I recently received a question from
a Quick Tips reader regarding 4" x 5" transparencies
and 35mm transparencies.
Here are the rules of thumb as I understand
- The better the initial quality
of a photographic image, the better the scanned and printed
image will be. Each step in the process removes more image
"information" (color information, detail, etc.),
so start with the best possible original.
- Transparencies hold more detail
in a wider tonal range (from darkest darks to lightest
lights) with more saturated colors than does reflective
art (photographic prints). This means that what you see
on the press sheet more closely resembles the original
- The larger the transparency,
the better. A 4" x 5" transparency will contain
more detail to begin with than will a 35mm transparency.
It will also need to be enlarged less than a 35mm transparency.
Therefore, for a final poster-size image you would ideally
want to start with a 4" x 5" image to retain
the greatest tonal range, most faithful and saturated
colors, and most intricate detail of surface textures
in the photograph.
- Cameras that use 4"
x 5" film are bulkier and far more expensive than
35mm cameras. Therefore, fewer people can afford them
and they are less likely to be used for informal photo
opportunities. Most people who want to use a 4" x
5" camera will rent it (along with special lighting
equipment) for a specific (and stationary) photo shoot.
Most people will not rent one to take photos of a political
rally, for instance.
- Dedicated 35mm transparency
scanners, such as the Nikon CoolScan, were all the rage
when I was an art director five years ago. These scanners,
while not quite the quality of drum scanners (their ultra-expensive,
ultra-high-quality predecessors), were affordable and
quite adequate for scanning 35mm transparencies for print
publications. They also scanned film at a much higher
resolution than flatbed scanners scanned prints (since
the scanned 35mm transparencies needed to be dramatically
- Now, special transparency adapters
can be purchased for flatbed scanners (which have also
improved dramatically over the last several years). In
this case one could buy a single, moderately-priced scanner
for scanning both reflective and transmissive art.
Enlarging Scans -- REVISTED
#20 of Quick Tips was devoted to upsampling in Photoshop
(or other image-editing software), I strongly urged readers
not to scan a photo and then enlarge it. I wrote that when
you scan a photo, the computer captures the image in a grid
of squares that can be made larger or smaller by enlarging
or reducing the photo, but that you have the same number
of squares after you have enlarged the photo, and hence,
these squares become visible and soft or fuzzy, reducing
detail in the photo.
This is true. However, it only refers
to the file once you have scanned it at the usual 1.5 to
2 times the line screen.
If you want to enlarge a photo without
loss of detail, use the following formula to determine your
correct scanning resolution:
- multiply the print screen frequency
by1.5-2.0, then multiply the result by the enlargement
- for example, if you want to enlarge
an image 300 percent for a final 150 lpi screen, scan
it at 675 to 900 dpi: [(150 lpi x 1.5 or 2) x 3]=a final
scan of 675 to 900 dpi.
When you enlarge this 675 to 900 dpi
image 300 percent, the resulting larger image will be 225
to 300 dpi: a perfectly acceptable resolution. Remember,
enlarging an image reduces its resolution (from 900 to 300
dpi) just as reducing an image increases its resolution.
[Steven Waxman is a printing consultant. He teaches corporations how to save money buying printing, brokers printing services, and teaches prepress techniques. Steven has been in the printing industry for thirty-three years working as a writer, editor, print buyer, photographer, graphic designer, art director, and production manager.]