[Elecraft] Blue Displays and Visual Acuity

[Ron D'Eau Claire]

Interesting experiment, Alan. I've not tried it but a little research backs
you up! One source (University of Illinois Dept. of Physics) says " The
blue-sensitive cones are the least numerous, and are also spread out away
from the fovea. This is one reason why it is harder to get a sharp visual
impression of something blue than something of other colors." 

I find the sort of white light I use for fine work (5800K color temp) tiring
over time and I've read that the blue end of the spectrum offers better
resolution due to the shorter wavelength. In any event 5800K lights are
"bluish" but contain elements of the whole color spectrum just like
sunlight.  

For something other than "white light", you may be right that a mixture of
blue and yellow light (green) actually works better. 

There's also possibility a psychological effect about "blueish" light (e.g.
sunlight) that has nothing to do with the physiology of vision. We humans
are conditioned to be alert when bathed in "sunlight". Specialists in sleep
disorders often recommend shifting to redder and dimmer lights as we move
toward bedtime. They claim it greatly increases our ability to drift off to
sleep. 

I do know from personal experience that it's hard to see detail in red
light, having sat in many aircraft cockpits with the red night vision lights
on straining to read a legend on a chart! Same is true for the bridge of a
ship rigged for night. 

Whatever the underlying causes, I do find blue light jarring, while redder
light is softer and more relaxing. 

I operate to relax. I was waiting for a hard-core contester or DX-chaser to
say he/she wants to be wide awake and "on edge", that's why he likes the
blue light. That would make good sense, but no one did - so far ;-) 

Never hesitate to challenge me. A forum like this isn't about "being right".
It's about open discussion and learning.

Tnx!  

Ron AC7AC



-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of gard at btinternet.com
Sent: Wednesday, June 17, 2009 11:55 AM
To: Elecraft Mailman
Subject: [Elecraft] Blue Displays and Visual Acuity


Hi
 
I'm really hesitant about challenging such an accepted authority as AC7AC on
any topic.  But I think he is incorrect when he says "blue light provides
the greatest visual acuity."
 
A simple experiment (which I have seen performed) can confirm this.  Project
a graded black and white resolution pattern in white light.  Cover the
projection lens successively with red, green and blue colour-separation
filters and see how many of the patterns the eye can resolve in each case. 
You will be amazed at how few can be counted through the blue filter when
compared with the green or, to a lesser extent, the red.
 
This characteristic of normal human vision is acknowledged in the design of
RGB television systems where less bandwidth is allocated to the blue
signal.  If it's acuity you are looking for, green is your colour, not blue!
 
73 de Alan G4LWA