... and testing it when you receive it. My first adapter was from a
recommended ebay seller. It worked a half dozen times. He probably got a bad
batch, sold them, heard back from 5% of the buyers, then quit buying from
that source (he actually wasn't selling any for quite awhile afterwards).
I believe someone on the list bought a fotodiox clone which had two pieces
screwed together. The screws pulled out nearly dropping the lens.
The only guarantee is if you get it cheap enough you can try again and still
save money.
... and testing it.
-----Original Message-----
From: Chuck Norcutt [mailto:chucknorcutt@xxxxxxxxxxxxxxxx]
Sent: Sunday, December 05, 2010 9:23 AM
To: Olympus Camera Discussion
Subject: Re: [OM] Changing lens mount
I hear you but I think those problems are solved by looking for highly
rated sellers on ebay as well as asking here about other's sales experience.
Chuck Norcutt
On 12/5/2010 12:16 PM, Jeff Keller wrote:
> Badly built may not mean poorly machined. It may just be a case of taking
> their "standard design" and putting different locking tabs etc on it. The
> thickness could be way off as in the pictures I linked. Both were sold as
> Nikon to EOS adapters, and sort of worked, but the generic Chinese adapter
> was way off on its thickness.
>
> A soft corner could be caused by the adapter bayonet being the wrong
depth.
> When the lens is mounted on the camera the lens could tilt down until the
> bayonet tabs finally caught the mounting flange. Many DSLRs have a prism
> housing that hangs out over the lens. It may not be obvious the lens isn't
> being held in the correct position.
>
> Keep in mind that there are millions of tiny anonymous manufacturers in
> China. Antifreeze in foodstuffs, toxic medicines: a lack of knowledge, a
> desire for a quick profit, no due diligence, anonymously produced can
cause
> dramatic failures.
>
> Jeff Keller
>
> -----Original Message-----
> From: Chuck Norcutt [mailto:chucknorcutt@xxxxxxxxxxxxxxxx]
> Sent: Sunday, December 05, 2010 6:08 AM
> To: Olympus Camera Discussion
> Subject: Re: [OM] Changing lens mount
>
> I'm still having difficulty accepting this except in the case of
> extraordinarily badly built adapters. To put a corner out of focus the
> two faces of the adapter would have to be out of parallel by a
> ridiculously large amount by even the loosest standards of machining.
>
> To illustrate the point consider the notion of "depth of focus" as
> opposed to "depth of field". Depth of field equates to near and far
> focus points in front of the lens. The term depth of focus used to be
> used synonymous with depth of field but as it is now used equates to the
> position of the image plane of those near and far points on the image
> side of the lens.
>
> Now consider your wide angle lens. As an example I'll give you a 24/2.8
> focused at 15 meters (my guess at the distance to the porch as used in
> the test shots at 16:9). Using typical 35mm parameters for depth of
> field at f/8 the near focus point is at 1.9 meters and the far focus
> point is at infinity. On the image side of the lens the depth of focus
> is 0.54mm or 0.022". To cause notable differences in focus in one
> corner of the lens the two faces of the adapter would have to be out of
> parallel by so much as to probably be visible to the eye let alone a
> micrometer. Even wide open and focused only at one meter the depth of
> focus is still 0.003".
>
> I have three cheap ebay OM to EOS adapters. They work just fine except
> that two of them won't mount a couple of my non-Zuiko OM mount lenses
> although all Zuikos mount just fine. I've seen no problems with
> infinity focus and, although I haven't put a micrometer to them there is
> certainly no visually obvious difference in parallelism of the two
> mounting faces.
>
> Are you sure the FM forum correspondents aren't shills for CameraQuest?
> :-)
>
> Chuck Norcutt
>
>
>
>
> On 12/4/2010 11:51 PM, usher99@xxxxxxx wrote:
>> Perhaps stating the obvious but WA's are particularly
>> susceptible to adapter issues. Have seen several examples on FM alt
>> lens forum whereby
>> one side of an image was not sharp due to an uneven adapter. Never have
>> seen a complaint about a Cameraquest one, though may be overkill for
>> many applications.
>> Mike
>>
>>
>>
>> Looks like significantly more than 0.002" in the case of the 16-9.net
>> test:
>> http://www.16-9.net/lens_tests/15mm_2/sigma1224vnikon15f.html
>>
>> picture of adapters:
>> http://www.16-9.net/lens_tests/nikon_adaptors.jpg
>>
>> Jeff Keller
>>
>>
>>
>>
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