Nikon Extension Tube E2 is a 14mm long semi-automatic non-meter-coupled extension tube. The E2 is part of the original Nikon F system. It is one step ahead from the fully manual K extension tube set and the predecessor of the automatic/non-meter-coupled M tubes and the automatic/meter-coupled PK tubes. All the extension tubes mentioned above predate AI-coupling and thus could create damages when used on most of the AI-coupled and CPU-coupled bodies.
For those who have never heard of and/or used extension tube, it is basically a lensless hollow tube that is put between the lens and the camera body to increase the lens’ close-focus capability with the drawback of losing infinity focus. The longer the extension tube, the closer the resultant system can focus. The advantage of such system is that unlike attaching close-up filters in front of the lens, extension tubes don’t introduce loss in optical quality since they are lensless.
The main feature of the E2 extension tube is its semi-automatic diaphragm operation. The lens’ aperture will stay fully openned for bright and easy focusing as long as the plunger tab (see photo above) is pushed in either by your finger or by using the AR-2 cable release. Before firing the shutter, the user will need to close the aperture to the preset value by release his/her finger or disengaging the cable release. For me, this step can be easily forgot and the result will be a totally over-exposed (in some cases, pure white!) image. A note on the AR-2 cable release, it is is NOT the “standard” mechanical cable release (with a metal pin at the end) you would see in a camera shop but a special one from Nikon that is design to be used with some early bodies (e.g. F, F2, FM).
The E2 tube does not provide any meter coupling and thus exposure readings need to be obtained from an external meter with a positive (due to loss of light) compensation factor depending on the length of extension. This compensation factor can either be calculated by formulas or obtained from exposure tables. For people who shoot digital, you may want to use the non-extension TTL meter reading as a reference point and skip the complicated step of finding the compensation factor through trial and error by doing test shots and reading histograms.
Most of the close-up shots on this website is taken by an E2 tube extended Series-E 50mm f1.8 mounted on a D300 body. It is an economical and high image quality setup because the E2 tube (if you can find one) is very inexpensive compared to its AI-coupled successors and the Series-E 50mm f1.8 is a very sharp lens by itself. NOTE: However, like using other non-AI lenses/accessories on an AI-coupled or CPU-coupled bodies, you need to make sure the E2 extension tube will not cause any damage (e.g. damages on AI coupler or CPU contacts) to the camera body before putting it on.
Photo above is taken with an E2 tube extended Series-E 50mm f1.8 and below is a 100% crop of the 12 megapixel original. I am surprised that this inexpensive setup (I paid $25CAD for the E2 and $50CAD for Series-E 50mm with an EM body!) can give such high quality results!
A “Few” More Words on Extension Tubes…
Extension tubes used to be a popular and economical way to produce high quality macro images. However, with the introduction of “electronic contacts only” lenses (e.g. Nikon G lenses) and bodies (e.g. AF Nikon bodies with no AI-coupling), extension tubes that provides both automatic diaphragm and meter-coupling have become more and more expensive to produce. Today, a set of 3 fully automatic extension tubes can cost up to $300CAD. Combining with a basic 50mm f1.8 (about $150CAD) that is going to be used in the system, the final cost is getting a bit too close to an entry-level 3rd party macro lens or even one that is from the original manufacturer. In the past, extension tubes were much cheaper and there was often no need to buy a 50mm lens because the camera should already come with one. However, modern film and digital SLRs (except the semi-pro and professional ones) are almost always being sold with a low-cost mid-range zoom lens. These consumer-level zoom lenses (e.g. 28-80mm, 18-55mm kit lenses) are generally not advised to be used with extension tubes. This is not mainly due to the optical quality but because of their slow maximum apertures especially at the long ends. An extension tube, while not affecting the optical quality of the system, it does introduce loss of light because of the “extension” itself. The combined system of a slow zoom (e.g. f4.5 or even f5.6 at the long end) and an extension tube will mostly render the camera’s AF system non-functional. Even manual focusing will be a very tough job for an experienced photographer.
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