| What went well -
and why? But first, let us
examine why we had success in the example above, where so many
appear to have failed or given up as judged from a search on the
web. So, we shall take a closer look at the steps 1-5 in the
example: |
| |
| 1.1 |
The set-up.
Here the critical elements are |
|
| |
a. Light
source |
Needless to say you need a uniform back-light. In my
home-built setup I use a sheet of pure white plastic cut from an
ice cream box as "primary diffuser" and (sometimes) a
"secondary" pure grey diffuser from an old slide viewer (Agfa
Gucki) of the hand-held eye-piece type.
You must also consider the colour
temperature of your light source. In the picture above you
can see that I have used a simple (and VERY cheap) 4.5 Volt
7-lead lamp. This provides, what we normally call a "cool"
bluish light, but in a physical terminology, this light source
has a high colour temperature. I also use a 12 Volt 30 Watt
halogen lamp with some success, but mostly with a bluish glass
as "secondary" colour filter. The reddish light from a tungsten
lamp (we call it "warm", but the colour temperature is low) will
increase your troubles in balancing the colour levels because
negatives (usually) have the so-called orange mask that provides
negatives with their distinct reddish hue. (See also below).
Important to know is also that some lamps only emit light in a
few, discrete wavelengths as is the case for modern
energy-saving bulbs, fluorescent tubes and LEDs. Tungsten lamps
have a continuous spectrum but a strong bias towards the red
light. Your light source should emit light that is well
represented at the reddish, greenish and bluish
wavelengths. If you use daylight as source, you should go for
the scattered light from the blue sky away from
the (reddish) sun or, even better, the scattered light
from a slightly overcast but bright sky, (even higher colour
temperature).
To the left, I have inserted a
picture of my back-lit "primary diffuser" together with
histograms for all colours combined (Master) and each of the primary colours,
red, green and blue. (distribution
of levels, 0....255, over all pixels). As you see there is a
fairly even distribution of all colours emitted by my rather
primitive LED source. And
as practical experience has shown us in 5. above this suffices
to bring our "digital negative" into a manageable area for
further balancing and possible additional enhancements. |
| |
 |
 |
 |
 |
|
|
|
| |
b. Optics |
|
| |
|
If you
use a compact camera with non-interchangeable lens you will need
something "extra" to have your negative fill out the whole field
of view in the horizontal dimension. Some cameras come with a
macro or super-macro mode that will do the job for you right
away, but take care: Some cameras do show a lot of distortion in
macro-mode that you do not notice when you shoot an occasional
small flower or insect but which may become very obvious and
annoying when your subject is a whole building, landscape or
similar. Try it out ! For
my current compact cameras, I use either a 135 mm telephoto lens or an
80 mm lens from a slide projector as macro front lens.
Both are from around 1950 found on flee markets (and thus,
cheap). These were designed to provide large magnifications
without distortion and without false colour fringes and they
work in fact very well in my set-up. However, in order to avoid
excessive vignetting your compact camera must have a good zoom - again,
without distortions. DSLRs
have now become within reach (financially speaking) for
more amateurs, and such cameras can of course also be used for
this type of work. An example of how one may set-up a DSLR for
film and slide duplication is presented on the
Diaposítive Duplication Page, |
| |
|
|
| |
c. Camera
controls and settings |
|
| |
Olympus Remote
Control RM-1
(How can any amateur
photographer live
happily without such
a handy gadget?) |
You
will want a camera that reproduces as faithfully as at all
possible all the levels recorded in your original film. This
means that you do not want automatic, aggressive
post-processing. The post-processing must be done in
sufficiently sophisticated digital imaging software. You may
also refer to the
Gallery Page for a slightly extended discussion on this
subject.
Usually, you
camera will do very well using the AUTO setting, but in
difficult cases with very contrast images, under- or over
exposed pictures and similar, the automatics of your camera may
fail and full, manual control is in general most
desirable. This is more so, as you may stop down your lens
(to a higher f-number) in order to increase the sharpness in
depth and thus, counteract smaller focusing problems.
In the set-up above, I have a
high colour temperature but a low intensity light source,
meaning
that I need quite long exposure times. As mentioned above, I
also prefer to stop down the lens and therefore, the camera must
allow for long exposure time settings. I may need as much
as 8 seconds of exposure time.
When you want to shoot a lot of
pictures in the minimum of time. Here a remote control
comes in truly helpful. Unfortunately, it appears that the trend
is away from that useful gadget for compact cameras. If you
don't have and cannot find a camera with this capability, you
must rely on the self-timer which almost each and every
camera has today. If not, find another camera.
Finally, if you want to shoot
many pictures during a good evening's work, you should consider
buying an external power supply for your camera. You will be
using the LCD display constantly for a long period of time and
that will drain your batteries |
| |
|
|
| |
d. The
mount and light board |
|
| |
|
Nothing
much to say her. Your own imagination and parts readily
available control the design.
It should obviously not be too
flimsy; with camera and extra lens it carries quite some load
and - as in my case - long exposure times are often required. I
built mine from the sliding rails for a drawer, available at the
local lumber yard and parts from an oooold office desk lamp.
|
|
2.2 |
The negative |
|
|
|
Original negative
(1991)
shot on Pertutz PR
100 |
Most negative film
(but not all) have a layer of dye that when developed has a
distinct reddish hue - this is the notorious orange mask.
