farther the physical distance is between your lens and camera sensor, the closer you will be able to focus on your subject – thus creating a higher magnification of the subject and mimicking the function of a macro lens, but at a considerably lower cost. The images above are the extension tubes I use with my Nikon lenses. It came as a set of three tubes in various lengths: small (12mm), medium (20mm) and large (36mm). They retail for just under $80. The longer the length, the higher the magnification. The tubes can be used individually, as seen in the photo on the left, or stacked together for maximum magnification. These tubes are made by Vello and are specifically designed to work with Nikon lenses. Vello also makes tubes for Canon and Fijifilm lenses as well. There are other manufacturers of extension tubes that are designed to work with other lenses. But whichever tubes you use, make sure that they’re equipped with contact points to maintain the communication between your lens and your camera – allowing for continued auto focus and auto exposure capabilities.
Downsides of Extension Tubes
As great as extension tubes are, it’s important to know that there no “free lunches.” Some light loss will be experienced when using them. This problem is exacerbated as you stack more tubes together. Whenever I stack all three, the light falloff is greater and vignetting (the darkening of the corners of the frame) becomes extremely noticeable. Even though I set my camera’s Vignette Control to “High,” I still can’t remove all of it. However, these issues are easily fixed. If necessary, I can raise my ISO to counteract the light loss, and I can crop out the vignette in post.
There seems to be some disagreement as to the resolution of images taken with extension tubes. I’ve read articles expressing conflicting views. But, since they don’t have any internal glass elements, which could degrade an image, the general consensus is that the resolution of an image taken with an extension tube is directly comparable to the resolution of the lens to which it’s attached. Personally, I’ve never experienced any problems with resolution.