fine prints in your digital darkroom
updated June 2, 2005
A scanner is a device that converts prints
or images on film— negatives or slides— to digital format, i.e., pixels
(picture elements). A scanner consists of a fixture for holding the film
or print, a light source, a CCD sensor, and associated electronics and
software. Either the film or the sensor moves.
To make prints digitally from film originals you'll need to have them
scanned. If you have a stock of existing film images I recommend
that you purchase a scanner. Although shops can make scans, you can usually
obtain the finest quality with your own scanner, and you may
save money in the long run. You don't need a scanner for images made on
a digital camera.
Your choice of format will be influenced by your existing equipment,
your goals, your budget, and hardware availability. I now do most of my
with a digital SLR, but I have a large collection of 35mm negatives and
slides dating back to the 1960s as well as a modest collection of
medium format negatives. My main scanner for
35mm is the 4000 dpi Canon CanoScan
FS4000US, but I still use the 2400 dpi 36 bit Hewlett-Packard
PhotoSmart S20 for panoramic images. It makes decent 13 inch high
(up to 33 inch long) prints. Dust can be a real pain with the HP, but the
CanoScan's infrared channel dust removal is very effective.
I use the Epson 3200 for medium
format and larger.
We begin with a description of scanner specifications, then we discuss
35mm, medium format and large format scanners, culminating with a large
of scanners. The use of scanners is described in a separate page, Scanning.
Here are the key film scanner specificationss. We refer to them below.
Resolution in pixels per inch (ppi), frequently called dots per
inch (dpi), though pixels is more accurate. Ranges from 1200 dpi for large
format flatbed scanners to 5400 dpi for the
Scan Elite 5400 (higher for a few drum and "virtual drum" scanners,
which are beyond the budgets of most consumers). This number specifies
maximum available optical resolution. You can usually select
a lower resolution, which saves time and storage, if you don't plan to
print large. Consider only optical
resolution, not interpolated resolution (often a larger number), which you can obtain in
image editing programs by resizing the image. True visual resolution in
line pairs per inch (or mm) tends to be proportional to dpi for dedicated
film scanners. More on the subject can be found in Understanding
image sharpness part 2. (You might want to start with the explanation
of MTF in part 1.) Inexpensive multipurpose
flatbed scanners such as the Epson
3200 are not as sharp as dedicated film scanners— a bit disappointing
because they're so versatile, but they are decent for medium format and
have a sweet spot for 4x5. The apparent
reason is that the lens has to cover a large area— usually
8.5 inches, unless the lens can be repositioned for the transparency unit. Excellent
technique— fine lenses, fine film, and sturdy support— is required to
take advantage of the higher resolution scanners.
many Pixels Per Inch (PPI) do you need?
|Print quality depends of the number of pixels per inch sent to the
printer. The following table gives a rough guideline relating printer PPI
to perceived print quality, assuming a sharp image. You can get away with
lower PPI in large prints because they tend to be viewed at greater distances.
These numbers are actual pixels per inch, not necessarily the dpi "resolution"
of the image file, which is actually a scaling factor. Print file size
and scaling are discussed in Pixels, images,
||Outstanding. As sharp
as most printers can print; about as sharp as the eye can see at normal
to 300 PPI for small prints, 8½x11 (or A4) and smaller.
Outstanding quality in large
prints, 11x17" (or A3) and larger, which tend to be viewed from greater
||OK for large prints.
Adequate, but not optimum, for small prints.
||Adequate, but not optimum,
for large prints. Mediocre for small prints.
I typically aim for at least 300 PPI in 5x7
inch or smaller prints, 220 PPI in 8½x11
(A4) prints, and 180 PPI in 11x17 (A3) or larger prints. Further discussion
on print resolution can be found in the page on Printers.
The following table relates 35mm scanner PPI to Print PPI (Scanner PPI/magnification)
for several print sizes. (A full frame 35mm image is 24x36
mm = 0.945x1.417 in.)
print size in inches (magnification)
Bottom line: 2400 PPI is
sufficient if you don't plan to print larger than 8½x11
inches (A4; Letter size); it's very good for11x17
(A3). 2900 PPI has a slight edge at 11x17
(A3). 4000 PPI is excellent for 13x19
and even 17x24.
