That all makes perfect sense but I suspect that the "master body" and
"master lens" are really electronic test fixtures. I'd just like to
know what is being calibrated on the lens.
Chuck Norcutt
Johnny Johnson wrote:
> At 05:19 PM 6/21/2007, Chuck Norcutt wrote:
>
>> Backfocus = the lens is focused behind the subject.
>> Frontfocus = the lens is focused ahead of the subject.
>>
>> But I've never really understood why this is considered a fault of the
>> lens. The lens is delivering the image and the camera is making
>> contrast measurements and directing the lens to move forward or back and
>> ultimately tells it to stop moving when the camera has decided that the
>> focus is good (or good enough). Perhaps the lens coasts a bit while
>> moving and doesn't stop fast enough when told to. But that would also
>> mean the camera body didn't double check the final focus. Inquiring
>> minds want to know more.
>
> Chuck,
>
> I don't know how the systems function but, at least with Canon, both
> the lens and the body require calibration. Up until I purchased a
> Canon 100/2 I hadn't had any AF problems but that lens, out of the
> box, front focused by ~9" over 25'. I sent it to Canon service in
> New Jersey and it came back working fine.
>
> The party line at Canon is that they won't calibrate a given lens and
> body together. Bodies are calibrated to a master lens and lenses are
> calibrated to a master body. That way you avoid screwing up the AF
> on several lenses that had been previously working (as described
> about a D200 in another message ). I would think that Nikon's
> standard procedure would be similar to Canon's. Makes me wonder if
> someone screwed up at the service center in the case of the D200.
>
> I did read at message once from someone that said a technician at a
> Canon service center told him that he had calibrated the customer's
> body and lens together. Who knows what a given technician may do or
> say to get an irate customer off his back.
>
> Later,
> Johnny
>
> __________________________
> Johnny Johnson
> Cleveland, GA
> mailto:jjohnso4@xxxxxxxxxx
>
>
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