I've read that same stuff and simply don't understand it. What is
inaccurate? Even a guy with a simple lathe in a machine shop can turn
an adapter that's accurate to within 0.001". If the thickness of the
adapter is off by +/- 0.001" how does that translate to terrible
results? Or is it not the thickness of the adapter but whether the two
faces are plano-parallel?
Chuck Norcutt
On 12/4/2010 5:12 PM, Jeff Keller wrote:
> If the lens has floating elements to compensate for close focusing, an error
> in register distance can degrade the performance significantly. 16-9 tested
> a Nikon lens with a cheap adapter and got terrible results. When they got an
> accurate adapter the performance was dramatically better.
>
> Jeff Keller
>
> -----Original Message-----
> From: Chuck Norcutt [mailto:chucknorcutt@xxxxxxxxxxxxxxxx]
> Subject: Re: [OM] Changing lens mount
>
> To clarify, if the register distance of the adapted lens is shorter than
> that of the body being adapted to you can never reach infinity without
> inserting an optical element (which acts like a low power
> tele-converter). But you could use such a setup as a macro lens
> provided you don't mind not being able to focus further than a meter or
> two or three. However, even if the register distance of the lens is
> longer than that of the body it must be enough longer to accommodate the
> thickness of an adapter. One millimeter or thereabouts is probably
> about the practical minimum. The has to be enough metal for strength.
>
> Chuck Norcutt
>
> On 12/3/2010 3:43 PM, Andrew Fildes wrote:
>> No, but it means that you may not achieve infinity focus.
>> And as most lenses move a lot at the close end but not much at the long
> end, you may miss inf. by quite a lot.
>> Andrew Fildes
>> afildes@xxxxxxxxxxxxx
>>
>>
>>
>> On 04/12/2010, at 7:24 AM, AS wrote:
>>
>>> The differences in register are very small....sometimes a mm or less,
> what difference does that make? Does this affect the ability to focus?
>>
--
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