I set my Canon FS4000US to 2000 PPI if I don't plan to print larger
than Letter size. This limits file size (which can be huge at 4000 PPI)
and speeds up scanning. If I plan to print A3 or larger I select maximum
Dmax: the dynamic range, i.e., the maximum film
density the scanner can respond to. Density is defined on a logarithmic
scale as log10(fraction of light transmitted through the film).
Dmax is typically between 3 (0.001 transmitted) for basic scanners and
4.8 (0.000016 transmitted) for premium scanners like the new Nikons.
Scans are often noisy in areas of slides or negatives where the density
is close to Dmax. You won't find much about scanner noise in manufacturer's
specifications— you'll have to read about it in reviews.
With certain scanners, VueScan
can scan images repeatedly and use a technique called signal averaging
to reduce noise. Slides are somewhat more sensitive to Dmax than negatives:
Dmax = 3.6 should be sufficient for almost any slide; Dmax = 3.2 is OK
for negatives and typical (but not all) slides.
Bit depth. The number of bits per pixel, typically between
30 and 42. Scanners represent images in RGB format, three colors per pixel,
so a 30-bit scanner has a 10-bit color depth (10 bits per color channel);
a 42-bit scanner has a 14-bit color depth, etc. The number of levels n
bits can represent is 2n: 10 bits represents 1024 levels;
14 bits represents 16384 levels. Most standard file formats store only
24 bits per pixel (8 bits per color channel; 256 levels), so they can't
take advantage of the full color depth of a scan— information is lost
when data is transferred out of the scanner. But you can retain all the
scan information by saving it or transferring it to your image editor as
a 48-bit file (16 bits per color channel; 65536 levels). When you do so,
the scanner information (typically fewer than 48 bits) is padded with zeros
to fill all 48 bits. I strongly recommend
doing this if you want the richest prints with the finest tonality. You'll
need an image editor that supports 48-bit files. Most don't; Photoshop
(the full version, 6.0+, but not Elements) has limited 48-bit support.
Window Pro has full 48-bit support.
TWAIN scanner interface. An industry standard
interface used by Windows to transfer graphic data from scanning devices
(flatbed scanners, digital cameras, etc.) directly into applications such
as editing programs that can use the data. If the scanner's TWAIN interface
and your image editor allow it, you can manipulate and save images in 48
bit color depth. Once you're finished manipulating the image, you may
save it as a 24 bit file without loss of quality.
Infrared (IR) channel dust removal. Some
scanners acquire a separate image with an infrared light beam in order
to detect the presence of dust, which responds differently to infrared
than it does to visible light. Spots on the main image are filled in by
interpolation. Works for all color films except Kodachrome. Does not work
for B&W. This can be a very nice feature— I've spent too many
hours removing dust spots from HP S20 scans with Picture
Window's excellent clone tool. IR dust removal goes by the acronyms
Digital ICE (Nikon and Minolta; a trademark of Applied
Science Fiction) and FARE (Canon).
If you don't own a scanner you can have images scanned to a Kodak
Photo CD: about 2200
pixels per inch (unimpressive) or 4400 pixels per inch (excellent)
for the Pro Photo CD. Dmax is 2.8-3.0
(unimpressive)— adequate for negatives but mediocre for slides. You are
limited to 24 bit color.
source. This important aspect of scanners is rarely mentioned
in the specs. As with enlargers (illustrated on the right), there are two
essential types: collimated, i.e., beamed (shown on the left
for a condenser enlarger) and diffuse (coming from all directions;
shown on the right for a diffusion enlarger). All flatbed scanners have
diffuse light sources; most dedicated film scanners have collimated light
sources, though they differ in the degree of collimation. A "point source"
would be 100% collimated.
Collimated light sources have higher contrast when used to scan (or
enlarge) Black & White film because silver grains scatter light. Since
most of the light entering the film is pointed towards the enlarging lens,
scattering causes a loss of light, hence an increase in contrast. This
contrast increase is known as the Callier effect. With diffusion
light sources, light is entering the film from all directions; as much
light is scattered towards the enlarging lens as is lost; hence there is
no increase in contrast. Collimated light sources tend to block highlights;
diffuse light sources have a longer tonal scale— they are generally preferred
for fine B&W printing. The light source has little effect of the contrast
of color images because color dyes don't scatter light.
