Re: [APML]: Second HP v. Kodak Test

[jbakeman@ix.netcom.com (Jack Bakeman)]

On Fri, 23 Jan 1998 14:41:55 -0500, Ben wrote:

>
>Dave's comments sent me doing further tests. I also contacted HP tech 
>support and they, too, had me do tons of things, including running 
>"regular" negatives and slides to see if it still occurs. Yes, in every 
>case where there is a bright white area on a dark area, the left edge of 
>the white field has one or two rows of reddish pixels and the right edge 
>has one or two rows of blue pixels. Of course, this shows up more (and 
>matters more) on astrophotos, but it does occur in every kind of photo. It 
>also shows up very clearly on moon pictures: the left edge of the moon is 
>reddish, the right edge is bluish (with magnification).
>
>The effect shows clearly on my M20/M8 image. I've now placed a horizontal 
>"slice" of this image on my site, so you can scan across the whole 
>negative. You'll see that the pattern is the same all across....except for 
>one puzzling (vertical) area in which the Red-White-Blue pattern reverses 
>direction (it's on the left 1/3 of my "slice")! Go to the bottom of the   
>page at www.alliancerevolution.com/astro/scanner.htm
>
>
>I am not an expert by any means. But it does appear to me like some sort of 
>misalignment of either the sources or the recorders of the lightbeams. The 
>HP tech told me there are no lenses as in a flatbed scanner, just 
>"mirrors". Does anyone know how these machines work and what might be 
>causing these rainbow edges? Is it my unit, or the design?
>
>Also, it would be very useful to know if other HP scanner owners see the 
>same effect on their units (if they look for it). I know there are many 
>users out there. Please check and let us know.
>
>Thanks for your help,
>
>Ben
>

Ben,

I too have a new HP PhotoSmart Scanner. I looked at some M42 images I
just took and saw nothing like what your slice looks like on my
images. I scanned my 35mm PPF negs in with the HP and looked at both
my image and your slice with Picture Window at 5X mag. to make sure I
was doing an accurate comparison. Sounds like it's not a design
"feature" of the HP, sorry.

-Jack