OM Macro and Extension tube


Mu-43 Veteran
Nov 4, 2010
I have OM 50mm f3.5 macro lens with fotodiox OM to :43: adapter. I have not bought the 25mm extension tube yet but I am wondering if the my adapter is working as extension tube. It seems like fotodiox and 25mm extension tube is similar in size. What do you think? Should i still buy extension tube and get even more magnification?

Here are the two links Fotodiox Lens Mount Adapter, Olympus OM Zuiko Lens to MFT Micro 4/3 (Four Thirds) System Camera Mount Adapter, for Olympus Pen E-PL1, E-P2, Panasonic Lumix DMC-G1, G2, GH2, GF1, GH1 G10,: Camera & Photo Olympus EX-25mm Macro Extension Tube for E1, E300 & E500 Digital SLR Cameras: Electronics


Super Moderator
Dec 15, 2009
Huntsville, AL, USA
Real Name
The thickness of the adapter takes into account the flange difference between OM and mFT so the lens can focus to infinity. The ex-25mm is a 4/3 macro adapter for 4/3 lenses, not OM lenses.


m43 Pro
Oct 26, 2010
Steeler Country
The correct OM to m43 adapter thickness should be 26mm. The register for the OM is 46mm, m43 register is 20mm.

The OM had these extension tubes:
7mm manual
7mm auto
14mm manual
14mm auto
25mm manual
25mm auto
65-116 adjustable auto tube

If you use any OM auto lens in the reverse position, you should use the manual tubes, this allows the aperture to be set at various stops.

Some other register:
Nikon F 46.5mm
Leica R 47mm
Leica M 27.95mm
Olympus Pen F 28.95mm
Canon R/FL/FD 42mm

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