90
Stand lamps, cold-light illuminators and fibre-
optic lamps, etc. are suitable sources for micro-
scopy.
The image is observed in the microscope tube
and focused by turning the knurled ring (73.10).
The magnification can be changed continuously
in a range of 1 : 4 by adjusting the zoom ring
(73.7).
When changing the magnification with the zoom
control the image has to be slightly refocused
with the knurled ring (73.10). The zoom
magnification factors can be read on the scale
(73.8). The magnification also changes when the
distance between the object and the macro
attachment is varied.
Like the slide overlay device, the macro overlay
(Fig. 73) only works in the 50/50 beamsplitter
position (switch rod in middle position) of the
FSA 25 PE tube.
The microscope illumination is left switched off
to avoid disturbing image brightening.
The object is placed on the stage under the
mirror housing of the macrodual zoom (73.11)
and illuminated.
Fig.␣ 73␣ ␣
Macro device on FSA 25 PE tube with tube adapter
1
Tube flange,
2
Coupling ring,
3
Reflection optics,
4
Coupling
ring,
5
Macro adapter,
6
Screw ring,
7
Zoom setting ring 1 : 4,
8
Scale of zoom factor,
9
Scale of magnification factor of the
working distance,
10
Scale of object distance from the bottom
edge of the mirror housing,
11
Mirror housing
1
3
5
11
10
8
7 9
6
4
2
Operation of the macro device
