I was recently talking to my grandfather who is a WW2 vet and was a navigator on a B-29 Bomber. The missions he flew were exclusively at night and they had the bottom of their plane painted black to help camouflage themselves from spotlights. He mentioned that when they were caught in a spotlight by the Japanese, they would turn off the spotlight before firing at the plane, thus giving the B-29 crew the chance to dodge the fire of the guns. My grandfather concluded, unlikely as it seems, that they didn't have enough power to fire the guns while keeping the spotlight on. Does anyone have any knowledge of why this happened? Or did it not?
From this source, I found that:
Most Japanese AA guns do not use electrically-operated data computers, instead used fixed sights. Source mentions:"Lateral and vertical deflection, slant range and super-elevation are determined by using drums, dials and disks located on the gun.
Coordination between searchlights and AA guns are found to be poor, Quoted from the source: "Our night missions against Japanese objectives have encountered some searchlight activity, but the synchronization between searchlights and AA artillery is usually poor or lacking entirely."
However, I did find this neat tidbit, they seem concerned about AA location discovery:
"The Japanese follow the fundamental rule of never divulging their position by gunfire. They will often withhold their AA fire until they are absolutely positive they have been discovered, and then begin firing with every weapon available, including their rifles. Often they set up a barrage of trench-mortar fire against our minimum altitude attacks. "
Another thing I did also think of is stalking planes:
"Sometimes the Japanese use stalking planes, flying at the same altitude as our bombers, to relay information to the gun crews. When these stalkers are present, adjustment of antiaircraft fire has been more rapid than normally. The Japanese are also clever about pre-estimating the altitude of clouds as a factor in determining the altitude of the attacking planes. "
It's possible that the japanese are concerned about the stalking planes being identified from the searchlights and consequentially, shut them off before firing the AA guns.