In this post I’ll discuss an easy and cost effective way to get closer to your subject using one of the most versatile pieces of close up equipment called extension tubes. Eliot Porter was very well known for his intimate portraits of nature, but Eliot’s quote about intimacy within the bigger picture definitely captures the attention of what all close-up or macro photographers strive for as well. “A detail is quite capable of eliciting a greater intensity of emotion than the whole scene evoked in the first place…because the whole of nature is too vast and too complex to grasp quickly, but a fragment is comprehensible and it allows the imagination to fill in the excluded setting.” Close-up photography allows us to go on a journey into another world we never see with just our naked eyes. To enter this “close-up” world we need to use some specialized equipment like a macro lens or some supplemental tools, because most standard fixed or zoom lenses physically can’t focus close enough. One of the easiest options (although “relatively” expensive) to achieve “up-close” photography is to purchase a “true” macro lens with prices ranging from $300 to $1,800. These lenses all have very fast apertures at f2.8, are super duper sharp (did I just say super duper?) and allow very close focusing to achieve a 1:1 magnification ratio or greater. Canon’s MP-E 65mm can achieve a 5:1 magnification ratio … Wow!
Before we go any further, a quick definition is needed. A 1:1 magnification ratio (MR) is defined by a side-by-side comparison of a subject’s physical size to its actual size in the image (on the sensor), and they would be the same. A great alternative to buying a macro lens is using extension tubes as a supplement. Extension tubes are relatively inexpensive, you don’t sacrifice image quality compared to using other supplements like close focus filters, telephoto-extenders or converters. The extension tubes are hollow, meaning no lens glass is involved in the design. They mount between the lens and the camera body and allow you to focus closer with any lens you own. Extension tubes are available individually or in a set of two to three different sizes (length) depending on the brand. The difference in size allows various distances of close focus ... more extension = closer focus. The more common sizes in a set of three are 12, 20 and 36mm.
*The only mild annoyances when using these tools is some light loss of up to two stops (if all the tubes are used at one time) and stability because the lens will be further from the camera body. So … keep it steady grasshopper. In my next blog two weeks from now I’ll discuss stability when shooting really close up. Canon, Nikon and other major brands make these, but they’re a little pricey (~ $100 each), not sold in sets, and since no glass is involved, not worth the dinero in my opinion. Save the $$$ for some other photo gadget you want or a nice meal out. Consider a third party manufacturer like Kenko ($130) or Vello ($80). I use the Vello extension tubes for Nikon. They are very well-made, tight, light and just right!
If you want to know the precise magnification ratios using extension tubes, use this simple equation: Magnification Ratio (MR) = Extension size / Focal length If you want a life size subject (1:1 MR) use 50mm of extension on a 50mm focal length. The sequence of shots below show a 50mm shot all at the minimum focusing distance with no extension, 12mm, 20mm, 36mm and 48mm of extension (approaching life size, right?). If you're still hungry, here's a little more food for thought. If you want 1/2 life size (1:2 MR), use 25mm extension on a 50mm focal length ... you get the point. If math wasn't your favorite subject growing up, the most important thing to know is that when you add a bigger extension tube with any focal length it allows you to focus even closer.