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Scanner Optics and Light Path
Film scanners have either fixed focus or variable focus optics in them. We're
not sure which category the SprintScan 4000 falls into, but believe it to be
a fixed focus design, since the software never offered an option to adjust the
scanner's focus, and the scanner itself never seemed to go through a focusing
cycle. Given the extreme resolution of most film scanners, we're surprised that
their lenses can be designed with enough depth of field to insure sharp focus
in the face of minor variations in the film plane position. We're surprised,
but the fixed-focus approach nonetheless seems to work quite well, as evidenced
by the performance of the SprintScan. Of course, the upside of a fixed-focus
design is that focusing is no longer a concern, either in the form of twiddling
a thumbwheel or by waiting while the scanner adjusts its focus for every scan.
In our testing, the SprintScan produced sharp images every time, the sole exclusion
being our unusual "USAF 1951" resolution target, which is a glass
slide with the pattern deposited on one side of it. As with some other scanners
we've tested, with the pattern facing one way, we got sharp results, but decidedly
softer ones with it facing the other. Neither orientation was as sharp as it
could have been though, and there was a lot of "flare", apparently
caused by the great thickness of glass in the optical path. We saw no evident
focus deficiencies while scanning normal slides or negatives.
The SprintScan 4000 uses a special fluorescent light source to illuminate the
film. In the past, we've seen scanners with fluorescent illumination produce
somewhat "softer" scans than those using more collimated light sources.
With the SprintScan 4000 though, we saw no hint of softness in its scans, and
in fact, it produced some of the most razor-sharp detail on our "House"
image that we've seen yet.
Film Handling
Like
most film scanners we've tested, the SprintScan 4000 uses sturdy plastic slide
and filmstrip holders to carry the film through the scanner. Operation is simple,
you first place the media to be scanned into the holder, then insert the holder
into the scanner. The holders have slightly tapered front edges, to facilitate
insertion into the scanner. You insert the holders slightly beyond where you
feel slight resistance, at which point the scanner recognizes the presence of
the holder, pulls it further in, and then moves it back and forth until it's
properly registered and ready to scan the first frame. You can remove the holders
at any time simply by tugging on them: There's a slight resistance, but it doesn't
appear to harm the frame-advance stepper motor at all to override its resistance
while the scanner is idle. The scanner body has openings on both ends, allowing
the end of the film holder to project out the back as successive frames are
scanned. (In the process, requiring a bit deeper work area.)
The
film holder is a fairly standard clamshell arrangement, only this one is hinged
at the front and opens lengthwise. ("Alligator mouth" instead of "clamshell"?)
A series of raised bars on either side of the film opening position the film
side to side, and a clever little sliding gadget with pins that fit the film's
sprocket holes handles fine positioning along the length of the film. The film
adapter worked well, but we did find that we had a bit of trouble with film
that was badly curled lengthwise. It was hard to hold down the film while closing
the clamshell, and the little ridges meant to guide the film laterally weren't
always where they needed to be to catch the ends of the film and keep it aligned.
(Our favorite design for film holders is to have a continuous recess running
the full length of the adapter. This helps greatly with curled film.) The provision
of a control to slide the film back and forth once it was loaded was a very
nice touch though.
The
slide holder has four recesses into which slides can be loaded. A spring-loaded
finger presses one edge of each slide against sturdy ribs that cross the adapter
side to side. There's about a millimeter of play between the edges of a standard
slide mount and the sides of the adapter recess, allowing that much side to
side adjustment of the individual slides. The spring-and-rigid-backstop arrangement
provides for a very positive alignment of the slide to the adapter, but this
turns out to be a bit of a two-edged sword. We've often encountered slide mounts
in which the film was rotated slightly with respect to the cardboard or plastic
mount. Some scanner adapters allow slight manual rotation of the slides to compensate
for poor mounting jobs, correcting for the rotation of the film with a counter-rotation
of the slide in the adapter. The SprintScan 4000's adapter permits no such adjustment,
but the benefit is that there's virtually no chance of inadvertently rotating
a slide in the holder. Another nice aspect of the 4000's slide holder is that
it's very forgiving of unusually thick mounts, such as our glass USAF resolution
slide, or bulky glass-and-plastic mounts.
Performance
Polaroid calls this scanner the "SprintScan", a name suggestive of
speed. We found the allusion apt, as it seemed faster than some other high-end
desktop scanners we've tested recently, although scanning with it is still an
exercise in patience if you're used to the instant gratification of a digital
camera.
