All lenses have a limit on how close they can focus. This is because as objects move closer to the lens, the focal point moves further back, eventually beyond the plane of the film or sensor. An obvious way around this problem is to move the lens further away from the camera. That’s what macro extension tubes do.
For those who cannot afford a dedicated macro lens there are other options, just as good, but that require a little patience, for macro photography.
Extension Tubes or a Reverse lens ring.
The macro extension tubes that I use are very cheap and simple. As you can see from the second photo, it comes in five sections. At each end is a bayonet ring for mounting the tube to the lens and camera body (in this case Nikon). In between those any combination of three threaded tubes of varying length can be used to change the extension by varying degrees. That’s all there is to these tubes, nothing more.
Pros and cons
Here’s the costs/benefits of tubes like mine:
-You need to manual focus, my moving the lens/camera closer or nearer to the object, the same result is achieved by moving the object you are taking a photo of.
-You have no auto control on the camera, you need to put it in Manual to be able to take any photos. You have no aperture on some lenses, the 50mm on the other hand is great for macros as it allows you to change the aperture manually on the lens.
-You could overtighten the threads on the extension tubes making them difficult to unscrew.
-You need to be careful with the lens on a tripod as the centre of gravity changes putting greater stress on the cameras body´s lens mount.
-You need plenty of light. As the objects are closer to the lens, the light is blocked by the lens, so you need a side, overhead, backlighting source of light. Not a problem in a studio of course.
-As there is no data connection between the camera and the lens so the EXIF data will not be complete.
-Photographic opportunities otherwise unavailable (without very expensive specialist lenses) are possible.
-Economical. I got mine from Amazon.com
– They have them for various makes of camera. There are others that cost more. Kenko for example.
-A light and compact addition to your gear. I carry mine with me everywhere.
-Useful even with telephoto lenses. A long lens is great for making things bigger, but they can’t focus very close at all. An extension tube can allow you to enlarge with the telephoto but still maintain a good working distance.
-Mechanically simple. There’s not much that can go wrong with these.
-They’ll get you thinking about new ways to take photos. Extension tubes make your lenses a whole lot more flexible, and don’t just have to be for photos of insects or flowers.
A macro reverse ring.
You need to make sure to buy one the correct size for your lens. I have two one for 67mm and one for 52mm.
The reverse ring focuses closer than the extension tubes. And they work like this:
Take the lens off the camera, place the reverse ring onto the camera in the same way as you would attach a lens, turn the lens around, back to front and attach to the reverse ring. You attach the side that the filter goes.
The strengths and weaknesses match above, but with the lens in the reverse position you need to take care of the electronics of the lens against damage.
A tripod is highly recommended.
The extensions tubes and reverse ring have opened up a whole new world for my photography without the expensive of a dedicated macro lens. They are great fun.