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Chapter 4 Focusing 25
Remount the lens to the adapter and set the lens focus adjustment to the
target distance.
4.
Power up the system and, using the application software, select
FreeRun
, and
Safe
mode (Asynchronous).
5.
Choose a fast exposure (0.1 s) and begin data collection by selecting
Focus
(WinView/32).
6.
Note the image on the computer monitor. If it is washed out because the CCD is
saturated, reduce the exposure time. If it is too dark, increase the exposure time.
7.
Double check to be sure the lens focus is set to the target distance and readjust if
necessary.
8.
Taking care not to disturb the lens focus, adjust the lens mount focus for
maximum sharpness in the observed image.
9.
Being very careful not to disturb the lens mount focus, remove the lens from the
mount and tighten the setscrews to secure the lens mount focus setting.
10.
Remount the lens.
This completes the procedure for adjusting the lens mount focus setting. It should not be
necessary to disturb the adjustment again. In actual measurements with real subjects, the
focusing will be done entirely with the lens focus adjustment. Microscope adapters
follow a similar procedure except, in this case, the front part of the lens mount should
not need adjustment. See Chapter 5 for additional information.
Lens Focusing Procedure
Except for the lens mount focus procedure that applies to F-mount lenses as described in
the described above, there is no difference between focusing considerations for an
F-mount lens and a C-mount lens. Simply use the focusing ring on the lens to produce
the sharpest image at full aperture. Then stop the lens down to its sharpest aperture
(probably at a mid-range aperture setting) and adjust the Exposure Time for the best
possible image as observed at the monitor. In microscopy applications, it will also be
necessary to review the discussions in Chapter 5.