Friday, December 7, 2012

Kenko Extension Tubes Test (APS-C 1.6x Crop Sensor)

Several month back I got myself a set of Kenko Extension Tubes so I can turn my regular lenses into macro lenses. For those of you who don't know what extension tubes are, they are hollow tubes that goes behind a lens to add space between the lens and the camera sensor. This in turn makes the lens focus closer, in other words, give a bigger magnification. I got the Kenko Extension Tubes because it was recommended to me by many photographers. I know this brand is more expensive than other brands, but it is still cheaper than the Canon branded ones. Also this brand also has the electrical contacts on it so all lens controls is maintained, plus the contacts are all covered so the silver wires don't start distorting the light by reflection. It has been great so far.

FULL RESOLUTION TEST IMAGES HERE

I tested this on 2 of my lenses, the Canon EF-S 18-55mm f/3.5-5.6 IS USM Lens and the Canon EF 70-300mm f/4-5.6 IS USM Lens. You should note in the photos you will see the edge is blurrier than the center. This is because there are barrel distortions on both of the lens (usually not noticeable) but the distortions get really blown up when used as a macro lens. You should also take note the photos were taken on a Canon EOS 7D which uses an APS-C 1.6x crop sensor. In most of the photos, it shows almost the closes focusing distance. Since I don't have a macro rail, I can't get it to the closest possible focus that accurately, but they are still pretty accurate. I have used all 3 extension tubes in all of these photos.

Let's first start off with the test done by the Canon EF-S 18-55mm f/3.5-5.6 IS USM Lens.

Almost closet magnification of a US Quarter (25¢). This was done at the 55 mm end for maximum magnification. The lens was about 1-2 inches away from the subject which really cuts out light. At 55 mm, it is not very practical for in field use, but better off for a non-moving subject in a studio.
Photo Info: f/13, 13 seconds, ISO 100, No Flash (Ambient light from a window)

Test shot of a ruler at 55 mm. Each space is in millimeters. Compared to my camera sensor, the magnification was about 2:1. Field of view is about 18 mm. 
Photo Info: f/13, 30 seconds, ISO 100, No Flash (Ambient light from a window)



Now for the test shots with the Canon EF 70-300mm f/4-5.6 IS USM Lens. This lens gives you lesser magnification, but cuts out less light so it is better off for field work. Please look at the "Photo Info" under each photo as they all look similar, but the exposure time greatly differs! Also remember I only used ambient light for these photos, generally you will need a flash for these kind of photos especially in the field!

Almost closet magnification of a US Quarter (25¢). This was done at the 70 mm end for maximum magnification. The lens was about 5-6 inches away from the subject which cuts out light somewhat. At 70 mm, it is kind of practical for in field use, but better off using a longer focal length and loosing some magnification as 5-6 inches might scare off life subjects (like bugs). With extension tubes, the more you zoom the lens, the farther you can focus, but the less magnification you get (kind of the reverse without using extension tubes).
Photo Info: f/13, 4 seconds, ISO 100, No Flash (Ambient light from a window)

Test shot of a ruler at 70 mm. Each space is in millimeters. Compared to my camera sensor, the magnification was about 1:1. Field of view is about 24.5 mm. 
Photo Info: f/13, 20 seconds, ISO 100, No Flash (Ambient light from a window)

Test shot of a ruler at 180 mm. Each space is in millimeters. Field of view is about 5.85 cm. 
Photo Info: f/13, 2.5 seconds, ISO 100, No Flash (Ambient light from a window)

Test shot of a ruler at 250 mm. The bad focusing was error on my end, not the camera. Each space is in millimeters. Field of view is about 6 cm. 
Photo Info: f/13, 2 seconds, ISO 100, No Flash (Ambient light from a window)

As you can see the Kenko Extension Tubes is a great piece of equipment as you can start off macro photography for cheap! If you are interested in macro photography and are on a tight budget, this is definitely the way to go. I will start sharing with you guys photos of in the field work and studio work using this piece of equipment soon, so please check back! Please don't forget to share my blog posts with your friends! If you would like to get notifications next time I post, you can "Like" me on Facebook or follow me on Twitter and Google+. These links can also be found on the top of the right sidebar.
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