Many people consider ‘true’ macro photography to be a 1:1 reproduction of the subject, i.e. the image produced on the sensor is the same size as the actual subject, which is different to close up photography. Macro and close up photography is niche and not for everyone, however it is something all photographers should try at some point to see if it is their bag.
In order to get the 1:1 reproductions it is possible to buy specially designed macro lenses, such as the Canon EF100m f/2.8 macro USM, although these are quite expensive and many people are not prepared on shelling out a few hundred pounds (or dollars) to see if macro and close up photography is for them. Fortunately, there is a cheaper alternative available.
For those wishing to try their hand at close up and macro photography a cheaper alternative is to use extension tubes which in a nut shell are hollow plastic tubes that are put between the lens and the camera body. Extension tubes contain no optics whatsoever, and by increasing the distance between the lens and the sensor the camera is forced to focus closer to the subject, creating a macro and close up type effect. Extension tubes can be used with all lenses, therefore they are suitable for everyone.
Most modern digital SLR camera lenses contain autofocus technology, which in order to work requires the electrical contacts on the lens to be in contact with the electrical contacts on the camera body, therefore sticking a plastic tube, i.e. the extension tube, between the lens and the camera body may create a problem with the autofocus system. Fortunately, some extension tubes, such as those made by Canon and Kenko, have got the electrical contacts to preserve the autofocus feature however some extension tubes do not. This is worth bearing in mind before purchasing some extension tubes, although if you are comfortable using manual focus using extension tubes with no electrical contacts should not present any problems. As you’d expect, the extension tubes with the electrical contacts that preserve autofocus are more expensive than those that do not. Many photographers prefer to use manual focus when taking close up and macro shots because of the shallow depth of field.
As well as autofocus most modern day lenses allow the photographer to the aperture, and this is also achieved through the electrical contacts. Whilst many photographers will be willing to lose the autofocus feature it is unlikely they will be prepared to lose the ability to change the aperture of the lens. Using extension tubes that do not have the electrical contacts means the lens will be wide open which is likely to lead to an unacceptable depth of field and blurred images. Very few lenses are sharp when wide open therefore using extension tubes that do not allow the aperture to be varied means the lens will not be at its sharpest.
When using extension tubes without the electrical contacts there is a way of fooling the camera in to retaining a chosen aperture setting but this is fiddly and time consuming. The process involves putting the camera in to aperture priority mode and setting it to the required setting. By holding down the depth of field button, removing the lens and then inserting the extension tube before putting the lens back on, all whilst holding down the depth of field button, the camera will retain the aperture set. Sounds a bit of a pain right? Well, it is.
As the process is so long winded and cumbersome there is the added problem the shot may be missed. For example, if the subject is a bug by the time the camera and extension tube has been set up the subject may well have crawled away or flown off, however you shouldn’t have any issues if photographing still life, insects or flowers.
Removing the lens over and over again to change the aperture setting increases the chance of dust and debris getting on to the sensor, which may cause problems. In addition, the lens fitting is likely to get worn out quicker and there is an increased chance of damage to both the camera body and the lens, which could prove to be very costly.
There is no doubt about it, extension tubes are a great way of getting in to the world of close up photography, although it is unlikely you will get proper macro 1:1 reproduction. That said it is possible to get some very good images using extension tubes and a normal lens. Because of the all the issues associated with extension tubes that have no contacts, and the potential damage it could cause to the lens and camera body, which is likely to be quite costly, it is advisable to use the Canon or Kenko extension tubes with the electrical contacts. These are more expensive than those extension tubes without the electrical contacts but it is definitely worth spending a bit more. Now you have the best extension tubes