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Re: [OM] Sony A7 mirrorless FF body announced

Subject: Re: [OM] Sony A7 mirrorless FF body announced
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
Date: Fri, 18 Oct 2013 10:03:41 -0400
I'm quite surprised by all these comments about poor quality from 
adapters that may be off side-to-side by as little as 10 microns.  10 
microns!!  That's 0.00039" and less than the best quality (0.0005") 
promised by this high precision CNC machine shop. 
<http://www.midwestllc.com/>  I suspect that a typical camera body's own 
lens mount may not be finished to that tolerance.  Nor the lens itself 
either.  And, of course, the errors of the two pieces are not independent.

I have nothing but cheap ebay adapters and have never noticed any 
problems with Zuikos on the 5D.  On the other hand, I've never used any 
wide angle Zuiko on the 5D other than my 24/2.8.  It's never 
intentionally used to take a photo of an object at 6 feet (as the 
lenrentals article notes for their measurement test) but it is usually 
focused at about 6 feet.  The reason is that is that it's only ever used 
for landscape work and always at the hyperfocal distance for f/11 which 
is about 6 feet.  When at f/11 and focused at 6 feet the entire range 
from 3 feet to infinity is in focus.  But for the precise focusing range 
between 3 feet and infinity the lens would have to move about 3/4mm. 
I'm quite sure that any error in my lens and lens adapter mounts is 
hidden in the depth of focus.

Chuck Norcutt


On 10/17/2013 4:12 PM, Iwert Bernakiewicz wrote:
> I had adapter issues on the 5D for all my wide angle lenses. Since I have
> the high quality japanese rayqual adapter my results for wide angle
> photography have improved a lot...
>
> Iwert
>
>
> 2013/10/16 Moose <olymoose@xxxxxxxxx>
>
>> On 10/16/2013 4:10 PM, usher99@xxxxxxx wrote:
>>> Looks very exciting for alt lenses indeed.  It has gapless microlenses
>>> but sometimes alt lenses don't play nicely with them
>>> with short registration distance cams.  Some physically large adapters
>>> seem to degrade MTF--an unexpected finding
>>> by Roger at Lensrentals:
>>>
>> http://www.lensrentals.com/blog/2013/09/there-is-no-free-lunch-episode-763-lens-adapters
>>
>> I've never understood why the Oly adapters are so expensive. Now perhaps I
>> do. And I'm doubly glad that I got a genuine
>> Oly OM=>µ4/3 adapter free on a promo.
>>
>> Could it be a factor in 80/4 macro on adapter vs. 60/2.8 native µ4/3 macro
>> lens test? That the 80/4 Auto covers a much
>> larger field might mean no problem if adapter is close to perfect.
>>
>>> I have seen quite good data that smaller adapters like Nik-Canyon have
>>> a modest effect and  no real world consequence.
>>
>> OM=>Canon are also thin and one piece. How perfectly centered is hard to
>> know, although they can't be far off and still
>> fit. :-)
>>
>> Adapted Moose
>>
>> --
>> What if the Hokey Pokey *IS* what it's all about?
>> --
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>>
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