August 20th 2012 by Andrew S Gibson
EOS 5D Mark II, EF 40mm f2.8 STM pancake lens, EF 25 extension tube, 1/250 second @ f5.6, ISO 1600
Here are a few photos taken with Canon’s new EF 40mm f2.8 STM pancake lens and extension tubes (I touched on this briefly before here). The minimum focusing distance of this lens is only 30 cm, which means that it can focus quite closely to the subject without additional assistance. If you’re using this lens on an APS-C camera, where it is effectively a short telephoto, that will get you in fairly close. On a full-frame camera, less so.
Whichever camera you have, if you want to get up closer you need to use either a close-up filter or an extension tube. I prefer extension tubes as they are more effective with short focal length lenses than close-up filters. Canon makes two extension tubes, the EF 25 II and EF 12 II (I have the older EF 25 and EF 12 extension tubes which do exactly the same job except they only work with EF lenses – the newer models work with EF-S lenses too).
You can also buy extension tubes from Kenko and Vivitar. Like the Canon tubes, the electrical connection between the lens and the camera body is retained, so the camera can control exposure, the aperture setting and autofocus.
You can buy extension tubes from Amazon or eBay that are much cheaper, but with these you lose the electrical connection. That doesn’t affect auto-exposure (just put the camera in Program or Aperture Priority mode) but it does mean that you can’t stop the lens down and can only work at its widest aperture. Considering that you often need to stop down to increase depth-of-field with close-up photography, this is a serious limitation. But they will get you started if you’re on a tight budget.
Extension tubes work by fitting between the lens and the camera body. This pushes the front element of the lens further from the camera body, in turn reducing the minimum focusing distance of the lens so that you can get closer to the subject and obtain more magnification.
The only drawback of adding extension tubes is that the effective aperture is reduced, so less light reaches the sensor. The camera’s autoexposure system takes care of this, so you don’t need to worry about exposure. But you will have to either raise the ISO or use a slower shutter speed at any given aperture to compensate for the light loss.
EOS 5D Mark II, EF 40mm f2.8 STM pancake lens, EF 12 extension tube, 1/1000 second @ f2.8, ISO 800
I took this photo with the 40mm pancake lens and the EF 12 extension tube. An aperture of f2.8 blurred the background – you can see the depth-of-field is very narrow.
EOS 5D Mark II, EF 40mm f2.8 STM pancake lens, EF 25 extension tube, 1/1500 second @ f2.8, ISO 800
This is the same flower, but taken with the EF 25 extension tube fitted. I was able to get much closer. This flower was small – it only three or four centimetres across.
EOS 5D Mark II, EF 40mm f2.8 STM pancake lens, EF 12 extension tube, 1/1000 second @ f2.8, ISO 400
This photo was taken with the 40mm lens and EF 12 extension tube. I liked the tattered petals.
EOS 5D Mark II, EF 40mm f2.8 STM pancake lens, EF 25 extension tube, 1/2000 second @ f2.8, ISO 800
And this one with the 40mm lens and EF 25 extension tube. I used f2.8 for both photos. This is a good example to show you how narrow the depth-of field is at f2.8 in close-up work.
If you’d like to learn more about Canon lenses, then take a look at my new eBook Understanding Lenses: Part I. If you want to learn more about close-up and macro photography, then you may like Up Close, available from Craft & Vision.