> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Julian Loke
> Sent: Sunday, March 11, 2001 10:18 PM
> To: [EMAIL PROTECTED]
> Subject: Re: EOS Magnification with 500D Close-Up Adapter.
>
> According to Canon, the 100-400 has a maximum magnification of
> 0.06 (for 100mm) and 0.20 (for 400mm) See:
> http://www.usa.canon.com/camcambin/cameras/eflenses/ef100n400spec.html
>
> I could not get the calculator to come up with a magnification of
> 0.20 for 400mm, unless closest working distance was 2.4m This is
> clearly not the case since the lens can focus down to less than 2m.
>
> The only way to calculate a magnification of 0.20 at the closest
> working distance is if the focal length is between 233 and 300mm !!!
>
> Did I make a mistake somewhere?
No, I get the same numbers as you. I wonder if there could be some confusion
here between "working distance" and distance from focal plane to subject.
Could Canon's people, when computing the magnification for publication, have
used minimum working distance(2 meters plus 400mm)instead of minimum
focusing distance (2 meters)?
Chuck Skinner
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