Hi Guys,
I experienced the focusing problem with USM 50/1.4 lens. It resulted exactly
as Joe described with "defocus spasm". As I found out, when I slightly
touched the AF/MF sliding switch, the lens focused OK. I gave it to
authorized Canon service and they stated that the AF/MF sliding switch was
not contacting properly. It was also the brand new lens, but I got a repair
under warranty. From now on it works fine. I wonder if you checked the AF/MF
switch with your lens? It may look that it is a manufacturing problem of
Canon which occurs with focusing problem.
Regards,
Maciej
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Date: Tue, 4 Sep 2001 12:26:01 -0400
From: "Austin, Joe (NCI/IMS)" <[EMAIL PROTECTED]>
Subject: RE: EOS Re: 300mm f4 IS
Howard,
I had a similar experience with a 300f4IS a few months back. The lens was
bought new through mailorder. As I used it over the next week I noticed
that the lens would have a problem with focusing, it didn't happen all the
time but enough to be very frustrating. The symptom was this: as the lens
would get close to focus it would seem to suffer a minor seizure where the
focus would snap in and out very rapidly bringing the subject in and out of
focus rapidly before finally settling in on the focus , or not.
As this was occurring a faint chucka-chucka-chucka noise could be heard in
concert with the 'defocus spasm'. I could not find anyone who had had a
similar experience so I called Canon and talked to them about it. The tech
was not familiar with the symptoms his suggestion was that if the lens was
new send it back to the seller for a replacement. I decided to do that and
the new lens has operated flawlessly. Curiously the vendor made the
determination that the returned lens was 'not defective' and denied my
return shipping credit request. I called them and explained that the lens
was definitely defective but a cursory examination would probably not
identify the symptoms. They did give me the credit but might have returned
the lens to the shelf anyway (it was not B&H).
You sound like you are in the same situation I was, you're not sure if you
have a defect or not. My advice to you is what the Canon rep told me... if
you are not happy with the lens return it. The 14 day return at B&H does
not apply to defective merchandise. Explain the problem and ask for a
replacement lens.
Good luck,
Joe.
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