I am a new user of Olympus E-M5 (OM-D) mirror-less micro 4/3 camera with exchangeable lenses. I purchased it just recently as a kit with M.Zuiko Digital ED 12-50mm 1:3.5-6.3 EZ lens, FL-LM2 kit flash and HLD-6 power battery holder. I am hobbyist photographer and I must say that I am very satisfied with this new camera of mine. It fits my needs perfectly.
I am Olympus user since 2006 and thus I have various Zuiko lenses, Olympus E-500 DSLR camera and other equipment. With this new E-M5 I also received Olympus MMF-2 as a free bonus to this purchase. It is four thirds lens adapter to micro four thirds lens adapter. So now I can mount any Zuiko four thirds lens directly on E-M5 via this adapter, which is great!

But I face one problem when using Olympus EC-20 Tele Converter 2,0x on E-M5.

When I mount for example this configuration on E-M5:
[E-M5] > [MMF-2] > [Olympus EC-20 Tele Converter 2,0x] > [Zuiko Digital ED 70-300mm/1:4.0-5.6 EZ-7030]

It doesn�t seem to work.

All I can see in viewfinder is black screen.
Remember E-M5 is mirror-less camera so what is seen in viewfinder is actual image captured by sensor with settings applied to it.
Problem is that aperture seems to be left unrecognized and it shows in menu "-.-".
No matter what exposure setting I choose and which program (M, S, A, P, iAUTO).
It shows ONLY black screen in viewfinder.
(Without any change, not even when the lens is targeted into intense light source.)

All parts of equipment are in great condition and without any problems or malfunction.

For example, when I mount this configuration on my old four thirds DSLR Olympus E-500 camera:
(Without MMF-2 adapter, which is of course redundant in this case.)
[E-500] > [Olympus EC-20 Tele Converter 2,0x] > [Zuiko Digital ED 70-300mm/1:4.0-5.6 EZ-7030]
It works just fine and everything runs as expected. Is makes 140-600mm (equivalent of 280-1200mm on a 35mm full frame camera).

Or when I remove teleconverter from the previous configuration of E-M5, such as:
[E-M5] > [MMF-2] > [Zuiko Digital ED 70-300mm/1:4.0-5.6 EZ-7030]
[E-M5] > [MMF-2] > [Zuiko Digital 40-150mm/3.5-4.5]
[E-M5] > [MMF-2] > [Zuiko Digital 14-45mm/3.5-5.6]

It also works without problems and everything runs as expected.

So it seems that problem is when MMF-2 and Olympus EC-20 Tele Converter 2,0x are used together. I realize, as also EC-20 manual book tells, that it is not possible to use for example two Olympus EC-20 together. But MMF-2 is not tele converter, it is just adapter.

Had anyone of you experienced similar problem?
Do you have any suggestions or solutions?
Or is it absolutely impossible to use MMF-2 with Olympus EC-20 Tele Converter 2,0x?

I am not sure if anyone will answer. I realize that E-M5 (OM-D) is quite new camera and thus probably not many people use it.
But maybe someone experienced similar problem on Olympus PEN systems, which I guess are quite similar to E-M5 in their nature.

It is not really that crucial problem for me, because I can still use Olympus EC-20 Tele Converter 2,0x and Zuiko Digital ED 70-300mm/1:4.0-5.6 EZ-7030 on my old E-500 camera.

But I would be much happier if I could use it also on my E-M5...

Thanks for any suggestions or ideas.  

Thank you. Yes, I realized than, that probably I will not get much responses here to such specific question. But I wanted to give it a try anyway. Who knows maybe someone from here could have experienced similar problem.

But I will try to post my question on Olympus specific forums to see whether someone will help.

I think the problem you're running into is that the lens you're using is pretty slow and isn't one that is really intended to use with teleconverter in the first place, even if its technically possible on the original 4/3 format.

I am not sure if this could be the case of speed of lens. If it was only slow, than there should be at least SOME light changes on resulting image if the lens is pointed into very intensive light source, such as into light bulb, with long exposure set. Shouldn�t it?   But the black image in viewfinder, also image on preview display or image itself is not changed. Never! No matter what I do with it, or how long exposure I set. The result is always black, as if NO light reaches sensor. When I demount the configuration from E-M5, I mean configuration like this, without camera:
[MMF-2] > [Olympus EC-20 Tele Converter 2,0x] > [Zuiko Digital ED 70-300mm/1:4.0-5.6 EZ-7030]

And look through it, aperture is wide open and I can see light through it without any problems.

But when mounted on E-M5 it seems to close absolutely somehow, or whatever happens to it, because NO light seems to pass through it.
If the configuration was left untouched when mounted on camera, I mean aperture untouched and left wide open this configuration could be usable even without any electronics. The lens itself has button that can switch it to manual focus.
But once when mounted on E-M5 camera, the light seems NOT to reach sensor COMPLETELY...
And that is odd behavior which I don�t expected...

So I finally found the problem and luckily solved it. There was a minor hardware failure of MMF-2 micro 4/3 to 4/3 adapter which I got as a free gift from the shop to this purchase. I did very careful visual examination of this MMF-2 adapter and saw problem. One of 9 male pins (those compressible pins on upper side of adapter used for connection with lens, or teleconverter, etc.) was stuck little bit lower in height than other ones. It was the most left one. It could be easily overlooked, because it was maybe just about 1 millimeter, maybe even less, lower in height than other ones. But it was stuck there. I tried to move it by some gentle force and it finally moved little bit upper. It is still not on the same height level as other pins, but definitely higher that before. Now it also moves and compresses just like the other ones and it returns to its previous position after compression. So even through it is still little bit lower, it seems to be enough to make a contact. Because, now when I connect teleconverter, with Zuiko Digital ED 70-300mm (or any other configuration of lenses I have) it works! Auto focus, preview image in viewfinder, live preview on screen, etc. Fully working! I am happy now!

So I just wanted to mention it here to conclude it.
As an answer to anyone who will maybe find this thread, perhaps looking for the answer whether E-M5 (OM-D) works together with MMF-2 and Olympus EC-20 Tele Converter 2,0x, such as in configuration:
[E-M5] > [MMF-2] > [Olympus EC-20 Tele Converter 2,0x] > [Zuiko Digital ED 70-300mm/1:4.0-5.6 EZ-7030]

Yes, I assure you it fully works on E-M5 (OM-D)! Definitely when good MMF-2 hardware is used.