Lowering blue light lowers "sharpness"?
I notice that lowering the color temperature (with f.lux but also monitor temp presets) basically makes small fonts more difficult to read, slightly blurry. This is true in photography where blue tones tend to enhance perception of sharpness.
I wonder if there is any way to counteract the perceived loss of definition when lowering temperature? My intuition tells me they are inherently connected. If anything, boosting color temperature in the morning might increase productivity, it would be nice if f.lux had higher temperature options (over 5000) for "lighting at day" or even "lighting in AM".
Blue light isn't all bad, it is related to alertness and perception.
F.lux has 6500K as its maximum color temperature. Use the sliders. The "Lighting at night" menu is just for choosing color temperatures that are warmer than 2700K when f.lux is in the Night mode.
The only way to counteract the perceived blurriness is by increasing your monitor's brightness. It's not a great solution, but our feeble human eyes react this way and we can't do anything about it. Of course, increasing monitor brightness means your warm color temperature setting will be more alerting and stimulating.
@MadMaxwell red light has a longer wavelength than the other colors, so when it passes through the eye's lens, there's a slight effect of chromatic aberration and it can have the effect of focusing a tiny bit beyond your retina. If you've ever had your eyes checked and done the test where you pick out which side of a red or green letter chart looks sharper (the duochrome test) you've seen this. A more mild f.lux setting will help you.
It's also possible that if you're in a super dark room, your pupils are very dilated and that could have a similar blurring effect though it should be pretty mild.