Macro Photography with Cheap eBay Extension Tubes
If you are looking at exploring macro photography, there are a number of options available.
- Dedicated Macro Lens - can be an expensive option but will provide the most flexible solution. A Macro lens has been specifically design to provide a higher magnification and a closer focal point than normal prime or zoom lenses.
- Reversing the Lens - an adapter is available to allow a lens to be reversed onto the camera body. This will remove the automatic focus and aperture controls, but does offer a cheap solution, as cheap eBay adapters are available.
- Close-up Filters - similar to other lens filters in that they screw onto the end of your lens to provide reduced focal distance and magnification. You will need to ensure they match your filter size. Both Nikon and Canon offer close-up lens, as well as cheap eBay copies.
- Extension Tubes - extension tubes connect between the camera body and the lens, allowing you to focus at a much reduced distance and also increase the magnification factor of the lens. Available with electrical contacts for automatic focus and aperture, with the popular Kenko tubes up to 100 dollars each. Cheaper extension tubes are available that do not have electrical contacts, with cheap eBay tubes available for 10 dollars a set.
As a experiment, I decided to try out the cheap ten dollar eBay extension tubes. I was obviously not expecting much from them, but I was pleasantly surprised by the results I achieved.
I was planning on used them on my Nikon 50mm F1.8 prime lens, so chose the Nikon mount tubes. They are available for most of the popular SLR mount formats. The tubes are constructed of metal and come in 5 separate components. They can be quite hard to unscrew if you tighten them too much.
The set includes the following:
- Camera Body Mount Adapter
- Lens Mount Adapter
- 9mm Tube
- 16mm Tube
- 30mm Tube
The tubes can be stacked together to give a maximum length of 55mm. When you add a tube between your lens and the camera you are effectively adjusting the focal point of the lens, allowing the lens to focus closer which also increases the magnification factor of the lens. The standard Nikon 50mm lens can focus to 45cm. One of main differences between the cheap eBay extension tubes and the more expensive tubes (such as those from Kenko) is the lack of any electrical contacts between the camera body and the lens. This means that you will need to set both focus and aperture on the lens manually. The Nikon 50mm includes an aperture ring, which simply needs to be unlocked from its default F22 position. With lenses that do not include an aperture ring, things get a bit more tricky. You will need to attach the camera without the extension tubes, adjust the aperture (best in aperture priority or manual mode) and then use the depth-of-field preview button to stop-down the lens. You will then need to remove the lens keeping the lens stopped down (keeping the depth of field preview pressed.) Note that it is not recommended by camera and lens manufacturers to remove the lens when the camera still turned on, but I have not heard of any adverse effects of doing this. However, you are potentially putting your camera and lens at risk.
To test the effectiveness of the extension tubes, I chose the toy pencil sharpener from the long distance tethering in Aperture article. I purposely focused on the ‘Pencil Sharpener’ lettering to show any changes to the depth of field, as extension tubes will significantly reduce the lens depth of field.
The first photo below is taken without the extension tubes attached. The focal point is about 50cm from the lens. The sharpener is lighted from the right side with a single desk lamp.
The next photo is with the 9mm extension tube. The focal point is about 9cm from lens. You can see how the magnification has been dramatically increased. The depth of field has been reduced, but it still allows all of the lettering to be in focus, with only the front and back edges of the sharpener being slightly out of focus. I would estimate the depth of field would be about 3 to 4cm.
The next photo is with the 16mm extension tube. The focal point is about 6cm from lens. You can see how the magnification has been increased further. When this close to the subject adequate lighting can start to become an issue. The depth of field has been reduced further, with the end of the lettering now out of focus, and the front of the sharpener more prominently out of focus. I would estimate the depth of field would be about 2cm, which makes manual focusing harder. I found moving the camera forward and backward when the lens was focused at its closest setting to be easier than trying to manually focus the lens.
With I tested the 30mm tube or where the tubes are stacked, the focal distance was reduced to only a couple of cm and the magnification too close to result in an acceptable image for this article. For photographing very small objects, this would be okay, but I found that getting adequate lighting was an issue as the front of the lens was obstructing the side light. Also, the depth of field was reduced to less than a cm. If you use a longer lens (I was only using a 50mm), the depth of field and magnification effects would be less dramatic, and the larger extension tubes would be more applicable.
Overall I have enjoyed using the cheap eBbay extension tubes, and recommend them for anybody looking to start macro photography on the cheap. The lack of electrical connections may put you off if you have lenses that do not include aperture rings, but the work-around is not that onerous.
Tags: Macro Photography
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