Hi potential digital bird-photographers,
In this part I will discuss scanners.
Most people who have made a reasonable investment in a good quality 35 mm SLR
camera and lenses for
bird-photography (especially if the equipment is relatively new and works well)
will be reluctant to
'convert' to digital even if the lenses can still be used with the new camera
body. The boxes full
of prints and slides (some of which will even be quite good photos) will haunt
the conscience and
there will be a feeling that a lot of time and effort will have been wasted if
the film medium is
'abandoned'
In such cases, an alternative to a Digital Camera and also as a 'simple' way of
'digitising'
existing prints and slides would be a scanner.
This would allow the photographer to continue to use his/her existing
photographic gear without the
need to go through another learning curve with a new camera. It would also
provide the capability to
store copies of existing prints and slides electronically thus providing a
greater range of
potential uses for the images.
Once the film versions of the images have been digitised they will be in
exactly the same form as
the images obtained using a digital camera.
Often the bird which is the intended subject of the photo is actually quite
small in the photo but a
good quality film photo (slide, print or negative) scanned with a good quality
scanner can be
'cropped' (the unnecessary bits around the subject cut away) so that the
subject becomes more
prominent. The 'new' image can then be printed on a good photo-quality printer
to produce a new
'masterpiece'. Or the digital version can be viewed on a PC or TV or used on a
web-page.
Types of Scanners:
There are two types of interest to the home/non-commercial user:
- Flatbed: Used mainly for scanning photo-prints. Most computer users will be
familiar with what
these look like. They are quite common, reasonably cheap and there is a large
range of models.
Don't be too concerned at the different types of 'technology' used in the
scanning 'head'. The LIDE
system used in some of the Canon models is probably more for reducing the
physical size of the
scanner than for scanning quality. This system may also use slightly less power
but power used by
these scanners in general is not a problem except that some models draw power
from the computer via
the USB port while most will require a mains power outlet.
When checking the specifications for scanning resolution, only look at the
'Optical Resolution' and
ignore the 'Interpolation Resolution'. Interpolation is obtained through
software tricks which can
produce an inferior result.
For scanning photo-prints an optical scanning resolution of 600 dpi (dots per
inch) will be
satisfactory if the intended purpose is to show the images on a web-page or
printed as snap-shot
size prints. To enable printing of larger prints it would be better to use a
scanner with a scanning
resolution of 1200 dpi. Many flatbed scanners on the market these days will
scan at these
resolutions. It is tempting to scan at the highest resolution possible but that
is not necessarily a
good idea. The higher the scanning resolution of a particular photo the larger
the digital data file
produced. It is quite easy to produce image data files of well over 50 Mb which
can become extremely
difficult, if not impossible, to handle on some home computers. These high
scanning resolutions will
not necessarily produce a better 'scan' but will produce huge images when
viewed at full size on a
computer screen.
Some flatbed scanners are equipped with a 'film adapter' which allows scanning
of slides and print
negatives.
Scanning slides and negatives requires very high scanning resolutions (high
dpi) due to the very
small area of the film frame so it is necessary to use a scanner with a high
scanning resolution.
Optical scanning resolutions of over 2000 dpi are needed and something around
3000 dpi is
preferable. Although some of the latest flatbed scanners with film adapters
seem to be capable of
producing acceptable results a different type of scanner is the answer for
slides and negatives
- Slide/Film scanners:
These are dedicated scanners usually capable only of scanning slides or film
negatives.
Some film scanners will only accept 35 mm slides or film while others can also
handle Medium Format
film and APS film using adapters. Some film scanners will only accept film or
mounted slides using
special adapters and some units can scan uncut rolls of film.
Film scanners can cost 4 or 5 times that of a flatbed scanner.
An important specification for film scanners is 'Dynamic Range'. This
determines the ability of the
scanner to successfully scan dark or dense slides and negatives.
A Dynamic Range (DR) of at least 3.6 is desirable. Be wary of scanners that
don't list the DR in
their specification sheet.
("Dynamic Range" is not a definite factor and may be calculated differently by
different
manufactures so use the figure as a 'reference' only.)
Kodachrome slides have a different 'construction' to other types of slides and
can be difficult for
some less sophisticated scanners to handle.
Ensure that the film scanner you are considering has a specific setting for
scanning Kodachrome
slides.
Drawbacks with scanners?
- There is a learning curve but probably not as great as with some digital
cameras;
- Scanning is a relatively slow process. Very high resolution scans involve
very large amounts of
data meaning that individual scans can take the best part of a minute each.
This means that scanning a large number of slides or negatives can be very time
consuming just to
get the images stored on the computer hard drive.
- While it is usually possible to scan most prints on a flatbed scanner not all
slides or negatives
are suitable for scanning. Prints using paper with a rough surface may be hard
to scan accurately
while images scanned from magazine pictures may have coloured lines (moiré
patterns) on them. Good
scanners usually have settings to minimise moiré patterns.
Very dark or dense slides and negatives may be difficult to scan ending up with
very dark electronic
images with little detail in the 'shadows'. It is difficult to tell if a
particular slide will scan
successfully by simply looking at it with a viewer. The slide may 'work' in one
scanner model and
not in others.
- Most scanners, flatbed or film, while struggle to accurately reproduce the
exact colours in the
original photo. Much of this can be corrected in good image software but my
experience has been that
the final result is rarely as good as the original.
- It is possible that, because slides are not dead flat, the scanner 'head' may
have difficulty
accurately focusing on the surface of the slide. Good film scanners have a
'manual' focus facility
but it would be rare on a flatbed scanner using a film adapter.
(Digital images have a distinct advantage here because the image sensor is
perfectly flat over its
whole surface thus producing an image which has the same focus across the
entire frame.)
- It is difficult to find a retailer with any film scanners in stock let alone
a range of different
models.
- Most of the latest scanners (particularly film scanners) require a USB
connection so a computer
upgrade may be needed. A large amount of computer memory (RAM) is also a good
idea, at least 128 MB.
(Some very high performance film scanners may require a Firewire connection.)
Scanner advantages:
- Digital imaging without resorting to a Digital Camera.
- Digital copies of existing prints, slides and negatives can be created.
- You might be the first one in the street to have a film scanner.
So ends Part 2,
Next time I will discuss Bird-photography and Consumer Type Digital Cameras (I
hope).
Cheers
Bob Inglis
Woody Point
Queensland
Australia
http://users.tpg.com.au/inglisrc/
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