200
Maintenance / Further information
G-30-1529-en
OPMI® VISU 160 on S8, S81 & S88 Suspension Systems
Issue 5.0
Printed on 09. 10. 2006
Magnifications / Fields of view
Using the magnification factor
γ
of the zoom system, you can calculate the
total magnification of the surgical microscope according to the following
formula:
where:
f
tube
is the focal length of the binocular tube
f
obj
is the focal length of the main objective lens
γ
is the magnification factor set on the zoom system
M
eye
is the magnification of the eyepiece
Example:
f
tube
= 170 mm, f
obj
= 200 mm,
γ
= 1.6 and M
eye
= 12.5 x.
The resulting total magnification is:
If the total magnification M
T
of the surgical microscope is known, the field-
of-view diameter FoV
D
can be calculated using the formula:
The field-of-view diameter FoV
D
is the diameter of the circular area of the
surgical field which can be seen through the eyepieces.
FoV
N
in the above formula stands for the field-of-view number of the eye-
piece. This number is marked on our widefield eyepieces.
Using M
T
= 17.0 from the example above, the field-of-view diameter ob-
tained with a 12.5x eyepiece with a field-of-view number FoV
N
of 18 mm
is calculated as follows:
M
T
f
tube
f
obj
-----------
γ
M
eye
⋅ ⋅
=
M
T
170 mm
200 mm
---------------------
1.6 12.5
17.0
=
⋅
⋅
=
FoV
D
FoVN M
eye
⋅
M
T
---------------------------------
=
FoV
D
18 mm 12.5
⋅
17.0
----------------------------------
13.2 mm
=
=
