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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: Thu, 16 May 2013 13:04:18 -0400
I'm removing the grain of salt.  I mounted the E-M5 on the focusing 
stage, installed the OM adapter and some OM extension tubes and then put 
the OM body mount from the bellows onto the end of the tubes.  Running 
the body mount into the bellows connector resulted in the E-M5 setting 
in a non-level position on the focusing stage.  I think my guess of 3mm 
(maybe 2mm) vertical misalignment may be about right but it's not the 
height of the body or lens center lines.

I had assumed that the OM body was lower and would align properly. 
Nope, the two camera's lens centers appear to be at the same height so 
an OM-1 on the focusing stage doesn't align either.  The problem of 
vertical misalignment is caused by the height of the focusing stage.

Chuck Norcutt


On 5/15/2013 11:15 AM, Chuck Norcutt wrote:
> 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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>>> Themed Olympus Photo Exhibition: http://www.tope.nl/
>>
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