RE: re Re: Headlight Hype? or Facts

["Smith, Kirby A" <kirby.a.smith@lmco.com>]

Which applies especially during the day when it is bright, and provides the
perception of less sensitivity.  When driving at night, even with the
instrument panel turned down to a barely readable level, the iris is not
fully open (7 mm) if the headlights are sufficiently bright.  I have never
closely observed iris behavior as one is subjected to oncoming vehicles to
determine what effect it might be having.  But note that the attenuation is
only by the ratio of the pupil diameter squared, not a big deal between 4 mm
and 6 mm relative to the range of background luminance.

kirby

> ----------
> From: 	rcohen@ameritech.net[SMTP:rcohen@ameritech.net]
> Reply To: 	rcohen@ameritech.net
> Sent: 	Friday, March 12, 1999 3:56 PM
> To: 	Robert.Houk@East.Sun.COM; kirby.a.smith@lmco.com
> Cc: 	quattro@coimbra.ans.net
> Subject: 	RE: re  Re: Headlight Hype? or Facts
> 
> The problem is that your eye has a gain control called the iris.
> 
> Rob
> 
> -----Original Message-----
> From: owner-quattro@coimbra.ans.net
> [mailto:owner-quattro@coimbra.ans.net]On Behalf Of Robert Houk -
> WorkGroup Server Firmware
> Sent: Friday, March 12, 1999 3:27 PM
> To: kirby.a.smith@lmco.com
> Cc: quattro@coimbra.ans.net
> Subject: Re: re Re: Headlight Hype? or Facts
> 
> 
>    The diff between a 80/100 and 55/60 bulb is only just discernable.  I
> think
>    ...
> --- and ---
> 
>    Huw is right.  The eye is logarithmic in response.  Further, there are
>    ...
> 
> Isnt' the eye progressively more sensitive at low light levels than at
> high light levels? I.e., at low-light-levels ("night"), doubling the
> light energy is substantially more perceivable than at high-light-levels
> ("day")?
> 
> 					-RDH
> 
>