Too Dark?

[tibear]

Firstly, I'm in Canada where the sunset is at around 9:40 PM on a field with no lights. Last night I had a game that was threatening rain the entire game. Needless to say it was dark from the first pitch. Bottom of the last inning around 8:30 when the batter hits a sharp grounder to F4 that bounces at the last second and catches F4 in the upper chest. Fielder goes down holding his chest, I immediately call time to get help for the fielder.

One of the parents screams out that it is too dark to play and I'm responsible for the injury. I ignore the comment and go to see how F4 is doing, the visiting manager then comes over and says that F4 got hit because he couldn't see the ball. (He certainly seemed like he could see the ball because he got down immediately after the hit and was waiting for it to arrive when it bounced up and hit him.)

I tell the coach that I'm not having any problem picking up the ball too which he complains that it was going to start raining any second and I should end the game. That was an easy comeback, "I'll call the game when the rain comes NOT when it looks like it might rain." I then tell the manager that I haven't seen any fielder give any physical indication that they are having trouble picking up the ball. (i.e. standing there looking for the ball after it has been hit)

It was getting dark enough that I wouldn't have started another inning but because it was the bottom of the last inning I just wanted to get this one over with.

My question, what criteria do you use to judge whether it is too dark to continue the game? Given this situation should I have asked for new baseballs to simply appease the visiting manager? Call the game? Or let the game continue as I did?(It was over in 5 minutes)