HP 4890 Scanner, Focus problems

[john rehn]

I bought a HP ScanJet 4890 some weeks ago.
Mainly for scanning 35 positives in paper frames.

My problem is that the focus seems to be somewhat
random. Sometimes I get the resolution I expect
But most of the time is definitely below the 2400 dpi
that I use. ( spec is 4800 dpi )
I can scan the same image and get different result
at different scans.
Is there a fixed focus or is the scanner doing any
focusing operation ??
Or should I return the scanner as faulty ??

Any comments ??

 

[false_dmitrii]

I bought a HP ScanJet 4890 some weeks ago.
Mainly for scanning 35 positives in paper frames.

My problem is that the focus seems to be somewhat
random. Sometimes I get the resolution I expect
But most of the time is definitely below the 2400 dpi
that I use. ( spec is 4800 dpi )
I can scan the same image and get different result
at different scans.
Is there a fixed focus or is the scanner doing any
focusing operation ??
Or should I return the scanner as faulty ??

Any comments ??

4890 is usually described as having a fixed, wide DOF lens. There's no
software focus control, at any rate. Search this group for earlier
messages that describe how to find and use a flatbed's focus "sweet
spot" (thread on 9/15 mentions it, and there are others from some
months ago). Try flipping the slides over. Make sure the slides are
as flat as possible and not warped. Some people seem to find it
necessary to dismount their slides for the flattest possible film
surface. Again, there are old threads on this topic.

My own experience was that 2400 & 4800ppi negative scans came out
functionally identical, but I don't have super-sharp photos. *If* I
understood correctly, I think Kennedy McEwen has taken issue here with
the notion that a *softer* image is necessarily lower-resolution. The
idea here is that proper sharpening will restore much of the perceived
detail. Search for some of his posts from the past year.

Either way, it doesn't sound to me like the scanner is faulty.
Nobody's posted any claims that their fresh Epson flatbed scan is as
razor-sharp as one from a dedicated film scanner.

false_dmitrii

 

[false_dmitrii]

4890 is usually described as having a fixed, wide DOF lens. There's no
software focus control, at any rate. Search this group for earlier

Either way, it doesn't sound to me like the scanner is faulty.
Nobody's posted any claims that their fresh Epson flatbed scan is as
razor-sharp as one from a dedicated film scanner.

My sincere apologies. I can't believe I wrote all that. I just now
realized that when I saw "4890" I made the mental jump to the Epson
4870. Maybe some of my comments will point you in the right direction,
but if any of them are accurate regarding the 4890, it's blind luck.
It *is* a general rule that unsharpened consumer flatbed scans can come
out up to twice as soft as their same-resolution film scanner
equivalents.

false_dmitrii