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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: "Walters, Martin" <Martin.Walters@xxxxxxxxxxxxxxxxx>
Date: Wed, 15 May 2013 11:48:12 +0000
Chuck:
The m4/3 mount is essentially an adapted Pen F mount. I imagine the format 
change (4:3 to 3:2) is enough of a problem when copying slides.  In the next 
little while, I'll be trying out my Pen F bellows and 38 macro (don't have the 
slide viewer). From a very brief test, everything fits fine and I'll be 
interested to see what quality I get. Any other macro stuff I have (not a lot) 
is OM.

Martin 

-----Original Message-----
From: Chuck Norcutt [mailto:chucknorcutt@xxxxxxxxxxxxxxxx] 
Sent: Wednesday, May 15, 2013 7:32 AM
To: Olympus Camera Discussion
Subject: Re: [OM] Oly 4/3 vs m4/3 lens mounts and adapters

Thanks, Martin.  Wayne's message where he actually tried it verifies your 
thoughts.  You are correct that the crop factor has to be considered when 
copying a 35mm slide onto 4/3 or m4/3.  That's why I was looking for a 
magnification of 0.5X rather than 1X as you normally do for 35mm to 35mm or 
digital full-frame.  I could use the Canon 5D and the 50/3.5 macro at 1X but I 
was trying to figure out how to do it with the E-M5.  Unfortunately, the 
minimum magnification of the 50/3.5 macro on the bellows is larger than 0.5X 
and you can't capture the full frame.

There is still the problem of different aspect ratios.  0.5X comes very close 
to capturing all of the horizontal dimension of a mounted slide. 
Mounted, the visible area of the slide is 35x23mm.  So, 35mm has to fit into 
the 17.3mm horizontal dimension of the 4/3 sensor and 23mm has to fit into the 
13mm vertical dimension of 4/3.  If you fill it vertically (using 0.57X) you 
clip almost 3mm of the horizontal dimension of the slide.

Maybe it's back to the 5D where the real problem is getting enough light to 
focus accurately.  I guess I should try using the adapter with AF confirmation.

Chuck Norcutt


On 5/14/2013 9:05 PM, Martin Walters wrote:
> Chuck:
> 4/3 lenses only fit on m4/3 with an adapter (MMF2 or 3, I think). So, 
> your  OM to 4/3 will not fit either.
>
> I thought that the crop factor on the 4/3 (or m 4/3) sensor gave 
> greater magnification than on 35mm (or full frame). I'll let others correct 
> me here.
>
> Martin
>
> On 14/05/2013 7:40 PM, Chuck Norcutt wrote:
>> 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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