Prescans (to produce low-resolution views of the film being scanned, to assist
with cropping and color/tone adjustment) routinely took about 25 seconds. This
is about midrange among scanners we've tested, with some taking as little as
12 seconds to generate a preview, and others taking upwards of a minute when
their color management system was engaged. We generally found the prescan time
less of an issue with the SprintScan, as we didn't find a need to repeat prescans
very often while tweaking the scanning parameters.
For the scan itself, the SprintScan's processing involves five stages: Calibration,
scanning, rotation, color correction, and file saving. Rotation, color correcting,
and file saving will be very dependent on the computer the scanner is attached
to, but the calibration and scanning stages should be about the same regardless
of host. In our testing, we had the SprintScan connected to a slightly aging
PowerMac G3 433 MHz CPU, with 192 MB of RAM, and the scanning software running
in a 145 MB partition. We tested scanning speed with Polaroid's own PolaColor
software. Here are the times we measured for a maximum-resolution RGB scan of
our black/white resolution target film:
Scan Operation/Condition
|
Total
Time
|
Time for
Operation
|
| Preview |
25 s
|
25 s
|
| Calibration |
1m 4s
|
64 s
|
| Scanning |
2m 15s
|
71 s
|
| Rotation |
3m 7s
|
52 s
|
| Color Correction |
3m 38s
|
31 s
|
| File Saving |
3m 57s
|
19 s
|
We were surprised that calibration took as long as it did at the beginning of
each scan: This is pretty well a fixed time, regardless of how large a scan
you're doing. The scanning itself was quite fast, particularly given the size
of the files produced. Smaller scans are much faster: Our 1828 x 862 scan of
the Musicians slide took only 75 seconds in its entirety, including 52 seconds
for calibration. (No, we're not sure why calibration for that scan took 12 seconds
less than the time reported above for a maximum resolution image. There seemed
to be a good +/- 10% variation in the prescan times we saw with the unit.) You'll
note that rotation of the scanned image takes a fair while on larger files:
You may want to defer that operation to post-scan processing in Photoshop or
other imaging software, as in our experience, you'll likely want to open the
scans to retouch dust spots, make fine color adjustments, etc, as part of your
normal workflow. The Color Correction item in the table refers to PolaColor's
application of its IQA color management. This seems a good bit faster than other
color management schemes we've seen used on other scanners we've tested.
Scanning Results
For a full analysis of the results we obtained with the SprintScan 4000,
check our sample pictures page for it. - You'll find
a full analysis of each of our standard test scans there, as well as the sample
images themselves. For now, a brief summary of what we found:
As one of the very first 4000 dpi desktop scanners available, the SprintScan
4000 led the market by a good 18 to 24 months. With other 4000 dpi models now
becoming available, we were somewhat surprised by how well the SprintScan held
up to the current competition. Color was excellent, dynamic range very good,
and speed better than several more recent models. It was also notably easy to
use, either with Polaroid's own PolaColor scanning software, or the excellent
(but more prepress-oriented) SilverFast AI by LaserSoft.
We liked the SprintScan's speed, not only in the scanning, but in the workflow,
which seemed to require relatively little repetitive prescanning as we made
tonal and color adjustments. Scanning is still an exercise in patience (for
us at least), but the SprintScan made the process relatively painless.
The SprintScan showed its age slightly when it came to handling very dense slides,
as exemplified by our *very* dense "Train" image. Newer scanners with
14-bit A/D can reach a little further into the shadows, but not as far as we'd
have expected: The SprintScan acquitted itself surprisingly well on this very
tough test of dynamic range.
We were also very impressed with the SprintScan 4000's resolution. Not all 4000
dpi scanners are created equal, and the SprintScan showed some of the highest
resolution we've seen to date. (June, 2001) Its (apparently) fixed-focus optics
were also very sharp corner to corner. (We saw a little loss of definition in
film grain patterns in the extreme corners of the image, but image detail didn't
seem to suffer at all.)
Overall, we liked the SprintScan quite a bit. The only thing we'd like to see
significantly improved was its dust removal function. It apparently uses a purely
software-based approach that worked well on some subjects, and rather poorly
on others. Competing systems using a combination of hardware (IR imaging of
the dust and scratches, apart from the film emulsion itself) and software are
much more sure-footed in their operation.
There's a lot more to say about the details of the test scans we captured, and
we say it all on the sample pictures page. Check
it out. This is quite an impressive scanner, and a good deal to boot, at current
(2001) market prices.
The Bottom Line
Despite it's relative age in the marketplace, the SprintScan 4000 holds its
own quite well against the current crop of offerings. It appears to offer a
good price/value point between the latest "high end" desktop scanners,
and lower-priced models with lesser capabilities. The SprintScan offers excellent
scans, with good throughput and easy operation, at a competitive price.
Want more information on the scanner? Get it below!
Main - Software - Sample Pictures
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