Canon Extension Tubes Review
Video Review
You can watch my video review of these extension tubes on YouTube at the following link:
Using Extension Tubes For Macro Photography
Product Images
Sample Images
The following sample images should tell you all you need to know about extension tubes. They were taken with my Canon EF 85mm f/1.8, which is the lens I tend to use most with extension tubes.
This lens, which I use a lot for product photography, has a minimum focusing distance of 85cm. Some objects that I photograph are big enough to fill the frame at a distance of 85mm, but not small objects. Obviously, I want to fill the frame as much as I can to use as many pixels as possible so that I get the highest resolution possible.
This first image is with the lens about as close as I can get, which is roughly 85cm. Please note the following distances in this example are all approximate.
As you can see, at 85cm the object looks quite small. The first four sample images have been resized for the web, but they haven't been cropped.
Canon EOS M6 | Canon EF-EOS M Mount Adapter | Canon EF 85mm f/1.8 | Gitzo GT2541EX
The next image is with the EF 85mm f/1.8 plus a 12mm extension tube. With this combination I was able to reduce the minimum focusing distance to about 50cm. Of course, the closer you can get to the subject the more magnification you get.
Normally, the thing that prevents you from getting in closer is the minimum focusing distance of the lens, but this is the limitation that extension tubes allow you to overcome.
Canon EOS M6 | Canon EF-EOS M Mount Adapter | Canon EF 85mm f/1.8 | Canon 12mm Extension Tube | Gitzo GT2541EX
In the next image I replaced the 12mm extension tube with a 25mm extension tube. With a 25mm extension tube I was able to achieve focus from a distance of roughly 42cm. Remember, this image is of the entire frame without any cropping.
Canon EOS M6 | Canon EF-EOS M Mount Adapter | Canon EF 85mm f/1.8 | Canon 25mm Extension Tube | Gitzo GT2541EX
In the next image, I used both extension tubes giving a total of 37mm. With 37mm of extension tubes I was able to achieve focus from a distance of approximately 36cm. The little SD card has now filled the frame.
Canon EOS M6 | Canon EF-EOS M Mount Adapter | Canon EF 85mm f/1.8 | Canon 12mm Extension Tube | Canon 25mm Extension Tube | Gitzo GT2541EX
With all this extra magnification, if you want to crop a part of image it will look a lot better because you are using a lot more pixels.
First, here's a crop from the top image above taken without any extension tubes. As you can see, the resolution is poor.
Canon EOS M6 | Canon EF-EOS M Mount Adapter | Canon EF 85mm f/1.8 | Gitzo GT2541EX
The following image is a crop from the image taken with 37mm of extension tubes. You will be able to see that there is much more resolution, even at ISO 3200.
Canon EOS M6 | Canon EF-EOS M Mount Adapter | Canon EF 85mm f/1.8 | Canon 12mm Extension Tube | Canon 25mm Extension Tube | Gitzo GT2541EX
The following image was taken with the Canon EF 40mm f/2.8 pancake lens (another very sharp lens) and Canon 25mm extension tube. The circle on the $1 bill is about 29mm. This image has been resized, but not cropped. It could actually be a lot larger and still retain all of this detail.
The only problem with this combination is that the focusing range is very narrow. Too near, or too far away, and it won't focus. I achieved focus at approximately 155mm. The minimum focusing distance of this lens without any extension tubes is normally 300mm.
Canon EOS M6 | Canon EF-EOS M Mount Adapter | Canon EF 40mm f/2.8 Pancake | Canon 25mm Extension Tube | Gitzo GT2541EX
And here's another part of the same dollar bill. I had the camera on a tripod and used the self-timer to activate the shutter to avoid touching the camera, thus preventing any self-induced camera shake.
For maximum detail I set the ISO to 100, whereas usually I use the Auto ISO feature. Most lenses perform best at around f/8 so I put the camera in AV mode and selected f/8. To obtain the correct exposure the camera selected a shutter speed of 0.4s. This is not ideal if hand-holding the camera, but as it was on a tripod it didn't matter. I didn't use any artificial lighting.
