ASTRODEVICE TC 900, Руководство пользователя

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4. Take the picture again, sharpen the image in the center and check the result.
If the shape in the corner has improved, continue adjusting until the result is
satisfactory. If the shape has worsened, go back half a turn (90 degrees) and
see if a smaller step improved the result. If not, try going back another 45
degrees or go back to the previous setting and start adjusting another screw.
The algorithm is to enter successive turns and observe the results each time.
Assume that 180 degrees (half a turn) is a large shift, 90 degrees (a quarter
turn)
- medium, 45 degrees (1/8 turn) - small, about 20 degrees and less are fi ne
adjustments.
If you know exactly how much the corners of the sensor are shifted (this point was
described earlier), it will be easier for you to get an idea of how much more or less
you should
rotate the screws - one turn is 0.7 mm diff erence in distance where
the screw is, and roughly 0.2 mm in the corner of the sensor. Note that two of the
screws are close to the corners of the sensor, while the third raises the opposite
edge (see
fi g. 30). The action of the screws is therefore not identical. Moreover, a
given corner of the sensor may not be pushed further away from the telescope at
all, but closer than the zero position. Then moving it further away only worsens
the result, so it is necessary to leave it in place and move the others away.
The procedure for making adjustments largely involves adjusting the screws
by trial and error. To ensure that this is not a completely blind job, previous
experiments and specialized software that measures the results will help (these
issues were described earlier). Then the work will be much more methodical.
After each adjustment you should sharpen the image in the center of the frame
and check the result. You need to fi gure out which screw at what turn makes what
correction and thus arrive at the ideal position.