Thursday, 25 April 2013

Macro Photography for under $10

Macro Photography for under $10

To take super-close-up images opens a whole new aspect of photography, but macro lenses can cost a fortune. Luckily, there are a couple of much cheaper alternatives on offer, and in this blog/video I’m going to take you through three of them.

Here is the test image using the standard kit lens 18-55mm this was set to the full 55mm

Macro Extension Tubes
The tube contains no optical elements; its sole purpose is to move the lens farther from the image sensor. The farther away the lens is, the closer the focus, the greater the magnification, and also the greater the loss of light. Lenses focus closer than infinity by moving all optical elements farther from the sensor; an extension tube simply imposes this movement.
Extension tubes without electrical contacts will not allow an electronic automatic camera to control the lens, thus disabling autofocus and in some cases forcing a user to shoot wide open unless the lens offers manual aperture control. More expensive extension tubes contain electrical contacts allowing the user to use autofocus and electronically control the aperture of the attached lens. Other items like lens adapters may unintentionally have an effect similar to an extension tube.

Kit lens 18-55mm set to the 55mm end using all the tubes

Macro Screw Filters
A close-up filter is a lens that attaches onto the end of a camera lens via a screw thread. The purpose of the filter is to decrease the minimum distance that a lens requires to focus. For example most telephoto lenses need the subject to be at least a metre and a half away before they can focus. By attaching a close-up filter to the lens you can reduce this to maybe 0.75 metres.
Close-up filters are measured in Dioptre, with +2 being weak and +10 being strong. A dioptre is a measure of lens power.
Kit lens 18-55mm set to the 55mm end using all the filters = +17

Filters can be “stacked” together (one filter screwed onto the lens and another screwed into the first filter). When stacking filters always make sure that the strongest filter is closest to the lens.

Macro Reverse Ring
Cost about $8. 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 you intend to use.
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.

Kit lens 18-55mm set to the 55mm end using reverse ring adapter

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. Secondly you expose the rear element of the lens to the outside world. Indoors this isn'ta 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. The advantage of this old lens is that it has a manual aperture ring, which neatly neutralises the loss of automatic control mentioned above.
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.
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.

Here are all the test images side by side

Image1 Kit lens set to 55mm. 
Image 2 Extension Tubes.
Image3 Kit lens set to 55mm with all Filters +17. 
Image4 Reverse Ring Adapter.


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