Re: filmscanners: RE: filmscanners: nikonscan

[hersch@silcom.com]

Ed, have you tried offsetting the x,y starting position for focusing by a Nikon 
scanner (eg LS-30) to see if an offset on a curved piece of film stock would be 
better? Or does the scanner head off in whichever direction that makes the 
contrast increases by itself?
Hersch

 In a message dated 10/9/2001 2:13:38 AM EST, bill_sub@billfernandez.com 
> writes:
> 
> > >>From what Ed has said in the past, the focus position seems to be in one
> >  >direction only - I *think* along the length of the film.
> 
> On scanners where VueScan does the focus itself, I read one scan
> line in the middle of the scan area and adjust the focus position
> until the contrast is at a maximum.  The entire scan line is used to
> compute the contrast, and I use the sum of the absolute values
> of the difference between adjacent pixel values to compute
> the contrast.
> 
> On the Nikon scanners, I send the scanner the X,Y position
> of the focus (in the center of the frame).  I'm guessing that
> it adjusts the focus position until the contrast is maximized
> in the region around this X,Y position.
> 
> Regards,
> Ed Hamrick
>