Hi Tom,
We use a Bencher VP 400 copy stand:
http://www.bencher.com/photo/vp400_50050.php
It has a 60 inch vertical travel, and can handle up to a 40 pound
camera and lens combination centered over a heavy 25x25 steel base.
Itıs a monster and can comfortably handle giclee imaging. It costs
about the same as a large bed scanner (not including electricity,
camera, or a place to put the beast), but throughput is far higher.
For example, last week we needed to image labels for 1200 shellac
and transcription discs (so 2400 labels). Not quite the same as
your need with LP covers, but perhaps similar enough.
For lighting, we used a 10 amp variac powering four 300W halogen
lamps, for 1200 watts of illumination. The variac manages the power
surge when turning up the lights, and it helps extend the life of
the lamps. To keep the heat down for the operator, we bring the
current down to about 8 amps and adjust the color temperature at
the camera to about 3000K.
This level of illumination dominates any ambient light in the
room. It also allows us to stop down the lens to f5.6 or f8
for optimal sharpness and less sensitivity to focus.
The lights are angled to highlight matrix numbers in the runout.
The imaging of the matrix numbers is generally excellent, but
when the matrix numbers are very shallow, a bed scanner is
superior.
To reduce label reflections and image hot spots, we have two
12x24 inch polarizers mounted below the lamps. We find that an
additional polarizer at the lens is not needed, and that a
polarizer at the lights produces more uniformly lit images
than a polarizer at the lens.
Lighting is uniform over a 16x16 area (Iıve not measured
the variation in terms of stops), and still very uniform over
the full 25x25 base.
For maximum sharpness, we use a timed shutter release so that
there is no camera shake.
Altogether, we can get high resolution images of the disc labels
and matrix numbers with minimal distortion and good color correction.
Throughput is about 30 seconds per label, which includes:
* time to pull the disc from a container
* un-sleeve the disc
* align the disc (rotate so text is horizontal)
* photograph with timed shutter release
* re-sleeve the disc
* put the disc back in the container
For uninterrupted production flow, we put the camera on an external
power source instead of battery so we can keep the camera on all
day without worrying about battery charging.
We also tried a large bed scanner, but we couldnıt get sufficient
throughput for this project. Aligning the discs on the scanner
was far more tedious because you cannot see the label - the label
is face down on the scanner, and labels on both sides of the disc
are almost never aligned the same. Of course, you can rotate the
label in post using various image manipulation software, but thatıs
an extra step and yet more time.
If you want truly uniform lighting with no linear distortion and
consistently excellent surface detail (like matrix numbers), a
large bed scanner is the way to go. But the copy stand gets pretty
close and is more than good enough in probably 98% of applications.
The exceptions, as noted above, are with items larger than 16x16
and some items with 3D information like matrix numbers that are
very shallow. And even at 25x25, the image quality and uniformity
are still very, very good.
Regarding 3D, some bed scanners have surprising amounts of depth
of field - 1/4-inch or more - and can scan relatively flat objects
with 3D detail.
_________________________
Eric Jacobs
Principal
The Audio Archive, Inc.
1325 Howard Ave, #906
Burlingame, CA 94010
tel: 408-221-2128
[log in to unmask]
Disc and Tape Audio Transfer Services and Preservation Consulting
On 11/4/14, 5:34 PM, "Tom Fine" <[log in to unmask]> wrote:
>The HP Sprout:
>http://sprout.hp.com/
>
>Of course they don't give the full scanning-area dimensions, only "20
>inches wide", but I noted that
>the surface cover sheet sold seperately is 22" by 16", indicating to me
>that it also covers the
>border areas, and thus the scanning area is likely 20" by 14". If that is
>the case, this may be a
>very quick and convenient way to scan LP covers, magazine pages, book
>text, etc. Flatbed scanners
>are great, but time consuming. I say this as one who has scanned hundreds
>of LP covers the
>old-fashioned way.
>
>One thing I wondered about right off is, how much does ambient light
>effect the scan quality? Must
>you have exactly-placed light sources as you would using a camera stand
>(the big turnoff about that
>method).? Or, does this thing have some sort of system where it ignores
>ambient light and only uses
>whatever light frequency is put out by its LEDs?
>
>I'm also not clear how it's a "3D scanner," as the way its demonstrated
>in the video indiates
>nothing like full 3D scanner functionality (360 degree scanning, fractal
>modelling, etc).
>
>-- Tom Fine
>
