One of the things I've noticed in recent years as LED's have improved is that the light has got 'harsher', cf car headlights, very often we don't want that kind of light, just a little glow to see where I've left kicked over the vino.
I reckon the problem of low-intensity light from dimmable LED sources is twofold:
- Nasty low-frequency PWM dimming leading to stroboscopic effects that even if you can't perceive as flicker, mean your eyes have to work harder to fixate on a given target, as they overshoot during the dark period. Sort of thing that gives you a headache if you read by it.
- That the colour temperature of an LED source doesn't appreciably change
[1] when dimmed. If it's a high-efficiency (or low-cost) emitter with a fairly high colour temperature, this means you end up with a light that's far too blue for those of us used to incandescent sources, and it just feels wrong.
If it's being driven at full brightness with a 100% duty cycle then these problems go away, but obviously you then have a ludicrously bright light that's inappropriate for just loitering within tent.
Additionally I seem to be becoming somewhat photo-sensitive. We were in the lakes last year and every time someone at the other end of the site switched their small supernova on I had to retreat to the tent with crippling pain behind my eyes.
Sympathies. As barakta's photo-sensitivity has become a problem, I've realised how ubiquitous horrible light sources can be. Bonus points for the ones in the migraine clinic.
[1] If you dim by controlling the current rather than the duty cycle, it goes a bit wibbly in the bottom 10% or so.