Re: focusing in monochromatic light

[T3D john bercovitz <bercov@xxxxxxxxxxx>]

> Those yellow glasses that target shooters wear have been very popular for
> many years, and I have to assume there is something to them...but I haven't
> seen any enhancement of an image when using them.

They're used on grey days when the eye's pupil tends to open up.  
However, they're sold as improving contrast.  Remember that the 
object (target) is very sharp-edged and is in black and white 
so converting to black and yellow doesn't change the amount of 
information and in fact does sharpen up the edges observably.  
The fly in the ointment is that it's hard to maintain focus.  
It should be noted that these glasses are sold to lots of people 
other than target shooters for improving contrast under field 
conditions.  I don't know how it works in the field.  Don't see 
where the gains would offset the losses except in the same cases 
where you would use the fog lamps on your car.

John B


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