The first extension tubes that Olympus produced for the OM cameras were manual, with no provision for operating the automatic diaphragm in the attached lens. The original manual extension tubes were replaced in 1980 by these automatic versions, which include the necessary couplings for the automatic diaphragm in the attached lens. The Olympus OM tubes are approximately 7, 14 and 25 mm, while the Zuiko 50 mm f/1.8 standard lens has 7.5 mm of extension built-in, and in various combinations they provide extension from zero to 54.5 mm with no gaps. The 7 mm tube is unusually short for an automatic extension tube, and had to be made slightly longer then the manual version. The fact that it was made so short, and that it matches the extension built in to the 50 mm Zuiko standard lenses, demonstrates Olympus’s dedication to their macrophotography range.
The Zuiko Auto-Macro 90 mm f/2 lens that focuses unaided to ×0.5 covers the range ×0.5 to ×1.0 when used with all three extension tube, totalling 46 mm.
In common with all other extension tubes, the additional extension requires exposure compensation, but this is normally handled by the camera’s TTL exposure meter.
The 7 mm extension tube provides enough extension to allow the release lever on the camera mount of the Auto Bellows to clear the overhanging prism on the Canon EOS 5D MkII and Olympus E-500 and E-510 digital SLRs.
The 14 mm extension tube provides just enough extension to allow the release lever on the camera mount of the Auto Bellows to clear the overhanging prism on the Canon EOS 40D digital SLR.
|Length||7.60 mm||14.35 mm||25.40 mm|
|Diameter||61 mm||61 mm||61 mm|
|US catalog no.||104-013||104-014||104-015|
Only one version of each length is known.
No other company seems to have made a tube as short as 7 mm. Sets of 12, 20 and 36 mm tubes were available under several brand names; these provide greater magnification than the Olympus set, but with gaps in the range.
Reproduced with permission from the copyright owner, Olympus Optical Co., Ltd
AUTO EXTENSION TUBES 7, 14, 25
Each of these Auto Extension Tubes incorporates an automatic diaphragm lever to stop down the lens diaphragm to the preset aperture at the moment of exposure as interlinked between the OM camera body and lens for close-up photography. The respective lengths of these tubes are 7mm, 14mm and 25mm, which make seven different lengths by single or combined uses.
|Mount the tubes on the camera.||Mount the lens on the front tube.|
• Use the tube(s) in the following steps:
• Helpful hints for use and maintenance
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