The one situation where this seems to come up is that I'm using PWM duty cycle to control a constant current LED driver. Because my light is far too bright at

The one situation where this seems to come up is that I'm using PWM duty cycle to control a constant current LED driver. Because my light is far too bright at full intensity, the driver has a PWM pin that lets attenuate that. however, because I'm taking extremely fast images (sub-millisecond exposures), if I use a low PWM frequency (<1MHz) I see image artifacts. I am trying 1MHz PWM (generated by my arduino) on a solderless breadboard, and I see flaky behavior when I increase the PWM beyond 250KHz or so. Things look fine on my scope, but the LED itself often doesn't behave as expected.