A Guide to Extension Tubes :: Digital Photo Secrets

A Guide to Extension Tubes

by David Peterson 1 comment

If you are anything like me, you often find yourself marveling at the beauty of macro photography. Dew drops on flower petals, butterfly wings and the inner workings of a pocket watch up close create a sense of wonder that can’t be found elsewhere. You've also probably lamented at the cost of a dedicated macro lens and have a hard time justifying the cost. Good news, there is an alternative called an extension tube.

An extension tube is a component that fits between your lens and your camera body. It looks like a lens, except its missing one typically important component, the glass. Don’t worry, it’s not a mistake. These hollow tubes, made of plastic or metal, are created for the purpose of moving your lens farther away from the internal sensor located inside your camera body. Doing this allows you to get closer to whatever you are photographing, increasing the magnification.

Types of Extension Tubes

There are two different types of extension tubes and neither are as technologically sophisticated as a macro lens. The first has no electric components. They are literally just a tube with connectors where you can attach the lens to one end and the extension tube lens combo to your camera body. This means you won’t be able to use the autofocus function, or control your aperture unless your lens has dedicated aperture rings. If it does, you will be able to control the aperture but the view through your viewfinder will darken and decrease as you close the aperture to extend your depth of focus.

The other kind of extension tube is one that contains the electrical components required to let your lens and your camera body talk to each other. They contain these electrical connections on both side of the tube and the electrical current will continue to move through them even if you stack them. That means you will still be able to use the camera's autofocus. These are also usually sturdier than the other kind and they are also more expensive.

If you plan to use these to do more than a couple of shoots, I recommend swinging for the electronic version. The off brands for Canon, Nikon and Sony start at about $20. Name brands start at about $200 for a single tube but don’t seem to add any additional quality or notable features. I would recommend finding an off brand with good reviews and trying it out. Kenko is highly regarded off brand amongst photographers. A set of three stackable extension tubes is about $200 and contains a 12mm tube, a 20mm tube, and a 36mm tube. Versions are available for Canon and Nikon cameras.

The Math

To figure out the magnification that is achieved by using an extension tube divide the combined length of your extension tubes in millimeters by your focal lens in millimeters. For example if you are shooting with an 85mm lens and have added a 25mm expansion tube, simply divide 25 by 85 for a magnification of x0.29.

While it’s nice to know how much magnification you’ll get from an extension tube, sometimes it is best to get a set and play around with it. It’s hard to imagine what a .29 magnification looks like without seeing it.

Step by Step

Setting your extension tubes up can be done in three easy steps.

  1. Turn off your camera and detach your lens from you camera body.
  2. Attach the extension tube(s) to the back of your lens where it would connect to your camera body
  3. Attach the extension tube where you would usually attach your lens and shoot.

The Pros and Cons of Extension Tubes

Pros:

  • Extension tubes are cheaper than a dedicated macro lens. Even if you spring for the brand name extension tubes, you will still save hundreds of dollars.
  • They are interchangeable so you can use them with multiple lenses and are stackable so you can expand to your heart’s desire.
    Extension tubes are only one of a few ways of to add magnification but it is the one that doesn’t add another piece of glass in front of your sensor. You don’t have to worry about the quality of the glass affecting the clarity of your photo.
  • The magnification allows you to maintain your pixel count because you don’t have to crop down to emulate a macro photography. You’ll actually be taking one.

Cons:

  • Extension tubes are better suited for use in conjunction with lenses with small or medium focal lengths. If you are hoping to extend the macro capabilities of your telephoto lenses, this isn’t the solution for you. They also work better with prime lenses than zoom lenses because it cuts down on human error.
  • There is a loss of light caused by extending the amount of space between the sensor and the opening at the end of your lens. This means you are either going to have to increase the ISO which introduces grain or open your aperture (smaller f-number) which decreases your depth of focus.
  • Autofocus is either impossible or unreliable and handshake is magnified. If you are shooting at a shutter speed less than 1/250th of a second you will need a tripod to steady your shot.

Remember:

Extension tubes are a great resource for those of us who desire to dabble in macro photography. They are an inexpensive introduction to what might be your next photographic passion because they are easy to use and modify. Those three steps will get you ready for your close up, your macro photography close us, that is.

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Comments

  1. ronald says:

    todays digital cameras wont work without the lens to the body have to screw in the lens. and wont work with another lens even though it fits.

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Difficulty:
Beginner
Length:
7 minutes
About David Peterson
David Peterson is the creator of Digital Photo Secrets, and the Photography Dash and loves teaching photography to fellow photographers all around the world. You can follow him on Twitter at @dphotosecrets or on Google+.