OPERATION
Photomicrography with
Carl Zeiss
Exposure functions
35 mm SLR cameras
3-10
B 40-046 e 03/99
Example 4:
The longest shutter speed measured with cameras with T2 adapter (Fig. 3-3) for ISO 100/21° and the
open aperture 1.4 is T
max
= 2s, and the shortest shutter speed T
min
= 1/4000 s.
The shortest shutter speed T
min
of 1/4000 s is measured with film speeds ranging from ISO 25 / 15° to ISO
3200 /36°; the longest shutter speed of 16s is only measured at ISO 12 / 12°; the longest shutter speed
with ISO 3200 / 36° is only 1/15s.
According to section 3.2.8.1, no blurring occurs with shutter speeds
≥
1/15s.
Therefore, the working ranges for cameras with T2 adapter (Fig. 3-3) are as follows:
−
shutter speeds 1/15 s...16 s for ISO 12/12°,
−
shutter speeds 1/15 s...2 s for ISO 100/21°,
−
shutter speed 1/15 s for ISO 3200/36°.
☞
Any kind of stray light entering the viewfinder of the camera falsifies the measuring result of
the exposure time to be controlled. Therefore, you should work in a darkened room and, after
reading or aligning the exposure time in the viewfinder, you should always cover the viewfinder
with the eyepiece cover for SLR before the automatic exposure is triggered.
☞
For the setting of the various measuring techniques and exposure modes, and for the display of
exposure times, please see the operating manual of the used 35 mm SLR camera.
3.2.7
Trigger the Exposure
Triggering the exposure by pressing the release button of the SLR camera with your index finger exerts
lateral pressure on the camera structure. This can result in blurred micrographs.
Therefore, the exposure should always be triggered with the cable release attached to the SLR camera.
There should be no strain between the cable release and the SLR camera.
If available, the selftimer function of the SLR camera can also be used to trigger the exposure. The
vibration of the camera structure caused by the short pressing of the release button is no longer effective
until the exposure is triggered after the exposure delay (usually 8 ... 10 s).
