What do I need to consider before using and adapter with OM-D E-M1

Started Feb 1, 2014 | Discussions thread
hindesite Veteran Member • Posts: 3,592
Re: Be aware of FD adapters...

Paul Auclair wrote:

mjh04 wrote:

At this point, I have a Canon set-up with a number of lenses and an Olympus set-up with its lenses as well. While I certainly appreciate the ability of the Canon 5D Mk III and the L series lenses, my go to kit when I travel has quickly become the E-M1.

I am starting to think about adapters to be able to occasionally use some of my Canon glass (especially longer focal lengths), but am not sure I even know what I need to consider before stepping into this. If anyone can point me in the right direction or me some direction here, I would greatly appreciate it.

Some questions that I have are:

Does adding an adapter between the lens and the body change in any way the 2 to 1 focal length multiplier? e.g. Will my 70-200L IS F/4 lens have an effective focal length of 140-400? Is the f/4 aperture still the fastest aperture, or do I lose a stop or two like you do with a teleconverter? Do I have to manually manage the aperture on the Canon before removing it from the body resulting in having only a single aperture available or are there quality adapters that allow you to manually adjust aperture on the adapter itself. IBIS will work great on other lenses, but is it necessary for me to switch Image Stabilization on the lens off or does it matter?

Thanks for your advice.


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Mike Hedge

I have both types of FD mounts.

you may already know most of this but i'll explain for other's 'enjoyment'...

the are two Canon FD mounts. the earlier FD bayonet and the newer FD breech lock (FDn).

Neither of the mounts' aperture assembly is engaged(operable) unless the lens is in a operational position (properly mounted to a body/adapter/or in the case of the bayonet...a rear lens cap will also work). This means that if you simply pick up an FD lens turning the aperture ring will do nothing inside the lens. The blades are wide open (resting) and not visible.

All of the FD to Micro4/3 adapters I have seen are of the same basic operation in that they have a simple OPEN/LOCK ring that simply slides a pin (back and forth) which engages/disengages the breech lock (FDn) mount's main aperture signal pin. This engages/allows for the blades to operate(open up/stop down) according to aperture ring settings.

The FD bayonet mount (which has the silver ring next to the aperture ring) works fine with any old FD adapter. There is no need/use for the OPEN/LOCK ring/pin on an FD adapter when used with a bayonet mount FD. The aperture mechanism works simply when mounting the lens to body/adapter/lens cap.

FDn (breech lock) is a different story however.

The LOCK/OPEN ring on the adapter simply 'slides' it's own pin to engage and force the len's main aperture signal pin into the operating position. There is no detent or interlock on any of the adapters I am aware of thus far (and I am still searching).

I have experienced and since discovered others too have experienced a major issue.

So, what happens is this...you mount the adapter with the ring in OPEN position then slide the ring over to the LOCK position. Voila now you can adjust aperture. Again there is no detent or interlock so....the adapter's pin is simply pushed back towards the OPEN position due to the spring load force of the lens' aperture signal pin. Voila...no more aperture control (aperture wide open).

As far as I can tell the only resistance that the adapter's OPEN/LOCK ring has comes from grease packing. There should be some sort of interlock/detent but I haven't found an adapter with it.

I've asked several FD-M4/3 makers about this issue and few have responded (well..less than a few). Rainbow has responded (and there adapter looks identical to mine) that they have no reports of this issue with their FD adapter.

I'd suggest out of any adapters spend time (and maybe more money) looking for a 'good' FD adapter if you plan to use FDn. Otherwise the inexpensive (ebay seller) adapters are really quite good enough these days. I have a few different brands. The cheapy lens adapter makers are listening and have improved their products (light baffling, tighter machining tolerances, better finish coatings).

That's all useful information Paul, but the OP mentions owning a 5DIII and glass so I'm assuming his L glass is recent and not FD.

The FD mount might be the most complex one to use and adapt, it certainly raises almost as many questions about it as the Pentax M42 variations (which is ironic, given that you'd think an M42 mount is as simple as it gets. Not so).

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