When you aim to photograph a subject up close, a macro lens is perfect. Many macro lenses only give you a 1:1 magnification ration. But if you need more than that?
This is where extension tubes come into play. They extend that limit extensively, allowing macro and close-up photography.
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What Are Extension Tubes
We use the word extension in photography to describe distance. It represents how far forward you can move the front element of your lens.
Why is this important? Well, the longer your lens, the closer your lens can focus on your subject.
Lens extension tubes extend the length of your lenses. They are hollow tubes, and are a great addition to any macro photographers kit.
NB: They are not to be confused with teleconverter lenses, which extend lenses. These are for increasing the focal length of a lens and not for macro photography. Both look very similar.
You can tell the difference easily. Lens extension tubes have a mm value, like a lens, such as 12 mm. Teleconverters will have a magnification value, such as x2.
These fit in-between your camera body and lens. They screw into your camera like a normal lens would, and then the lens screws into the other end.
By moving your lens further from your camera body, you move the front element closer to the subject. The closer you can focus, the greater the magnification.
These are what you would use to get past that 1:1 ratio that has been holding you back.
You can find your lenses’ magnification on the manufacturer’s website and specification pages. Once you have that, you are ready to calculate.
New magnification = Native lens magnification + (extension amount/focal length)
Example 1: The Canon 50mm f/1.8 STM has a magnification of 0.21x. If we use a 12mm extension tube on it, our new magnification will be 0.21 + (12/50) = 0.45x
Example 2: Using the same Canon 50mm lens with stacked 12mm and 25mm extension tubes would give us a magnification of 0.21 + ((12+25)/50) = 0.95x
The 0.95x magnification is almost the life-sized ratio of 1:1. Now, your Canon 50mm lens is a macro lens.
How to Use Extension Tubes
Lens extension tubes get you closer to your subject. Plain and simple. By using extension tubes, you get closer than you would be able to with close-up lenses.
Close-up photography isn’t quite macro, but allows you to get closer to a subject than you would normally do with standard lenses.
There are two different kinds of extension tubes.
Extension Tubes Without Electrical Contacts
These are the least expensive extension tubes. They are cheaper as they do not maintain that electrical contact between your camera and lenses.
This isn’t necessarily a problem. Set your camera to aperture priority or program mode.
Here, the biggest drawback is control over aperture. This is especially true if your lenses do not have manual aperture rings (the camera controls the aperture setting).
The lens will remain locked open at its widest setting, giving you a very shallow depth of field. You can capture close-up photographs this way, but you may need to use focus stacking.
If you DO have a lens with manual aperture rings, you can stop down manually. The viewfinder will get darker as you do this, making it darker to focus.
For extension tubes without electrical contacts, we recommend the Fotodiox Canon EOS Macro Extension Tube Set.
Nikon, Canon and Olympus all make OEM extension tubes. Sony does not. You can buy third-party tubes, such as Vivitar or Kenko. Pentax has extension tubes, but they cost more than a macro lens.
With Electrical Contacts
There are two different types of extension tubes with electric contacts. There are OEM (Original Equipment Manufacturer) and Third-Party with Autofocus.
They are basically the same thing, except the price of the OEM extension tubes could be more than 2x the price of the third party versions.
There is nothing very special about these extenders. There are no moving parts, or glass. Third-parties can make products that are just as good as the OEM versions.
They both maintain the communication between the camera and the lens. The camera controls the aperture settings. You can use any automatic exposure mode and still autofocus.
For OEM extension tubes, we recommend the EF 25 II and EF 12 II for Canon and the PK-13 Ai and PK 11A for Nikon. For third party products, you can’t go wrong with Kenko extension tubes for Canon and Nikon.
Advantages of Extension Tubes
Extension tubes are much cheaper than dedicated macro lenses. The whole point of them is to change the short or medium lenses you already own into producing life sized images.
There are usually three different lenses you can use, such as the 12mm, 20mm and 36mm. Combined they give you 32mm or 56mm with two or 68mm with all three.
Disadvantages of Extension Tubes
For this macro and close-up photography, extension tubes are less effective with telephoto lenses. This is mainly down to the fact that they have a very long minimum focusing distance.
By using lens extension tubes, you trade magnification for light. You can enlarge your images, yet there is less light present in the final scene. This is due to the light having to travel further to reach the sensor.
You might be able to account for this by using a wider aperture or a ring flash. It is also possible to raise your shutter speed or ISO, but it may affect your subject if they are moving.
How and When to Use Lens Extension Tubes
The best way to use these lens extension tubes is to use manual focus. Do this by using the manual focus ring on your lens to focus on the subject.
Your depth of field will be very shallow at this range. Raise your ISO to ensure you get a small enough aperture for adequate depth-of-field.
You can use a tripod for long shutter speeds if your subject is still. This wont work for moving subjects, such as insects.
For handheld macro photography, you will need a fast shutter speed to counter act camera shake. You’ll notice that the the extra magnification increases camera shake. Shutter speeds of over 1/250 are ideal.
And that’s it. A simple way to improve your macro and close-up photography. Now head out there and take some photos!
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