Archive for July, 2011
The ability to take super-close-up images opens a whole new aspect of photography, but true macro lenses can cost a fortune. Luckily, there are a couple of much cheaper solutions, and in this article I’m going to take you through one of them – reversing rings.
As the name suggests, a reversing ring allows you to attach a lens to your camera backwards. This allows you to get extremely close to your subject. The wider the angle of the lens, the greater the magnification: a 50mm lens will provide a rough 1:1 ratio, which is the benchmark of a ‘true macro’ lens. A 20mm lens will yield a massive 4:1 ratio. So if you’ve got an otherwise ordinary 18-55mm kit lens, you’re sitting on a great macro lens; it just needs a little help from a reversing ring! Because the ring attaches to the filter thread, you can even use them on lenses that have broken mounts: not an uncommon problem with cheaper, plastic kit lens mounts.
It’s not all good news though. Reversing rings come with a couple of small problems. Firstly, when you turn the lens around you obviously lose the CPU connection between the lens and the camera, so say goodbye to autofocus, metering (in most cases) and aperture control (though I’ll come back to that). Secondly, you expose the rear element of the lens to the outside world. Indoors this isn’t a huge issue, but it’s worth being aware of when you’re outside on a windy day or in other adverse conditions.
So, if you don’t mind risking a little dirt on your lens, or doing things manually, you can get into macro photography cheaply and easily. Let’s look into it in more detail.
To start, you’ll firstly need a camera and at least one lens. As I mentioned above, a wide-angle lens is ideal. It doesn’t matter if it’s a zoom or prime, but zooms give you some flexibility – more on that later.
I use two lenses in conjunction with my reversing ring – my Nikon 18-55mm kit, and a 40 year old Mitakon 50mm 1.7 PK mount lens. The advantage of this old lens is that it has a manual aperture ring, which neatly neutralises the loss of automatic control mentioned above. Also note that because I reverse the lens, it doesn’t matter that the lens mount is different from the camera’s. You can pick up this kind of lens (not to mention the cameras that go with it) for next to nothing. In general, I use the 50mm for subjects such as flowers where I don’t want to be super-close up, and the 18-55mm for insects etc.
Then of course, you’ll need a reversing ring. They’re available from most camera shops, both online and in the real world, and only cost about $15/£12/€14. The ring consists of a lens mount on one side (which should obviously fit your camera) and a male filter thread on the other; this should match the filter thread of the lens(es) you intend to use. Here’s my Nikon mount 52mm reversing ring, thread-side up:
The first thing to do is attach the ring to the lens by simply screwing it on like a filter. Then attach the lens to the camera as usual via the ring. Now it’s time a for a little light hacking. As I mentioned before, you lose aperture control when you reverse a lens. However, you may still need a wide-open aperture to get the most light into your camera.There still exists the normal trade off between DoF and aperture – so stopping down some may be an option for you to get more DoF (especially on fast primes like 1.8 or 1.4) at the expense of a dim viewfinder and slower shutter speed.. If you have an old manual lens like mine, great – just open that aperture up and go for it. But if you only have modern lenses, you need a hack.
Nikon, Pentax and Sony lenses
If you have any of the above lenses, you need an additional piece of highly specialised kit – a ball of poster tack. Next to the rear glass element of the lens is a small metal rectangular tab – this is the aperture lever:
Simply actuate the lever so the aperture is fully open (or any intermediate position you’d like), then carefully stick it in place with the poster tack. Don’t jam it right in: you don’t want to get bits in the mechanism. Just gently push it over so that it holds the lever in place.
Be aware that sometimes the lever can slowly push through the tack – if you notice the viewfinder darkening, check the lever.
Canon lenses lack an external aperture lever, but if your camera has DoF preview you can still make use of a reversing ring thanks to a little hack. In fact, modern Canon lenses default to wide open when off the camera, so you’ll only need to follow these instructions to stop down any. Mount the lens as normal and set the aperture wide open (or however you want it, in fact). Now press and hold the DoF preview button and while holding it in, remove the lens. The lens should ‘remember’ the aperture setting. To minimise the time you have the lens off and the camera body exposed, mount the reversing ring first, then do the hack and simply flip the lens over and remount it in reverse.
So now your lens is reversed and your aperture is as good as it’s going to get. Time to turn the camera on! Most cameras will probably start complaining that there’s no lens attached. Don’t worry, just flip to Manual mode. Now find a subject and frame it up in the viewfinder. What’s that? You just get a blur? That’s because you have to get really, really close: at 18mm you need to get within about 5cm/2” of the subject. So get stuck in.
Remember how I said zooms offer flexibility? Here’s where it comes into play. You can adjust the zoom to adjust the magnification, as in normal photography. But as focusing when a lens is reversed is achieved purely by moving the lens back and forth, the zoom acts as a focus too! So, if you’ve got yourself set nicely for a good shot of, say, a flower, but it’s just out of focus, simply adjust the zoom slightly to bring it in.
The next thing you’ll notice is that the depth of field is wafer-thin. That’s an issue with all macro photography – it’s a blessing and a curse, as it gives a nice blurred background that emphasises your subject, but it can also mean that not enough of your subject is in focus. Couple that with the fact that you’re focusing purely by moving back and forth (or breathing!) and you have a tricky situation. But the great advantage of digital photography is that you can take as many shots as you need to get things right, so, onwards and upwards.
Now, because you’ve lost metering, it’s time for some experimentation. You still have control of ISO and shutter speed, so first set the ISO to an appropriate level for the light. Now dial in a shutter speed, say 1/60, and take a shot. Have a look on your LCD – is the shot well exposed? If it’s not, adjust your shutter speed accordingly (faster if it’s over exposed, slower if under) and try again, repeating until you’ve narrowed down the right setting. If you’re having to set a really slow shutter speed, up your ISO to compensate. You can also use your on-camera flash, but you will need to turn TTL off and use manual firing.
If you’re planning on taking shots of fast-moving critters like insects, it’s a good idea to take a few test shots of a flower or other object, just to get the exposure in the right ballpark, so it’s quicker to adjust when the time comes. After a while, you’ll begin to get a feel for what settings work in a given situation, so that you’re closer to the right ones straight away.
And that’s really all there is to it. Here’s a quick checklist of things to remember:
- Attach the reversing ring and open the aperture using the appropriate method for your lens before attaching it to your camera.
- Set the camera to Manual mode before trying to take a shot.
- Get close to your subject and remember that you focus by moving the lens/camera/yourself back and forth.
- Experiment with shutter speed and ISO to get the correct exposure.