Texas Instruments MC-780PIx - Manual (Page 32)

Precautionary Items
4-6 Using the Shutter Modes
4.5 Precautionary Items
Observe the following precautions when operating the electronic shutter.
- The CCD for this camera uses the frame transfer method. At shutter
speeds of 1/500, 1/1000, and 1/1500 second, the exposure period and the
transfer period conflict with the readout period. There is black output from
the line count, which conforms to the shutter speed; the image output fol-
lows. Thus the lower part of the image output cannot be output onto the
screen to the degree of the line count of the black output. Figure 4–5
shows what occurs. Table 4–1 lists the line counts for each shutter speed.
Figure 4–5. Exposure and Transfer Period Conflict With Readout Period
Screen
The line count conforming to
the shutter speed outputs black
The lower part of the image
cannot output to the extent of
the line count conforming to the
shutter speed.
Table 4–1. Line Table Corresponding to Shutter Speeds
Shutter Speed MC-7890PIA MC-780PIH
1/500 22 19
1/750 13 11
1/1000 6 3
1/1500 2 –
- Due to the circumstances noted above, during random shutter, when there
is no shutter trigger input, the camera will be in continuous shutter mode.
Consequently the bottom part of the image is not shown for shutter speeds
of 1/500 through 1/1500 second. Images shot with random shutter have
a full image output without the bottom part eliminated. Thus the image ap-
pears to flicker because the positions shown on the monitor differ.
- When a timed exposure is made of over 1/60 second operating in VI mode,
impurities on the CCD may become exaggerated. Also, due to the occur-
rence of dark current, the image may be rough. The image quality of timed
exposures is uncertain.
- Use non-interlace scanning when in random shutter and VI modes.