A small pinpoint light source is always best in my limited experience to uncover minor flaws. Specifically, a pinpoint light source along with the area coverage of the beam illuminating the surface is necessary to find the outlying ripples of swirls. With my eye about a foot away from the surface, I hold the LED flashlight about a couple of feet away and watch its reflection as I "wave" the light in a circular motion to reveal imperfections.
Although I'm by no means a well-experienced detailer, this is my personal method of surface examination and getting up-close and personal with the paint. With sunlight, I have to bend myself at odd angles around the car. With a powerful flashlight, it's an okay substitute indoors or during the evening and I can choose the angle where the light is coming from to make my inspection easier.