Macro extension tubes (description)


This is the first of three instalments on the comparison of three sets of macro extension tubes for MFT cameras: Macro extension tubes (description)Macro extension tubes (glare), and Macro extension tubes (lens mount).


Disclaimer: I have no connection to any of the suppliers of the items compared in this test. I bought them from different on-line sellers. Although some of the products I bought have serious design flaws I have tested only one copy of each, bought in July 2017 (Kenko), June 2017 (COMIX), October 2015 (PIXCO). The items in production at the time you read this post may be of an updated design and different quality. It is also necessary to be aware that in the case of some Chinese brands, cheap and expensive versions of an item may exist.


Neither Olympus nor Panasonic sell macro extension tubes for Micro Four Thirds lens mount. There are several third party alternatives. I have bought three of them, I will describe here my experience using or trying to use them. In eBay photographs they all look rather similar, and the three sets I bought consisted of two tubes, with lengths of 10 mm and 16 mm. As I will describe bellow, there are major differences. The sets I own are Kenko “Extension Tube Set DG for Micro 4/3” (100 € to 140 €, Kenko Tokina, Japan), COMIX CM-ME-AFMM (35 € to 55 €, Commlite, China), PIXCO “Extension Tube Set DG  for Micro 4/3” (15 € to 20 €, PIXCO, China).

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The three sets of macro extension tubes.

One thing worth noting is that the set from Kenko is the only one of the three that displays the official Micro Four Thirds logo printed on the tubes and in the packaging and manual. This should ensure that the mount dimensions and placement of electrical contacts are within specifications, and the tubes widely compatible with Micro Four Thirds cameras and objectives. The body and lens/camera mounts are made of metal, and the inner surfaces are flat black, giving rise to very weak reflections. The set is rather hefty weighting 116 g. The mounts have very slight rotational play, but almost none along the lens axis.

The cheapest set, the one from PIXCO has a plastic body and metal lens/camera mounts. It is very light weight at 50 g. The inside shows an attempt to reduce reflections by means of a surface with fine ribs similar to those in the Kenko, the the surface is not as matt, giving rise to some diffuse reflections. The mounts have a bit more rotational play than in the Kenko, but no major problem with axial play. The location of electrical contacts is good enough and the rotational play small enough to make the set of tubes fully functional. However, what I dislike is that the metal used in the lens and camera mounts seems to be rather soft, and its surface rough. Mounting or dismounting a lens produces a grinding sound, which quickly results in visible mark on the lens mounts of the tubes. So, it is of rather poor quality as one could expect from its price, but is fully functional (at least under light use).

What could seem like a bargain, the COMIX tubes, very nicely packaged, including a nice small pouch for storage, turned out to be those of worse in use. Looked at casually they seem identical to the Kenko ones. The body of the tubes is plastic, but mounts are made from metal with a nice and smooth finish. Even the location of screws and the shape of the levers used for unlocking the mounted lens are almost the same as in the Kenko. On inspection they are light, weighting 59 g. On looking at the inside, I was surprised to see that the surface is smooth and shinny, just plain black plastic. On use, another unwelcome surprise: there is considerable rotational play together with a very important axial play. Electrical contacts do work in spite of axial play, but axial play as a result of the weight of the attached lens should cause under normal use a misalignment of the focus plane on the sensor (like in a tilt lens or a tilt adaptor). The dimensions of the mount are clearly not within reasonable tolerances and the metal springs way too weak to keep even light weight objectives in the required position and alignment. In other words, a nice looking set of tubes that is in practice non-functional.

Why is a matt black ribbed interior surface important? By changing the objective to sensor distance we project the image from further away. Consequently part of the light hits the inner walls of the tube. Reflections cause flare and can drastically decrease image contrast. Being macro extension tubes just tubes, one could think that as long as the camera and lens remain connected, the same lens using difference tubes should result in images of the same quality. This is not necessarily true, because both misalignment and  internal reflections can deteriorate image quality.

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The three sets of extension tubes, from left to right, Kenko, PIXCO and COMIX. The secondary light source was behind the tubes and slightly above, to avoid artefacts a large source was used: a 27″ computer monitor. The secondary light source used to test for reflections was at a shallow angle trying to simulate possible reflections in actual use.

All illustrations, text and measurements are of my own authorship, and copyrighted.

(c) 2017 Pedro J. Aphalo


 

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