FD to M43 focal reducer problem, also which FD lens do you suggest ?

Started Apr 19, 2014 | Questions thread
OP adygadam Junior Member • Posts: 29
Re: Adapter "open - lock" control issue

fotowbert wrote:

adygadam wrote:

Hello All,

I own a Panasonic GH3 and 4 days ago took the plunge finally after a long debate on speedboosters/focal reducers and ordered a focal reducer FD to M43 from here:

Camdiox Focal Reducer FD to M43

I also ordered an adapter: Canon FD to M43 adapter

A got myself a Canon FD 50mm F1:1.4 S.S.C. lens which is amazing ! No dust specs or fungus and in excellent condition.

The adapter worked like a charm, I was able to change the aperture from F16 down to F1.4 and I believe the FF equivalent focal length would be 100mm (50mm x 2), bokeh was amazing a this makes this lens an excellent short distance portrait lens.

The problem was with the focal reducer, I was only able to stop down to F4.8, after that the aperture was the same to F16. On the contrary the adapter allowed me to stop down to F16.

How do you determine the FR (Focal Reducer) is only stopping down lens to F4.8?

If F4.8 is the position of the lens aperture ring when the blades stop moving as you continue to turn the ring further then the following should prove helpful.


This is the symptom that results from the "open - lock" ring not being moved fully in the "lock" direction. This limited travel is most likely caused by the interference mentioned by others between the lever at the 6 o'clock position on the back of the lens and the FR's optical unit although the travel limit may be within the FR itself.

You could confirm this by comparing the angular motion of the "open - lock" ring of the plain adapter to that of the FR adapter (lens mounted to adapters of course). The rotation should be similar.

Unfortunately the FR adapter's optical unit prevents you from looking directly into the camera end of that adapter and watching how far the 'open - lock" ring moves the lever. This should be possible on the plain adapter but you may need a small dental mirror and flashlight depending upon how the camera end is baffled.

It is a pain to comprehend what is going on from the visual of the back of the focal reducer, therefore I had gave up trying.

I have noticed that when I mount the lens to the adapter the chrome ring will turn around 2 inches until it tightens, whereas with the focal reducer it will turn around 4/8 of an inch before it tightens.

The angular rotation the chrome breech lock ring turns when mounting the lens is usually a function of the thickness of the lugs on the other unit. Thicker lugs mean less rotation of the ring to draw the lens down tight. As the lugs wear you can still have a tight mount by turning the ring until it stops.

Looks like I need to get a fine file and treat the focal reducer's mounting contacts, all I have to lose is £90 ($151) worth of gear xD

I wish if it was the normal adaptor that causing the trouble, an easy quick decision would be made to file the thing.

Many consider this an advantage of the Canon FD breech lock mount over the newer pseudo-bayonet FDn style mount.

  • John
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