Well, found this gem from Wolfgang Luth at u-boat archive's patrol
reports in 1941.
"21.59 Four-shot on tanker: Range = 3000 meters, target angle 80°, speed = 9 knots.
M i s s e d s h o t !
Can only be explained by an underestimation of the range
through the periscope with the full moon. (emphasis mine). The tanker was first found again in the periscope late, because it had zigzagged away from the boat.
Apparently he was again on his old course and so had increased the range to the boat.
After 10 minutes a torpedo detonation was heard. End of run detonation was presumed.
22.27 Surfaced, pursued.
24.00 CE 9598 ESE 2-3, bright moonlit night
02.12.41 60 nm south of the Azores
04.00 CE 9689
The moon set in an hour, a half hour afterwards the dawn begins.
In this period the surface shots must fall."
So I guess that answers the question about scope attacks at night.