It is there to counteract inevitable impurities in the other
colour sensitive layers of dye on the film. However, common to
widespread belief, the orange mask is NOT the main problem in
digital reproduction of negatives.
The orange mask is a monochrome
colour and therefore, in principle, we just need one filter to
remove its effects. In the wet darkroom we do this by means of
coloured glass or gelatine filters - in theory just one filter
for one specific brand (and batch) of film. In the wet darkroom
we further use optical filters to compensate for colour casts
(from different light sources) and simply to enhance certain
colours to make the scene look "right" in the final picture.
In the digital darkroom we do the
same. We use digital filters. More about that in paragraph 5
below.
The main problem with analogue
film reproduction is that it is so good in respect of definition
(speaking for negative film at least) while 8-bit digital colour
pictures may have difficulties in reaching that same definition
- and when it does, the "raw" pictures may look terribly wrong
to our eyes. Again, the answer lies in the digital processing -
not implemented as a standard algorithm within the camera but as
a dedicated piece of work in the digital darkroom.
Needless to say, the limitations
in definition implies that you can never "improve" upon an
analogue picture through digital copying. But, as we shall see
at a later stage, there may be details in the analogue picture
that are not readily seen by the human eye but which may be made
visible after proper digital image processing. |
|
|
|
|
| 3.1 |
Rotating and
Cropping |
|
| |
|
Noting much to add
here. You should just go for software that allows for easy
alignment through rotation using horizontal and
vertical lines plus free rotation at any arbitrary angle.
(That will also help you "save" pictures, where you have tilted
the camera by accident during exposure).
Regarding cropping, just make sure
that you software has easy settings for cropping to standard
formats such as digital cameras (4:3) and standard photos
(9:6) etc. |
| |
|
|
| 4.1 |
Inverting |
|
| |
|
This is as simple
as can be. Any software that can invert colours (and most
programs can) will do that in one and the same way. Maybe some
have given up already at this stage? The pictures
bluish-greenish cast could be even worse had I used another
light source or had I used an indoor picture as example. But if
you have understood a bit of the foregoing remarks on film,
definition and levels, there is good reason to proceed. |
| |
|
|
|
5.1 |
Fixing and
Balancing |
|
|
|
INVERTED "ORIGINAL"
AUTO-LEVEL |
Most
digital imaging software packages come with a suite of automatic
operations for "enhancement" of your digital images. At the
outset, you should treat these AUTO-FUNCTIONS with the
utmost suspicion. It is as with the processing algorithms hidden
inside your camera: They make some generalized assumptions based
upon the contents (distribution of levels) of your image and
then proceed with a number of standard operations en suite
(mostly hidden to the user) trying to achieve what the designer
of the software thought you would like to see as the final
result. These standard functions may work well (sometimes) on
slightly unfocused, slightly underexposed, slightly colour cast
indoor pictures from aunt Audrey's 80 year birthday party (but
sometimes they may also produce disastrous results !).
However, they were not designed
for and nor do they normally work with such special applications
as for example analogue film copying where the distribution of
colour levels together with colour cast and white balance may
differ substantially from what the software developer would
think should apply for a digital photo taken under "normal"
instances.
As an example, I show again the
final picture from 5 (where I used AUTO-INVERT). Below, I have
inserted similar results for the inverted negative in 4., using
AUTO-ENHANCE, AUTO-COLOUR and AUTO-CONTRAST, as available and
named in PhotoImpact 12. Other brands should provide similar
functionalities.
Obviously, only AUTO-LEVEL works
(at least for this picture). The others do not - and in other
cases may decidedly degrade the picture even further. The answer
is, (or so, I think), that AUTO-ENHANCE/ -COLOUR/ -CONTRAST have
built-in assumptions as to what may need improvement in an
ordinary digital picture and apply a number of modifications in
a fixed, consecutive row. That simply doesn't work for the kind
of imbalance in colour levels that we encounter here. You very
rarely see this kind of blue-green cast in everyday photos !
The AUTO-LEVEL on the other hand
is far more "clean". It only makes one specific assumption about
the distribution and balance of the levels of colours that are
already present in the picture and stretches the distribution of
colour levels over the entire range in a more useful way.
How this is done in detail and
why it works so well so often (at least in PhotoImpact), I
cannot say. The assumptions on how to re-distribute the colours
may be different in other software but here at least, it is a
very useful application that may sometimes just do the job and,
if not, point to what other routes for fixing that should be
pursued.
|
| |
| |
|
|
|
AUTO-ENHANCE |
AUTO-COLOUR |
AUTO-CONTRAST |
|
| |
|
| |
Should everything fail - and it so
does from time to time - we are still on the right track and
there are still additional (manual) means for reaching useable results
and also for giving your picture that final, finishing touch.
Things typically go sour for negatives taken on daylight film in
artificial light; in extreme contrast scenes or under lightening
conditions that produce severe colour cast.
In such events one will have
to resort to additional techniques such as White Balance, Curves
& Levels, Colour Cast and more. There are no text-book
solutions, but problems in these instances are more or less the
same as with less properly exposed or slightly deteriorated
colour diapositives so, there will be some
guidelines/inspiration to find if you vistit the following
Diaposítive Duplication Page, |
|