Canon EOS M6 | Canon EF-EOS M Mount Adapter | Canon EF 40mm f/2.8 Pancake | Canon 25mm Extension Tube | Gitzo GT2541EX
There is so much magnification that you can assess and compare the printing quality of bank notes from different countries.
Canon EOS M6 | Canon EF-EOS M Mount Adapter | Canon EF 40mm f/2.8 Pancake | Canon 25mm Extension Tube | Gitzo GT2541EX
Extension Tubes
Extension tubes contain no optical elements. They are simply hollow tubes that allow lenses to be mounted further away from the focal plane of a camera while preserving all the electrical contacts so that the lens functions as if it were attached directly to the camera body.
Thus, they are very different to extenders/teleconverters that do contain optical elements.
What's the point? All lenses have a minimum focusing distance. The addition of an extension tube in between the body and lens reduces the minimum focusing distance. The lens can therefore get nearer to the subject, and the result is a magnifying effect. Using an extension tube is a cheap way of turning a regular lens into a macro lens.
Of course, nothing comes free. The addition of an extension tube also decreases the maximum focusing distance. Most lenses can focus to infinity but with an extension tube they can't, so they lose normal functionality. There is also a loss of light, and vignetting can occur.
Kenko Tubes
Extension tubes have no optical qualities, just electrical contacts. There is no reason why products from different manufacturers shouldn't be exactly the same.
If I had seen a set of Kenko tubes, I would probably have bought them. There are three tubes in the Kenko set (12mm, 20mm, 36mm) and they are cheaper than Canon. All I could find were original Canon items so that is what I bought.
I read one report about lenses attached to Kenko tubes falling off, but I guess that isn't normal.
The original Kenko tubes didn't support EF-S. The only difference with the version II tubes is that they support Canon EF-S Lenses. In addition to the red EF mount dot, there is also a white EF-S dot.
Magnification and Compatibility
How much additional magnification will an extension tube give you?
While Googling this I came across some quite complex formulae. The formula I like (because I can understand it) is:
Additional Magnification = (Extension Tube Length) ÷ (Lens Focal Length)
When using a 25mm extension tube with my Canon EF 100mm f/2.8L IS Macro lens, the extra magnification would be:
25mm ÷ 100mm = 0.25 (or about ¼ more magnification)
What about compatibility?
Extension tubes reduce the minimum (and maximum) focusing distance of a lens. With short lenses that have a fairly short minimum focusing distance in the first place, the addition of an extension tube can actually bring the minimum focusing distance to behind the front element - thus making it impossible to focus.
I read that it is not advisable to use extension tubes with lenses shorter than about 50mm, but the results from my EF 40mm f/2.8 pancake and an extension tube are very good.
Canon Specifications
I've only included the lenses that I use. At the time of doing this, information for the 100mm f/2.8L IS Macro lens wasn't available because it had only been announced fairly recently. Besides, purpose-built macro lenses have short minimum focusing distances and thus there is less benefit using extension tubes with them compared to using extension tubes with non-macro lenses.
Extension tubes can't be used with the Canon EF-S 10-22mm Ultra Wide Angle lens.
