scanner "discovery?"

[Ken Weitzel]

Hi...

Accidentally stumbled upon something that may be of
interest to those of you scanning film and slides for
archival purposes. Then again, I may simply be
"re-inventing the wheel". You decide for yourselves

Here's what's happened. Eyes are getting older, getting
harder to see dust on the flatbed glass. See it in the
morning, when the sun glares on it, but then the sun is
also glaring on the monitor. Evenings can see the monitor
perfectly, but can't see the dust well.

So - the light bulb went off; I decided to scan an
empty slide slot. Pull up the gain, and I should see
how much and where the dust was so I could clean at least
the one slot in the template perfectly.

Was jaw dropping astonished to find that the top (nearest
the hinge on Epson) 35mm slot was incredibly noisy (noise,
not dust) at the top, tapering off towards the bottom.

Tried the second slot (in epson's template) and it was
much much quieter. Night and day difference, apples and
oranges. Third one was acceptable, but not quite as clean
as the second. And the fourth was the same as the first,
amazingly noisy, but tapering to worst at the bottom.

Clearly this means that the "sweet spot" at least on mine
is the second slot. Why I have no idea, but promise it's
so.

Having said all that, scanning the identical transparency
in both slots one and two, with the gain at normal, I can
see no apparent difference. But - neat image sure can!!!

I invite comment, and suggest that others experiment
themselves with their own machines before beginning any
big projects.

If I'm preaching to the choir, I apologize.

Take care.

Ken

 

[eastside]

Ken:
Very observant of you. Are you sure you don't recall having read about this
technique previously? Because "sweet spot" is exactly the same term commonly
used in scanning that describes relatively noise-free areas of the scanning
platten. The usual technique is to scan a clean piece of white paper and
then enhance the contrast of the scan. Everyone who owns a consumer level
scanner should do this to find the best areas to place scanning material.
Even film scanners (at least every one that I've owned) display the same
fault. Some professional flatbed scanners employ stitch scanning along the
x-y axes to achieve uniform resolution and quality independent of the
placement of the source material on the platten.
Dane

 

[Peter A.]

This is very interesting, thanks for posting it. Amazing what you learn
in here.

BTW the term 'sweet spot' has been in use in the engineering world, at
any rate, for a very long time indeed

 

[Don]

Here's what's happened. Eyes are getting older, getting
harder to see dust on the flatbed glass. See it in the
morning, when the sun glares on it, but then the sun is
also glaring on the monitor. Evenings can see the monitor
perfectly, but can't see the dust well.

So - the light bulb went off; I decided to scan an
empty slide slot. Pull up the gain, and I should see
how much and where the dust was so I could clean at least
the one slot in the template perfectly.

That's a well known method of spotting dust and scratches on the
flatbed scanner's glass.

1. Clean the glass thoroughly on both sides. <=!!!
2. Lift the lid and scan "nothing" in a darkened room.
3. Afterwards, brighten up the image in an editor until pale gray.
and then...
4. Shriek it horror! ;o)

Another tip for a quick check I discovered accidentally is to lift the
lid in a darkened room and then start a scan with nothing on the
glass, as above. Next, squat down until your eyes are virtually on the
same height as the glass. As the light sweeps down the length of the
scanner it's very easy to spot all debris and glass damage.

Don.