Simple tubes bring remarkable results.
Macro photography allows you to capture images of very small subjects, details or patterns. Unfortunately, macro lenses are expensive. In the previous two articles I explored inexpensive ways to do close-up photography without buying a new photographic lens. We looked at Inexpensive Close-Up Photography – close-up rings and Inexpensive Close-Up Photography – Reverse Rings.
Another way to do macro photography without a large investment is to use extension tubes.
Extension tubes are hollow metal rings that attach between your DSLR camera body and your lens, as shown in the image above. The further your lens is moved away from the digital image sensor
by extension tubes, the closer you can get to your photographic subject and the more the subject is enlarged.
Visualization of the effect of an extension tube.
The diagram shows in black the actual size of the image circle and the rectangular sensor size inside it. The red lines show how a 7 mm extension tube casts a larger image circle (red). The image sensor (black rectangle) records the enlarged section in the middle and ignores the rest of the circle outside the rectangle. •
The camera’s sensor is a rectangle, but your lens is round. When your camera records an image, it is only recording the rectangular portion of the light that falls on the sensor. This is indicated by the black rectangle (the sensor) and black circle (the image circle) in the diagram. An extension tube moves the lens further away from the sensor, which makes the image circle (red) larger. Now the sensor is recording an area less than a ninth of the original image (compare the black and red rectangles). The longer the extension tube, the further your lens is from the sensor and the more detail you are able to capture.
How to use extension tubes
There are two types of extension tubes. One type is a set of generic metal tubes, usually packaged as a set of three allowing you various enlargements.
The second type is also a tube but maintains the electrical connections between the camera and the lens. The latter allows you to use all the functions of your lens, including autofocus and aperture adjustment. These expensive versions are sold as one piece. You do not have the option to vary the enlargement factor. There is a big difference in price between the two. You will pay around ten times as much to maintain those lens functions.
The directions below apply to the cheaper version of extension tubes.
The generic metal ring extension tubes are often sold in sets of three lengths with 7 mm, 14 mm, and 28 mm being common. In addition to the three rings, you will receive two additional pieces: a piece that mounts the extension tube to the camera body and a piece that mounts the lens to the extension tubes. You will need to buy a lens mount that fits your camera brand.
• Extension tube set •
A set of three extension tubes and mounting pieces. The camera mount piece (near end) and the 7 mm extension tube are already screwed together. The lens mounting piece is visible in the back.
Click image to view large
• Extension tube set • By ArchaeoFrog on Flickr
Decide which extension tube (or tubes) you want to use. Each length can be used independently or combined to create a longer extension (eg. closer images). Screw the extension tube(s) onto the camera mount and onto the lens mount. Then, you can screw the extension tubes onto the camera and screw the lens onto the extension tubes. There are red and white circles as indicators on the mounts to help you align them when attaching. To detach the lens, push down on the silver knob on the lens mounting piece and unscrew the lens. To detach the extension tubes, push the lens release button on your camera body. If you have trouble unscrewing the extension tubes from each other or from the mounts, wrap a rubber band around one section for increased grip.
• Views of the back of a penny (Cent). •
These four images were shot with a Canon 50 mm f/1.8 lens alone (top left), with a 7 mm extension tube (top right), with 7 mm and 14 mm extension tubes (bottom left) and with 7 mm, 14 mm, and 28 mm extension tubes (bottom right). Each image was cropped to a square but not resized
Click image to view large
• Views of the back of a penny (Cent). • By ArchaeoFrog on Flickr
Adjusting the aperture
The full functionality extension tubes connect directly to your camera body. Aperture settings are carried out as with any other ordinary photograph. The generic metal ring style requires a work-around to adjust the aperture. A detailed explanation of the process is available in the previous article: Inexpensive Close-Up Photography – Reverse Rings.
If you want to use an aperture other than the widest default of your lens, first dial in that aperture in aperture priority or manual mode. Then, depress and hold the depth of the field button while pressing the lens release button and removing the lens. (Please note: not all DSLR cameras have a depth of field preview button.) Next mount the extension tubes to the camera and the lens to the extension tubes, and the lens will maintain the chosen aperture until reconnected directly with the camera body. I suggest you only do this where you can avoid getting dust or debris entering the camera body.
• Detailed rose •
This rose was shot with a Canon 50 mm f/1.8 lens and a 7 mm extension tube. The aperture was set at f/22, resulting in a shutter speed of 30 seconds at ISO 100. A tripod was used.
Click image to view large
• Detailed rose • By ArchaeoFrog on Flickr
Advantages and limitations of extension tubes
Extension tubes are a versatile and simple way to achieve macro or close-up results. The generic metal ring style is very inexpensive. The pricier full-function tubes gives you full control over your camera for less than a dedicated macro lens. Both styles are small and portable. However, the generic tube-sets give you three tube lengths to achieve a variety of enlargement factors which is more flexible.
If you choose the cheaper extension tubes, you will lose autofocus. Manual focusing often results in better images in close-up photography. Manual focus need not be intimidating. A little practice will make you quite accurate especially with a tripod.
Using an extension tube does change the minimum focusing distance of your lens and requires you to be physically close to the objects you are photographing. If you put too many extension tubes together on a long zoom lens, you may find than an object would have to actually be located somewhere inside your lens to be in focus. I cannot put all three tubes together on my Tamron 18-270 mm at 270 mm for this reason. All three tubes can be used on my 50 mm lens, however, to give a reasonable working distance of a few inches The image below is taken with this configuration. This makes extension tubes ideal for flowers, indoor shots, or other immobile subjects or details.
• Extension tubes in action •
In this image, I am using a Canon 50 mm f/1.8 lens with the 7 mm, 14 mm, and 28 mm extension tubes to photograph the penny (one Cent piece) seen previously.
Strong lighting is a benefit to all macro and close-up photography. As the lens moves further from the camera, the area being captured becomes smaller, and the amount of light reaching the sensor becomes less. Strong indoor lighting or bright, natural daylight can provide enough light for you to maintain a reasonable shutter speed, even when hand-held. Better results are achieved by using a tripod. Then you can use longer shutter speeds to brighten the image.
Flexibility and price win the day
Extension tubes are an excellent way to try close-up or macro photography with your existing lenses. The inexpensive generic tubes give great results. You also receive a variety of widths to broaden the scope of how close or how far you can get to your subject and what level of detail you can achieve. On balance the generic metal tubes will provide you with a full macro experience, with flexibility and at a reasonable price. Everyone will find them affordable and they will get you started. Try them for yourself and then decide if you want to upgrade to the fully-functional tube version or a full macro lens.
The generic extension tubes can purchased from Amazon. This extension tube search provides most of the options…
Extension tube list for various camera brands
A range of 50mm lenses – great for working with macro extension tubes
Articles on close up and macro photography
By Katie McEnaney
Part 1 of this series focused on using close-up lenses, and Part 2 covered reversing lenses using reversing rings. Part 4 will bring all these techniques together with a range of close-up ideas and tips.
Inexpensive Close-Up Photography – close-up rings
Inexpensive Close-Up Photography – Reverse Rings
Inexpensive Close-Up Photography – Extension Tubes (this article)
Inexpensive Close-Up Photography – Tips and Tricks
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