- Canon EF85mm f/1.8 USM + EF12mm II Extension Tube
Magnification
0.27x - 0.15x
Focusing Distance Ranges
498mm - 723mm
Working Distance
345mm - 595mm
- Canon EF300mm f/4L IS USM + EF12mm II Extension Tube
Magnification
0.30x - 0.04x
Focusing Distance Ranges
1338mm - 7795mm
Working Distance
1061mm - 7518mm
- Canon EF400mm f/5.6L IS USM + EF12mm II Extension Tube
Magnification
0.16x - 0.03x
Focusing Distance Ranges
2893mm - 13449mm
Working Distance
2580mm - 13136mm
- Canon EF17-40mm f/4L USM + EF12mm II Extension Tube
Magnification
Focusing Distance Ranges
Working Distance
WIDE
0.83x - 0.70x
TELE
0.59x - 0.32x
WIDE
155mm - 159mm
TELE
206mm - 271mm
WIDE
2mm - 5mm
TELE
53mm - 118mm
- Canon EF70-200mm f/4L IS USM + EF12mm II Extension Tube
Magnification
Focusing Distance Ranges
Working Distance
WIDE
0.23x - 0.17x
TELE
0.28x - 0.06x
WIDE
554mm - 627mm
TELE
1008mm - 3467mm
WIDE
318mm - 401mm
TELE
782mm - 3840mm
- Canon EF85mm f/1.8 USM + EF25mm II Extension Tube
Magnification
0.44x - 0.32x
Focusing Distance Ranges
386mm - 428mm
Working Distance
218mm - 285mm
- Canon EF300mm f/4L IS USM + EF25mm II Extension Tube
Magnification
0.37x - 0.09x
Focusing Distance Ranges
1216mm - 3946mm
Working Distance
924mm - 3654mm
- Canon EF400mm f/5.6L IS USM + EF25mm II Extension Tube
Magnification
0.21x - 0.07x
Focusing Distance Ranges
2460mm - 6610mm
Working Distance
2132mm - 6282mm
- Canon EF17-40mm f/4L USM + EF25mm II Extension Tube
Magnification
Focusing Distance Ranges
Working Distance
WIDE
Not available
TELE
1.02x - 0.70x
WIDE
-
TELE
196mm - 218mm
WIDE
-
TELE
28mm - 50mm
- Canon EF70-200mm f/4L IS USM + EF25mm II Extension Tube
Magnification
Focusing Distance Ranges
Working Distance
WIDE
0.42x - 0.38x
TELE
0.37x - 0.14x
WIDE
407mm - 410mm
TELE
879mm - 1790mm
WIDE
166mm - 169mm
TELE
638mm - 1549mm
Conclusion
Dedicated macro lenses have two fundamental qualities - they are very sharp and they have short minimum focusing distances. They also tend to be quite expensive.
Many non-macro lenses are also very sharp, but they have long minimum focusing distances which prevent you from getting in close up. However, this limitation is easily overcome with extension tubes.
In the same way that a teleconverter can effectively turn one lens into two lenses, extension tubes can turn 'normal' lenses into macro lenses.
I use original Canon extension tubes, but they are probably the most expensive brand. Kenko are cheaper and I have seen sets of extension tubes from China advertised at around $10. Due to the fact that they contain no optical elements, provided that the physical mounts are OK and they transmit the electrical signals correctly, a set of cheap tubes (in theory) should perform as well as the Canon ones. You can therefore convert some of your normal lenses to macro lenses very cheaply.
I find extension tubes very useful.
Would I Buy One Now?
Yes, definitely. I have a dedicated macro lens, but I would certainly buy extension tubes again. Whether I would buy Canon ones again or a cheaper brand would depend on my financial situation at the time.
I like the flexibility they give me. I do a lot of product photography with ny Canon EF 85mm f/1.8 and there are often times when I want to get in a little closer, but can't because of the minimum focusing distance of this lens.
In these situations it is very easy just to add an extension tube and I can continue doing what I am doing without changing lenses.
Post-Processing
Most original images were shot in the RAW format and converted with Adobe Camera Raw. Noise was reduced using Imagenomic Noiseware Professional. Small amounts of image enhancement were applied using Adobe Photoshop CS2 (curves, levels, saturation) before sharpening using the Smart Sharpen filter (Amount: 30% - 120%, Radius: 0.2px - 0.3px, Remove: Lens Blur).
JPG images were saved with a 'High' quality setting of '8' on a scale of 0-12.
Details
Weight: EF 12mm - 2.3oz/66g; EF 25mm - 3.4oz/95g
Soft pouch: Included
Date Purchased: March 2010
Supplier: Parisilk, Singapore
Price: EF 12mm - SGD$75; EF 25mm - SGD$154
Other Review Pages You May Be Interested In