One of the questions I get asked a lot, is “Are extension tubes as good as a macro lens?”
And the answer really depends on what you want to achieve with your macro photography.
In the following article, I’ll go through exactly what an extension tube is, how it works and whether they’re suitable for you.
What is an extension tube?
Simply put, it’s a non-optical cylinder that you connect between the lens mount on your camera, and the mount on your lens.
The extension tube then moves the lens elements away from the camera body. This increases the image magnification on the sensor.
The image below shows how the object is reproduced on the sensor when the lens is connected directly to the camera.
In the following image, you can see that because the extension tube has moved the lens away from the camera body, the image is reproduced much bigger on the sensor.
The further the lens is from the sensor, the more magnification it produces.
What size would I need?
Different manufacturers produce different sizes. The most common sets usually contain sizes around, 12mm, 20mm and 35mm.
You can use as many, or as few as you want at the same time, to give you different magnifications.
There are two types of extension tube
If you’re looking to buy a set of extension tubes for your camera, be aware that there are two different types.
Which type you decide to buy will depend on the lens you’re going to use with them.
Those with electronic control
If you’re going to be using an autofocus lens, or a lens with an aperture adjustment that’s controlled in-camera, you’ll need extension tubes that have electrical contacts.
These contacts allow your camera to control the lens in the same way it would, if it was connected directly to the camera.
Autofocus will still work. Light metering will still work and you’ll still be able to use your camera to make adjustments to aperture, etc.
Bare-bones extension tubes
There are dozens of different manufacturers that make extension tubes without electrical contacts.
These work in the same way (they move the lens elements away from the sensor), but you can’t control the lens with the camera body.
If you’ve got a lens with an aperture ring, and with manual focus, this type will work just as well.
You’ll just need to adjust the aperture on the lens, then the camera will meter correctly for the shutter speed and ISO.
Obviously, with no electrical connection to the camera, you’ll have to focus manually as well.
Does it matter who makes the extension tube?
Extension tubes are readily available for most makes of camera. And as with most things, you can find extension tubes that range from very cheap, to very expensive.
If you can’t find extension tubes direct from your camera manufacturer, there are a couple of third-party manufacturers that I recommend. Both of these will provide great quality components.
Shop around though if you decide to try extension tubes. Prices can vary widely. Amazon is a good place to start.
What is the image quality like?
Because the extension tubes don’t contain any optics, the image quality isn’t affected. All they do is move the lens optics further from the sensor.
The main issue is that if you’re using extension tubes, the amount of light that reaches the sensor can be reduced, because it has further to travel. But a small amount of exposure compensation usually puts that right.
So, the quality of your image, is the same as it would be without the extension tubes in place.
Examples of images taken with extension tubes
The following images were all taken with standard lenses and extension tubes. Most of them taken with 1, or 2 extension tubes. The sea salt crystal was taken using 150mm of extension tubes.
I’m going to finish with some pros and cons.
Extension tube Pros
- Extension tubes provide a reasonable increase in magnification with any camera lens.
- Extension tubes are much less expensive than a dedicated macro lens and for the most part, work just as well.
- You can use various sizes of extension tube at the same time, giving you different magnifications.
- It doesn’t have an optical element, so there’s no deterioration in image quality.
- If you use an extension tube with electrical contacts, you still have autofocus, etc.
Extension tube Cons
- It causes your lens to focus more closely than it was designed to. This means you can only achieve focus within a small area. You lose infinity focus.
- Macro lenses generally have wider apertures than standard lenses.
- Macro lenses are generally sharper than standard lenses.
- Macro lenses can be used as standard lenses as well. They focus to infinity.
- The amount of light getting to the sensor is reduced with extension tubes.
I hope this article has answered some of your concerns. If you’ve still got a question, please let me know in the comments below and I’ll do my best to answer.
Until next time, stay sharp!