RE: filmscanners: LED Illumination for Film Scanners

[rafeb <rafeb@channel1.com>]

[rafe b:]
>> The Leaf also "works around" this issue by
>> doing three scans -- presumably using a different
>> filter with each pass.  But the Leaf can't
>> control illuminant intensity or spectral content
>> the way that the Nikon scanners do.


[Austin:]
>I don't quite know what you mean by that...  How does the Nikon control
>spectral content?  They don't change the color of the LEDs, do they?  The
>color is fixed...

My mistake.  I suppose if Nikon is using just 
R, G and B leds, there's no tweaking of spectral 
content.  That idea comes from the Kodak white 
paper I cited earlier, where LEDs of several 
different hues were employed.


>The Leaf does control the lamp brightness, and the lamp brightness of a
>non-point linear diffuse light source is going to be quite a bit more even
>than an array of LEDs...


I don't know how they do it, but apparently they 
and many others do it with a good deal of success. 
Nikon's been using LEDs in their film scanners for 
several years.  If there were a systematic problem 
with this, I think we'd have heard about it by now.

It could well be that the LEDs are far enough from 
the focal plane so that they appear diffuse.  That's 
purely a guess on my part.


rafe b.