Canon 25 mm f:3.5, Руководство пользователя

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TELEPHOTO
2 0 0 mm f : 3 . 5
CANON LENS
LENS ELEMENTS: 7
LENS MOUNT & HEAD: NON-COLLAPSIBLE,
REVOLVING
MINIMUM APERTURE: f : 22
DISTANCE SCALES: 10 ~ 300ft, or 3 ~ 100m, inf
ANGLE OF VIEW: 6°
MAGNIFICATION : 4x
COATING: PURPLE
MIRROR BOX, FOCUSING LENS, LENS HOOD,
UV FILTER, DOUBLE CABLE RELEASE, LEATHER
CARRYING CASE
A telephoto lens with magnification of 4x ,
this lens is preferred by photographers who
need a more powerful magnification than the
135mm lens offers. In speed and resolution,
it equals the Canon 135mm lens. Combined
with the mirror box, which is supplied with
the lens, it enables one to use a Canon Camera
as a single-reflex camera. The mirror box is
identical to the one for the 400mm lens.
D E P T H O F P H O T O G R A P H I C F I E L D
When a lens is brought into focus on any one subject, [here is a certain surrounding area which also
will appear in focus. This area can be evaluated from the distance scale calibrations. For instance,
if we were to calculate it using a 50mm lens brought into focus on an object 25ft away, and using an
f:4 aperture, the area of photographic depth would be an area on both sides shown on the scale
1x4. That is in this case, an area approximately between 18ft and 40ft. Everything within this area
would be in accurate focus. In the same manner, with an aperture reading of f : 1 1 , an area 12ft to
infinity will be clearly seen.
The photographic depth is deeper according to the smallness
of the size of the aperture and the longer the distance of the
subjects from the camera. This depth under converse con-
ditions would become shallower.