We don’t really have to guess. Some of our more talented reviewers made equipment for measuring intensity vs beam angle. For example, in maukka’s FW3A review, there are detailed measurements of how the beam is shaped with three common optics:
The 10507 is more or less equivalent to a SMO reflector… and the 10511 is essentially the same thing but frosted (similar to OP) so it blends the beam together a bit. I greatly prefer the smoother 10511 beam.
- Smooth reflector = ringy beam, sharp edges, visible artifacts
- OP reflector or frosted optics = smooth beam, gradual slopes, subtle or no artifacts
The effect of an OP reflector or frosted optic is very similar to running a Gaussian blur filter over the beam, and that’s a good thing… unless you want sharp edges.
In any case, that’s not what causes the “fried egg” effect. The XP-L HI beam is still more intense at the center, even when it looks like a fried egg… it just has a visible tint shift there due to the way it emits different frequencies at different angles. It’s not nearly as bad about this “Cree rainbow” effect as most LEDs, but it still happens somewhat. The warmest frequencies go out the sides of the LED, where they bounce off the reflector and end up in the center of the hotspot.
The effect is usually most visible with a large smooth reflector, but it can also be seen even in the non-frosted Carclo optics. Here are those same results, but showing CCT by angle instead of intensity. This is the egg yolk effect:
Regardless, I almost always prefer a smooth change of intensity from the hotspot to the outer edge of the spill. It doesn’t have to be a linear change, but I like to avoid the appearance of any sharp edges. The plateau-shaped beam in the “quick-n dirty Paint” pic above doesn’t really appeal to me.
I liked the FW1A’s beam with XP-L HI… it was very nice. But it was too throwy for my purposes, so I modified it. The effect was very similar to what is shown in the intensity-vs-angle graph above, going from 10507 to 10508. It went from ~22 cd/lm down to about ~10 cd/lm, which made the hotspot wider and less intense. And I’m pretty happy with the result. I wanted ~10 or ~12 cd/lm, and that’s what I got.