As I was re-reading this it occurred to me to express the tolerances
here in another way. The depth of focus (the image side of depth of
field) is about 3/4mm or 75 times the stated required precision of 10
microns.
Chuck Norcutt
On 10/18/2013 10:03 AM, Chuck Norcutt wrote:
> 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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