You don’t need a macro lens to enter the world of
larger-than-life photography. Attaching your lens in
reverse on the camera body is all it takes to enter a
world where tiny creatures barely visible to the naked
eye fill the frame.
Camera compatibility: all EOS cameras
In normal photography the subject is larger than the image on the sensor. In macro photography it’s the other way around – the subject is reproduced at life-size or greater on the camera’s sensor (or film).
One way to try out true macro photography is to buy Canon’s MP-E 65 lens. It’s the only Canon lens that offers magnifications from life-size to 5x life size in a single focusing action, but like all specialised lenses it comes at a price (rrp £1249.99).
However, there is an alternative that is much easier on the pocket – reverse lens macro. You may not even have to buy another lens to try it out. The idea, as the name suggests, is to turn your lens around and use it in reverse. It may sound strange at first, but in this position the lens acts like a high quality magnifying glass. The image quality with this technique can be very good, matching the performance of a specialist macro lens.
One way to approach reverse lens macro photography is to attach the lens directly to the camera using an adapter ring built specifically for this purpose. A good place to start is by using a 50mm lens or an EF-S 18-55mm kit lens. The combination of a 50mm lens and an EOS camera with an APS-C sensor gives you near life-size reproduction, matching the magnification achieved by Canon’s EF 100mm and EF-S 60mm macro lenses. A wide-angle lens will get you even closer – when lenses are reversed shorter focal lengths give you greater magnification than longer ones.
The only drawback is that there is no Canon-approved method of stopping down the aperture if you are reversing an EF or EF-S lens directly on the camera. This means that you have to take photos at the maximum aperture of the lens where the depth-of-field is very narrow. Don’t let this put you off trying this technique, though, as you can still get some beautiful photos this way.
To fulfil the potential of this technique you really need to find an approved method of stopping down the reversed lens. One solution is to use an old Canon FD lens (these have an aperture ring on the lens). You can also use lenses from other manufacturers – many lenses from old film cameras have lenses with a ring which alters the aperture. We’ve even heard of enlarging lenses being used this way.
Setting the aperture of EF and EF-S lenses
To stop down off-camera EF and EF-S lenses put the lens on a camera body the correct way around and set the aperture in Av mode. Press the depth-of-field preview button. The iris inside the lens closes down. Remove the lens from the camera with the depth-of-field preview button held down – the iris remains closed. You can reverse mount the lens and use it at this aperture. It goes back to normal when you remount the lens the right way round.
The problem with this technique is that the camera has to be switched on when you remove the lens – and electrical charges on the sensor can attract dust. Canon recommends that you don’t use this method. It’s your call. The technique gives more creative control over your reversed lens images at no immediate cost, but you might need to spend more on sensor cleaning.
How it works
These diagrams show how reverse lens macro photography works. With a lens mounted on a camera in the normal position (below top), the image of a large object is reduced in size so that it can be recorded on the sensor or film. When the lens is mounted in reverse (below bottom), the opposite happens. Small objects are recorded at life-size or enlarged – a 50mm lens reverse mounted on a body with an APS-C size sensor achieves near life-size reproduction.
The image quality is good. In normal photography, the distance between the front of the lens and subject is greater than the distance between the rear of the lens and the image. With the lens reversed and the subject much closer, the rear of the lens (now facing forward) is still dealing with shorter distances than the front of the lens (now facing backwards). The lens design is optimised for these conditions. Reversing the lens maintains these conditions with the subject closer to the lens than the image.
A reversed lens, unless you use the Novaflex EOS Retro (below), has no electrical connection with the camera. However, the camera can cope with this quite easily. Instead of an aperture setting, you’ll see the figures ‘00’ in the camera’s viewfinder (or the LCD screen). This indicates that the camera is unable to communicate with the lens.
In this situation the camera calculates exposure according to how much light is coming through the lens. If you are using a reversed lens with a manual aperture ring, you can set the aperture to any setting you like. The viewfinder goes darker, making it more difficult to see, but the camera still works out the exposure.
The easiest exposure mode to use is aperture-priority (Av). All you have to do is set the ISO and the camera calculates the shutter speed required. Program (P) mode also works well. In both of these modes you can use exposure compensation to override the camera’s settings if necessary.
Avoid the basic zone macro mode. The camera takes control away from you by changing the ISO setting and activating the built-in flash if it thinks light levels are too low.
Focusing is tricky at high magnifications. The slightest subject or camera movement will move the point-of-focus. One way to deal with this is to mount the camera securely on a tripod, set the focusing ring to infinity, then move the subject, rather than the tripod, backwards or forwards until it is in focus.
Another option is to buy a focusing rail – this device lets you move your camera backwards or forwards along a metal rail, giving you precision control over focusing.
If your camera has Live View, use it to focus accurately. With Live View you can zoom in to see the image at up to 10x magnification giving much greater control than that offered by the viewfinder image.
Full frame cameras
If you have two lenses coupled together and the primary lens is too short, your images will suffer from vignetting. Vignetting is more likely with a full-frame camera than on a camera with a smaller sensor.
You can reduce vignetting by stopping down or by using an extension tube between the primary lens and the camera body. The extension tube pushes the primary lens away from the camera, thereby extending the size of its image circle.
Two reversing rings
Above A reversing ring has a lens mount on one end. This attaches to the camera lens mount. At the other end is a thread which screws into the filter mount of the reversed lens. Reversing rings are available with different sizes of thread to suit a variety of filter mounts.
Above A coupling ring has threads on both ends so that two lenses can be joined together at their filter mounts. One lens is attached to the camera body, leaving the other lens in reverse on the first. Coupling rings can be combined with stepping rings to fit lenses of different diameters together.
When using a lens reversing ring we recommend screwing it into the filter thread of the lens first, then attaching the ring to the camera.
Read the rest of this article in the July-September 2011 back issue of EOS magazine. Available as print and digital edition.
In a range of different filter sizes to fit your lens. Enables you to mount your lens in reverse onto your EOS camera.
Stack your lenses for an even closer shot of your subject. Sizes to fit a range of lenses. Enables you to couple one lens in reverse to a second lens.
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