Sekonic SR-1800 Operating Manual page 25

SR-1800
(3) Correcting curled or deformed sheets
Fix curled sheets or formed sheets if they are found.
If the device is forced to read curled or deformed sheets, it will tend to cause a reading error,
sheet jam, no feed, double feed, or skewed feed.
Straight, good sheets Straight, good sheets
Upward curled sheets Upward curled sheets
(4) Correcting folded sheets
Flatten 2- or 4-folded sheets before using them since it may cause a reading error. Make a
sheet check when using them.

Downward curled sheets Downward curled sheets