Minolta 7000 - Page 13

4. Principle of auto focusing (explanatory diagram)
(1) Light path
The light from taking lens passes through main mirror (half mirror), reflects on sub mirror, and
strikes on AF sensor.
AF sensor is composed with optical elements (IR cut filter, condenser lens, separating lens ete.)
IR (intreved ray}
cut filter
O Condenser lens
and CCD image sensor.
Separating lens
ccD
(2) AF sensor
® Separating lens is composed with 2 extremely small lenses {lined side by side). The image, formed
by taking lens, is separated into two images (in right and left) and formed on CCD image sensor
by separating lens.
CCD image sensor sequentially outputs electric charge of each picture element, as phase difference
signal of 2 images, to [C¢ through ICs.
Phase differance detection system detects focusing
state comparing positions of 2 images.
0
Comparison
block
Reference
block
izg
Comparison
block
is
composed
with
more
picture
Sa
seelements
than
reference
block
so
that
comparison
GW: WU block can detect focus amount and defocus direction.
Separated images on reference
block and comparison black