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Re: [OM] Oly 4/3 vs m4/3 lens mounts and adapters

Subject: Re: [OM] Oly 4/3 vs m4/3 lens mounts and adapters
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
Date: Wed, 15 May 2013 11:15:24 -0400
A quick and very rough measurement looks like the vertical centerline of 
the E-M5 is about 3mm higher than an OM body.  But take that with a 
grain of salt.  Also, like the E-P1 the tripod thread is off center from 
the lens center by about 9mm.  That, however, could likely be solved by 
drilling and tapping a new hole in the focusing stage.  I'll take a 
better measurement later since this has some promise.

Chuck Norcutt


On 5/15/2013 8:17 AM, Wayne Harridge wrote:
> G'day Chuck,
>
> Something like this should work:
>
> http://www.structuregraphs.com/RandomStuff/15-May-2013/index.html#20130515-A
> .jpg
>
> OM focussing rail with slide copier attached E-P1 with om -> m4/3 adapter
> and 50/3.5 @1:2
>
> The only problem with this is that the E-P1 tripod thread is not below the
> optical axis of the lens.  Vertical alignment is ok.  What is the situation
> with the E-M5 ?
>
> To get good contrast you'd probably need to cover the gap between the lens
> and slide copier with a dark cloth.
>
> ...Wayne
>
>
>
>>
>> Thanks, Wayne.  That answers my question; the 4/3 mount is not physically
>> compatible with the m4/3 mount.  But I'm afraid OM tubes won't solve my
>> problem.  My problem is that the OM->m4/3 adapter is already too long for
>> what I'm trying to do with the bellows and slide copier.  I can't connect
> with
>> the slide copier using tubes alone and adding tubes to the bellows would
>> make the problem worse.
>>
>> Steve Barbour sent me links to the 4/3->m4/3 adapter (thanks, Steve) but
>> that won't help me either.  I would still have to connect that up to an OM
>> adapter which gets me right back to the length problem I'm trying to
>> overcome.
>>
>> What I need is an OM->m4/3 adapter with a 15-20mm section sawed out of
>> the middle.  The 80/4 is probably the right solution but I don't have one
> of
>> those. :-)  I'll have to think about this some more.  What I need is
> something
>> like an m4/3 lens flange glued directly to the back of an OM body flange.
>> Basically an m4/3->OM adapter without the tube between the two mounts.
>>
>> Chuck Norcutt
>>
>>
>> On 5/14/2013 11:28 PM, Wayne Harridge wrote:
>>> I tried to mount one of my OM->4/3 adapters on my E-P1 - too big.  I'm
>>> not surprised actually as I reckon Oly would have copped it from a
>>> whole lot of customers who mounted a 4/3 lens on an m4/3 body and
>> found it didn't focus.
>>>
>>> Perhaps pick up some cheap OM tubes, they seem to be plentiful on that
>>> auction site.
>>>
>>> ...Wayne
>>>
>>>
>>>>
>>>> Can someone who has both systems verify whether or not a 4/3 lens
>>>> fits on
>>> a
>>>> m4/3 camera?  I know it won't focus properly and maybe not even
>>>> operate electrically.  My only real concern is whether a 4/3 lens (or
>>>> OM to 4/3
>>>> adapter) physically fits into an m4/3 body.
>>>>
>>>> The reason I ask is that I was trying to use my OM bellows and slide
>>> copier
>>>> today to see if I could copy slides onto my E-M5.  To do that I need
>>>> a magnification of approx 0.5X.  If I had a Zuiko 80/4 short mount
>>>> macro
>>> lens for
>>>> the bellows I'd be OK.  But my only two macro lenses are my 90/2.5
>>>> Viv S1 and my 50/3.5 Zuiko.
>>>>
>>>> I don't think I can get the 90/2.5 to work at all since at 0.5X I
>>>> think
>>> the image
>>>> of a slide is somewhere beyond the length of the bellows rail.
>>>>     The 50/3.5 macro is only designed to do about 0.68X on the bellows.
>>>> The bellows itself prevents it from getting to 0.5X.  The limitation
>>>> is
>>> imposed
>>>> by the minimum separation of the lens board and camera mounting
>> board.
>>>> According to my possibly dodgy calculations the image plane needs to
>>>> be brought forward about 14mm.  If you were using an OM or 4/3 body
>>>> that wouldn't be possible.  However, I note that the 4/3 to OM
>>>> adapter is about 20mm shorter than the m4/3 adapter.  If I had a 4/3
>>>> adapter on the m4/3 body I think that would give me the extra range I
>>>> need to bring the image plane in and get the 50/3.5 to do 0.5X or
> slightly
>> smaller.
>>>>
>>>> So, can someone answer the physical compatibility question between
>>>> the two mounts, ie, will a 4/3 lens fit onto a m4/3 mount even though
>>>> it might not actually work electrically and certainly can't focus
>>>> even if it
>>> physically fits?
>>>>
>>>> Assuming it does, anyone got a spare OM to 4/3 mount you'd like to
>>>> move on?  Maybe an old one with no AF confirmation chip?  I won't be
>>>> needing anything like that.
>>>>
>>>> Chuck Norcutt
>>>> --
>>>>
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>>>
>> --
>> __________________________________________________________
>> _______
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>
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