There a persistent myth that diffusion light sources produce less sharp
and less grainy images than condenser light sources. Not so!
In my wet darkroom days I used a condenser enlarger for 35mm Black &
White and a diffusion enlarger (a color head) for medium format and color
images. The diffusion enlarger was every bit as sharp. If images from diffusion
light sources seem less grainy, it is because they are less contrasty.
Nevertheless, the myth may persist a while because inexpensive flatbed
scanners, which have diffusion light sources, tend to be less
sharp than dedicated film scanners. This is due to their optical systems:
lenses on inexpensive flatbed scanners must cover an 8½ wide
field; 35mm camera lenses only need to cover a 1.71 inch diagonal. The
problem is not the light source.
One indisputable advantage of diffusion light sources is that they
are less sensitive to film scratches and defects— small bumps and irregularities—
on the film surface (usually the backing). That is because scratches and
irregularities bend light; as much light is gained from a diffuse light
source as is lost. The price of this advantage is rather modest: diffusion
light sources are inefficient; only a small fraction of the light reaches
the enlarger lens (or the CCD).
Erik de Goederen of the Netherlands markets, the Scanhancer,
a device made of a special polymer resembling an ultrafine groundglass
screen, that diffuses the highly collimated light source in the Minolta
DiMAGE Scan Multi Pro. He claims significant advantages— lower grain and
smoother tonal gradations— even with color film. Check the site
for availability with newer scanners. I'd like to try one with my CanoScan
FS4000US. The Minolta
Scan Elite 5400 has a diffuser option, which could be more of an advantage
than its high scan PPI.
In the discussion that follows I omit some of the technical details
of individual scanners. You can find them in the scanner
Prices for decent (at least 2400 ppi) 35mm film scanners start around
$300. Fewer models are available in 2005 than in 2003. I particularly
liked the Hewlett-Packard
Photosmart S20, discontinued in 2002, because it could scan panoramic images (24
from my Hasselblad XPan in one pass. But dust could be a pain. Compared
to the inexpensive scanners (like the excellent Minolta Scan Dual IV)
the better scanners have higher resolution (4000 dpi or higher), higher
Dmax, and (hopefully) infrared dust removal. Images scanned at
2400-2900 dpi and properly
sharpened are about as sharp as conventional darkroom prints. 4000 ppi scanners are attractive because they can produce prints
sharper than conventional darkroom prints. I've analyzed
them in gory detail in
image sharpness Part 2.
In July 2001 I purchased the 4000 dpi Canon
FS4000US 35mm/APS film scanner. Scans have 42 bit precision with Dmax = 3.4 (4.2 in 42-bit
mode). Its highly effective FARE infrared channel dust removal (Canon's
version of ICE) has minimal effect on image sharpness. It scans more slowly
than the other 4000 dpi scanners, but its superior dust removal is likely
to make the total scan process faster than the Polaroid. Reviewed by Imaging-resource
(6/23/2001) and Taylor Hively.
Unfortunately the hardware doesn't support panoramic scans. According to
post, there were numerous manufacturing defects (excessive noise, black
dots, or "sootiness") in early samples. I heard less about defects in 2002.
As of 2005 the FS4000US has been discontinued. Today I'd choose one of the Nikon or Minolta scanners listed in the scanner
|July 22, 2001
I've put up a review of the Canon
CanoScan FS4000US 4000 dpi 35mm/APS film scanner.
Summary: Great hardware: very sharp images and excellent color. Effective
infrared dust removal. Software is mediocre, but adequate, especially if
you scan to16-bit B&W or 48-bit color files. Early samples had frequent
defects (mine is OK), a few of which may have resulted from easy-to-fix
line noise. I've heard that Canon's support is weak (I haven't needed
it). All-in-all an excellent product. Supported by Hamrick
flatbed scanners for 35mm, medium format, and 4x5 (inexpensive)
scan reflected images (prints) 8.5
inches wide and come with transparency units (TPU's) of various sizes in their covers to scan
film. $200 and up. They're great for historical photographs,
where negatives are seldom available, but they're not as sharp as dedicated
film scanners with comparable resolution, though they're improving. The reason: the lenses have to
cover an 8.5 inch wide field. 35mm camera lenses only have to cover the
1.71 inch diagonal of the 24x36 mm
frame. They're adequate for 35mm enlargements up to about 8½x11
inches, excellent for most medium format uses (sharp enlargements up to
13x19 inches), and outstanding for
4x5 and larger (sharp at 32x40
inches BIG), where they have
a real sweet spot. The transparency units have diffuse light sources that
reduce the ill effects of dust and scratches compared with the collimated
(directional) light sources in dedicated film scanners—a similar effect
can be observed when comparing diffusion enlargers (cold light and color
heads) to condenser enlargers.
