>> Pierre Bellavance wrote:
>> Does this mean that closest focus at 400mm is 1.569 meters with the
>> 12mm extension and 1.393 meters with the 25mm extension?
>> Is there similar info somewhere about the 500D lens?
> Tapani Tarvainen <[EMAIL PROTECTED]> wrote:
> It brings infinity to 500mm from the front of the lens, ...
> So with it the usable range is 67-82cm from film plane,
> or a working distance range of about 35 to 50cm.
Hi Pierre and Tapani,
According to the Canon table:
http://www.usa.canon.com/camcambin/cameras/eflenses/ef100n400spec.html
with 12mm extension, the greatest magnification is at the long end
(400mm focussed to 1.569 metres.) However, with 25mm extension, the
greatest magnification is at the wide end (100mm focussed down to 0.544
metres), but you lose almost one stop of light.
Tapani's numbers are in agreement with the lens calculator (the 500D
corresponds to a +2diopter closeup lens):
http://members.home.net/jul.loke/
For lenses older than about 1995, you can consult the closeup FAQ:
http://bobatkins.photo.net/info/faq30/closeup.htm
Cheers
Julian Loke
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