Re: filmscanners: Stains and Grains (was Yellow Stain)

[Arthur Entlich]

Lynn Allen wrote:
> 
> Hi Frank,
> 
> OK, then that would mean that the sensor array is vertical to the line of
> travel, and the scan is horizontal, as we thought, and that makes sense. Now
> optics *could* cause light drop-off, but frankly I don't quite understand
> how that mechanism works, either. I'd almost have to see it--and
> conemplating that, what I *see* is a part or two left over after I've
> re-assembled my Scanwit! ;-) (I actually *did* that with an electric
> typewriter, once. For some reason, it still worked! :-))
> 
> Best regards, and keep us plugged in--LRA
> 


OK, I'm gonna try some very simple ASCII art here.
This is how scanners which move the film work.  There are others (Nikon,
for example) which move the light source and CCD assembly and the film
stays put.

This is a cross section.

                _________________________
                     light source           (remains stationary)
            VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV


 ===<<<======<<<=====<<<======<<<=====<<<======FILM FRAME (which moves
                                               left one "segment"
                                               (pixel length) per 
                                               "reading"
                     .............
              ........           ........                 
           ...                            ...
        ...                                 ...
      ...                                     ...
     |                                           |  << LENS (remains
      ...                                     ...      stationary)
        ...                                 ...
          ...                             ...
            .........             .........
                     .............


                 ====== ====== ======    < CCD sensors (remains
                 R.CCD  GR.CCD BL.CCD                 stationary)  


Usually either lens or CCD units move for focusing.


Art