format film scanners (expensive)
These scanners have 4000+ dpi, superb image sharpenss, and excellent Dmax. The top contender (and most widely available) is the 4000 dpi Nikon Super
Coolscan 9000 ED. Dmax =
4.8 (better than 4.2 in its predecessor, the 8000 ED). Very fast. ICE4
infrared dust removal and image enhancement. The 8000 ED was favorably
reviewed by Michael
Reichmann and Imaging-resource.com.
Hecker appreciates its ability to pull detail out of shadows. The pick
of the litter because it has infrared dust removal and true 4000
dpi resolution for medium format.
Epson Expression 1680
Professional (E1680-PRO) and Umax
PowerLook 1100 flatbed scanners can handle up to 8x10
inch film: they should be sufficient for tack sharp 48x60
inch prints. You'll need plenty of memory and storage. For large format
photography I recommend sites by Q.-Tuan
Luong and Paul Butzi.
reviews high-end scanners.
With digital cameras capturing most development effort,
progress in scanners has slowed, but Konica-Minolta
has some intriguing new models. Steve's Digicams has a list of scanner
links, which may be more up-to-date than the links here.
by format— alphabetical within each format. Discontinued models in small print/gray.
||USB/SCSI. Scans more slowly
than Nikon or Polaroid 4000 ppi scanners. See my
review, which links to other reviews. *Dmax = 4.2 in 42-bit mode;
3.4 in 24-bit mode.
Photosmart S20 (Discontinued)
||USB. Can scan panoramic
images. Discontinued in 2002.
DiMAGE Scan Dual IV
||USB 2.0. APS optional. Scan Dual III was reviewed favorably
Digicams. Excellent buy.
Scan Elite 5400
||"Grain dissolver" diffuses
the light source.
new product. Could be the top 35mm scanner as of mid-2003. The
5400 II (2005 model) doesn't seem to have the grain dissolver, which
was one of the attractions of the 5400. The 5400 is still on KM's
website, but it's getting hard to find. Photo-i
Coolscan V ED (LS-50
||4000 dpi, higher speed replacement
for the LS-IV ED (Oct. 2003). MSRP $600. An attractive
Super Coolscan 5000 ED (LS
||16-bit depth replacement
for the 4000 ED (Oct. 2003). USB 2.0. High speed scans. MSRP $1100.
|Microtek Artixscan 4000T
|| *Software dust removal is
less effective than IR. Apparent successor to Polaroid Sprintscan 4000(?) SCSI-2 interface. Polaroid reviewed by
See Ian Lyons'
|Microtek Artixscan 4000tf
|USB and Firewire. Includes Silverfast Ai 6.0 software and additional packages. Relatively fast scans (2 min @ 4000 dpi).
DiMAGE Scan Multi Pro
||Optional 16mm and Minox
holders. Dmax spec has met with some skepticism, but Imaging-resource.com
was pleased. Check out the Scanhancer,
which diffuses with light source, resulting
in reduced grain and smoother tones.
Super Coolscan 9000 ED (LS
up to 6x9
||Replacement for the 8000
ED (Oct. 2003). IEEE 1394. High-speed scanning. MSRP $2000. Will scan 35mm
panoramic images with an adaptor.
|Microtek Artixscan 120tf
||*Software dust removal. FireWire and SCSI-2. Includes Silverfast Ai 6.0 software and additional packages. Apparent successor to Polaroid Sprintscan 120(?)
|Imacon Flextight 343
||"Virtual" drum scanner.
