Wednesday, 10 June 2009

micro 4/3 adapter review: OM mount (Ciecio7 model)

Right about now there is a lot of interest in the micro 4/3rds format with enthusiastic amateurs and perhaps some professionals looking at using legacy lenses on these cameras. Not only is this a cost effective in terms of accessing some fine optics but the adapters are not being made by Panasonic but by many third party groups.

I think this is great as both the photographic community and specialist makers are getting involved in expanding this system. Now not that the makers produce lower quality stuff (in fact quite the opposite) its just that they don't always have the imagination or the inclination to cater to markets like this.

So, here is the adapter from Ciecio7, he's an ebay seller.

Its a nice tidy unit and looks quite nicely made. These adapters are really quite simple animals, and essentially simply stand the lens off from the camera to the right distance. This is because the micro 4/3rds system requires the lens mount to be 22mm from the sensor while other cameras require a bigger distance (called flange distance).

The first thing I noticed when I put on my OM lens was how bloody stiff it was to turn and lock the lens. I mean really. I needed to turn the lens focus all the way round and get a grip on the rubber focus grip strongly. I thought I was going to rip it off.

Once mounted I checked infinity focus (with my Olympus 21mm f3.5 lens) and found that it was off by a bit on the scale. Infinity was at 3 meters on the scale. Now the shorter the focal length lens the more effect that any accuracy of the above flange distance comes into play. With a 21mm lens I reckoned this was about 0.09mm

So I had now two reasons to pull apart the adaptor:
  1. fix that tightness
  2. fix the infinity focus

Fixing infinity focus

Infinity focus was easy to fix, I put a small sheet of shim material of the right thickness between the chromed plate and the black tube surface it screws to. His design makes this easy to do this.

Fixing the tightness

This proved a little more challenging, and required me to understand what the problem was.

If you look carefully at the mount you can see that the flaps on the back of the lens bayonet mount slide under some wing rails on the inner part of the mount.

This holds the lens from falling off the camera and also allows the lens to be tightened down against the front surface of the mount.

For it to tighten down it needs some spring to pull it against the inner surface of the lenses flaps.

if you look carefully at the mount to the left you can see that he's incorporated that into the mount.

I've removed the metal front mount (undo those 4 screws and pay attention to orientation) and you can see it more clear in this closeup of the metal part.

perhaps you can see that what he has done is to split the inner coupling flange and bend it down to provide a a spring as the lens bayonet flap moves under it from left to right (as you rotate the lens on the mount). From this angle you can see the delicate side cut he's put into the ring to allow it to be bent down.

But this is the problem, because this provides way too much spring power and friction. Its not needed and makes the lens so difficult to attach and remove I'm genuinely afraid of damage.

How is this done on the camera? Well since the OM mount method is quite similar to the Panasonic (only the sizes vary a little) I thought I'd just show you how the Panasonic does it. You can see below that a small curved bit of spring metal is inserted in a carved out part.

this applies a more delicate but sufficient force to properly tighten the system. Something else you'll perhaps noice is the red flecks of paint in there. This is something I've found with his other adaptors that the red paint he uses for marking the orientation points for mounting the adaper on the camera are not sufficiently countersunk and bits are cut off by the process. You can guess that these end up inside the camera. I think that this needs reviewing in his design and manufacture as its not a problem with other makers adaptors.

So, placing this plate onto my lens (but I can't turn it) you can see here just how much spring force is applied. In my opinion it was way too much (even though its barely a mm).

partly this is because of the thickness and the width of the spring and partly its because its bent a bit too strongly.

My solution was to carefully lapp down the underside of the ring to make that spring less strong. Like this:

I did this carefully with "wet and dry" paper and checked it against my lens (cleaning carefully each time) before finally remounting with my shim (from above) in place.


While I think that supplying users with a selection of shim material for allowing owners to easily tune infinity focus. This is a good solution to the problems of manufacturing tolerances, however it may not be for everyone. However without doubt this level of "owner adaptation" to get the mounting plate to interface with the lens is just too much to ask.

I would urge Ciecio7 to reconsider his design and either provide a smaller spring tension (by bending it less strongly) or reduce the thickness of the bent component (making it less stiff).

I'd also suggest that he consider more appropriately recessing the red dot so that it doesn't wipe off on the inside of my camera. This is not confined to just this adaptor either, as looking at my FD adaptor from him you can see the same thing happening there too

FD 50mm On Adaptor

So there you have it.

Right now Ciecio7 is (as far as I know) the only maker producing an OM to micro 4/3rds adaptor which is one part, so this alone makes his adaptor worth looking at. If you don't mind it being 2 pieces, Jinfinance on eBay (known also as RJ Camera) presently makes a system which allows you to cover 2 lenses in one go. There might be advantages to that, but then again more joins means more likely hood for inaccruacy to me.

I have yet to get my hands on. It is more expensive than the one from Ciecio7 and I don't find having a two piece design ideal ... I'd rather have one adaptor for each lens. But then that's me :-)

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