I believe Wayne's logic is sound, although I never saw it pointed out
before. The thickness of the adapter affects the position of the lens
barrel while the cam/follower indicate the relative positions of the
focussing helicoid and camera body... No?
Tom
Sent from my iPhone
On 22 Jan 2009, at 21:55, "Jim Nichols" <jhnichols@xxxxxxxxxxxxx> wrote:
> Wayne,
>
> The thickness of the adapter does affect the point of contact
> between the
> lens cam and the rangefinder cam follower. Therefore, if the
> adapter is
> not the correct thickness, the RF image will not come together at the
> distance at which the lens is actually focused.
>
> Jim Nichols
> Tullahoma, TN USA
> ----- Original Message -----
> From: "Wayne Harridge" <Sent: Thursday, January 22, 2009 3:29 PM
> Subject: Re: [OM] Photos from Bessa
>
>
>>
>>
>>
>>
>>> Stephan@xxxxxxxxxxxxxx <> wrote:
>>>
>>> the linking of the rangefinder... is fragile, since there are many
>>> scopes of problems
>>>
>>> - need for an helicoid on the lens
>>> - accuracy of the threadmount flange
>>>
>>
>> Actually, I don't think the thickness of the M to thread adapter is
>> really
>> critical. From what I understand the rf cam is part of the lens
>> construction and bears directly on the cam follower of the body, so
>> the
>> adapter doesn't contain any rf linkage - correct ? If the adapter
>> is a
>> bit thinner than spec you won't be able to focus quite as close,
>> you'll be
>> able to focus a bit past infinity and the distance scale on the
>> lens will
>> not be accurate *but* the rf focussing should still be accurate. Of
>> course if the adapter is a bit thicker than spec you won't be able to
>> focus to infinity (bummer !) but the rf will still be accurate at
>> shorter
>> distances.
>>
>> ...Wayne
>>
>>
>>
>> Wayne Harridge
>>
>> http://lrh.structuregraphs.com
>> --
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>>
>
>
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