IEEE 1394. Scans up to 6x18 cm (very nice for medium format panoramic images).
scanners can be extremely sharp because their lenses cover tiny areas.
||USB 2.0. Lower resolution
than dedicated film scanner; excellent for medium and large formats. I trust Epson scanners more. Scans
up to 8.5x11.7 inch reflected prints. UK
site. | Photo-i
||USB 2.0. Lower resolution
than dedicated film scanner; excellent for medium and large formats. Scans
up to 8.5x11.7 inch reflected prints. My
review | Photo-i
|Epson Perfection 4180
|35mm, medium format Flatbed
|Good budget choice for medium format film. Resolution may be better than the 3200. USB 2.0.
|Epson Perfection 4990
choice for medium and large format film. Resolution apparently
considerably better than the 3200. USB 2.0 and Firewire. Successor to the 4870, reviewed by George Nyman. Photo-i review
|Microtek ScanMaker i700
|Scans 8.5x14" (legal-size) reflective documents. USB 2.0, Firewire. Includes Silverfast SE 6.0. Why don't they specify Dmax?
|Microtek ScanMaker i900
|Scans 8.5x14" (legal-size) reflective documents. USB 2.0, Firewire.
|Epson 1680 (E1680-PRO)
||Comes in several versions.
Includes Silverfast Ai5 software. See photo.net
post. Difficult to justify now that 4990 is available.
||SCSI. 1450 has Firewire
for new PowerLook
270 with ICE.
|Imacon Flextight 848
||The gold standard. Lower
resolution for larger formats. "Virtual" drum scanner uses an actively-cooled
CCD. True drum scanners use photomultiplier tubes. Fast (100 MB/min)
|Imacon Flextight 646
||Slower than the 848 (40
MB/min.). CCD not actively cooled.
|Imacon Flextight Precision
||Virtual drum. Slower than
the 646 (20 MB/min.)
you are buying a scanner, you can help support this website by purchasing
it through Adorama, which offers competitive prices and excellent service.
Just click on the price, above.
|Flatbed scanners scan reflected
documents as well as film. All others are film-only ("dedicated" film scanners).
Flatbed scanners tend to be less sharp than dedicated film scanners because
their lenses have to cover larger fields— typically 8.5 inches wide. But recent models have improved significantly.
|MF (medium format) scanners
scan up to 6x9 cm.
|Most scanners with bit depth
greater than 24 (8 bits per color channel) can transfer 48 bit files (16
bits per color channel) to the image editor via the TWAIN
|Where two dpi numbers are
specified, e.g., 1200x2400, the lower number is the more significant. The
higher number is merely the stepper motor pitch.
The bottom line is that scanners are excellent and prices are dropping,
though change has slowed down now that manufacturers are concentrating
their efforts on digital cameras. You can make satisfying 13
x19 inch prints from 35mm negatives scanned at 2400 dpi (better
at 3200+ dpi), and you can make amazingly sharp prints— better than darkroom
prints— with a 4000 dpi scanner.
All the scanners I've mentioned provide excellent results when used
properly. It's more important to learn to use your scanner well than to
purchase the latest, greatest model. (This is true of most other equipment,
as well.) I discuss the use of scanners— how to get the most out of them—
in Making fine prints Part 2: Scanning.
Imaging Resource scanner
reviews The best overall source of scanner
reviews with excellent tutorials. Kept up-to-date.
Rockwell's Scanner Recommendations — a nice list, with opinions.
has some scanner reviews, well worth reading. This page also includes links
to film, printer and software reviews. Since it's hard to tell if they'll
keep it up, here are links to the Canon
film scanners and 10
Film Scanner Reviews More than you wanted to know, but
may not be up-to-date. His Filmscanners
List archive can be accessed by Thread,
or Search. It gets a
huge number of posts. Well worth looking at, but don't sign up for the
e-mail list unless you want an average of 40 e-mails a day.
Steve Hoffman's Nature and Scenic Photography
Good information on HP and Nikon scanners.
regarded inexpensive scanner software which works on most film scanners.
Updated frequently. I use it for panoramic scans with the HP
post has some tips and a comparison with SilverFast.
software. More professional, flexible and expensive than VueScan.
Scanning tips by Wayne Fulton. Covers
flatbed and film scanners.
Primer on Image Histograms and Curves— How to scan by Dane Kosaka.
Photo.net's forum on scanning
(a geek's delight with over 400 threads) and scanner
Extremely informative site, in Deutsch. Worth translating.
and text copyright © 2000-2013 by Norman
Norman Koren lives in Boulder, Colorado, founded Imatest LLC in 2004, previously worked on magnetic recording technology. He has been involved with photography since 1964.