HP 4850 out of focus in slide scanning

Hallo!

I have a HP 4850 and I have bad slide/negative scans. I think it is a focus
problem.
I found this post; he explain how to adjust focus, but I do not understand
how!! I am italian, but I ask you: is it wroten in a correct English?
Do you understand?

"Some month ago I bought a HP Scanjet 4890 with the intention to scan my
slides. The resolution was not what I expected.
I measured the resolution using the "slanted edge" method ( see some other
threads in this group ). It looked more like the resolution of a 1200 dpi
scanner. Got no help from HP support. The reaction to my measurements was
basically "that's the way it is"
After some testing I made a guess that it was an "out of focus" problem and
that the focus position was some mm below the glass plate. So I made the
decision: "make it or brake it". Opened up the scanner, removed the cylinder
with the lenses.
Shorted the cylinder with 1 mm in the end that was closest to the detector.
That way I had the possibility to adjust focus
to a "more far" position. Well as it turned out 1 mm was too much but 0.2 mm
was about right. That moved the focus about 3 mm to a position about 1 mm
above the glass plate. Just right for my framed slides. It is slightly out
of focus when scanning images, but I have not any need for max resolution
with images. One other thing I found is that the focus position is moving
with temperature, so make any testing with a warmed up scanner. I guess that
the HP Scanjet 4850 have the same problem."

Thank you a lot
E.

"Equinox" wrote in message
...
Hallo!

I have a HP 4850 and I have bad slide/negative scans. I think it is a
focus problem.
I found this post; he explain how to adjust focus, but I do not understand
how!! I am italian, but I ask you: is it wroten in a correct English?
Do you understand?

"Some month ago I bought a HP Scanjet 4890 with the intention to scan my
slides. The resolution was not what I expected.
I measured the resolution using the "slanted edge" method ( see some other
threads in this group ). It looked more like the resolution of a 1200 dpi
scanner. Got no help from HP support. The reaction to my measurements was
basically "that's the way it is"
After some testing I made a guess that it was an "out of focus" problem
and that the focus position was some mm below the glass plate. So I made
the decision: "make it or brake it". Opened up the scanner, removed the
cylinder with the lenses.
Shorted the cylinder with 1 mm in the end that was closest to the
detector. That way I had the possibility to adjust focus
to a "more far" position. Well as it turned out 1 mm was too much but 0.2
mm was about right. That moved the focus about 3 mm to a position about 1
mm above the glass plate. Just right for my framed slides. It is slightly
out of focus when scanning images, but I have not any need for max
resolution with images. One other thing I found is that the focus position
is moving with temperature, so make any testing with a warmed up scanner.
I guess that the HP Scanjet 4850 have the same problem."

Thank you a lot
E.


He has a few words that are spelled correctly, but the meaning is wrong.

"Shorted" should be "shortened" as in make less long.

"make it or brake it" should be "make it or break it". As in to separate or
cause to separate into parts or pieces. Or to destroy the object.

What he did was cut off some of the cylinder the lens is mounted into, thus
giving him some movement to be able to find the focus point on the glass.

He had to have a lot of trial and error to find the correct spot.

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CSM1
http://www.carlmcmillan.com
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