Photographing carbonized papyri fragments is almost a science of
its own. The most important variables affecting the production from
the original to paper copies are:
To search the best ways to produce photographed pictures,
we went through several variations. We concentrated on
illumination conditions, film material, filters and exposure times.
- Film material
- Exposure time
- Camera, lenses, apertures, filters, focusing.
- Developing negatives:
- Development time
- Developer temperature
- Motion of development tank during development
- Producing paper copies:
- Contrast grade of paper
- Projector's light source
- Development time
Optimal lightning conditions are essential
for succesfull photography, especially in our case of an extremely
dark object. A set of variables and restrictions define the limits
and possibilities of illumination:
There is one limitation compared to direct physical study:
the normal of the plate should point to the camera; i.e. if the
plate is at an angle with it, some of the photographed areas
may not be in focus. With a studio camera, the plate can
be photographed also in a sligthly tilted position.
When studied with the naked eye, the plate can be held at hand
and examined from almost any angle. The human eye is also
somewhat capable to reduce, or omit, the disturbing direct
Experience shows that the readability of the writing seems to be
best when the
reflection of the light source is just on top of the text. Further
tests emphasis this observation, and it seems that the readability
varies according to the angular distance from the reflection line.
at a straight angle, the light source would be directly behind
(or in front of) the viewer. Naturally, the reflection itself
cannot be allowed to be in the picture. The optimal angle
for a single light source can be found by moving the source
so that the reflection just goes out of the picture boundary.
With several light sources, symmetrically set at the
optimal angle, a nearly uniform light field can be created.
A large, ring-shaped light source could be nearly optimal.
Use of diffuse filters or plane reflectors may further help
to hide the reflections and improve the uniformity.
The contrast between the script and the background depends
directly on the brightness of the lamps. The more light,
the better the picture. Unluckily the black fragments
absorb light very efficiently, and thereby heat up quickly.
Heat erodes the pieces, so one must not expose the fragments
to intense light for too long.
Tungsten light bulbs emit a wide range of electromagnetic
radiation. Infrared films as Konica 750 or Kodak HiE are actually
not sensitive to infrared radiation (from about 1000nm to
12000nm). Their sensitivity
range has been extended from the normal visible light (400-600nm)
to near-infrared, around 750nm. The typical spectrum of a
tungsten bulb is a continuous, roughly bell-shaped curve, extending
from below 400nm to over 1000nm.
The spectrum of halogen light sources is weighted more in
the shorter wavelength band, and therefore seems not as usable.
Fluorescent light consists
only of a few wavelengths, as shown in picture .
Because the fluorescent light sources produce a lot of
light with very little heating, they cannot be completely omitted,
but particularly for red-extended films, they are
utterly unsuitable. In ultraviolet light the writing
vanishes completely. So, this verifies the dependency between the
relative reflectance and wavelength, presented in figures  and ,
in the shorter wavelength band.
The infrared radiators, on the other
hand, produce too long wavelengths, beyond the sensitivities of
red-extended films and transparency of the glass.
- The placement of light sources
- The brightness of light sources
- The number of light sources
- The uniformity of light field
- Use of plane reflectors and diffusion filters
- Light source types:
The following film materials were tested:
Many other companies, like Agfa, manufacture similar
film materials. These films were chosen to compare
different film types, not companies. Technical Pan
is a high-contrast B&W negative, T-Max a standard,
high-resolution B&W negative, HiE and K750 are
red-extended B&W negatives and EPT is a color film.
The pictures were taken with an SMC-Pentax M camera, using
a Pentax 1:2 85mm lens with 12mm macro adapter.
The distance between the film and the papyri fragments
was 50cm. Three tungsten lamps was used as light
sources symmetrically around the plate, near the camera.
With 160 ASA as supposed sensitivity of film and using 1:2 lens,
our Gossen Lunasix III gave 1/60 for exposure time and 8
for aperture, measured from a standard grey card.
For black, carbonized papyri, strong overexposure is needed.
Table 2 lists the exposure times and apeertures we used
in the best photographs along with the film sensitivities.
Without the macro adapter, the exposure times could
have been halved. The ASA value is a rough estimate
of the overall sensitivity, from the manufacturer.
The IR filter used was equal to Kodak's Wratten 89B.
- Konica 750 Infrared
- Kodak High Speed Infrared 135 (HiE)
- Kodak T-Max 100
- Kodak Technical Pan
- Kodak EPT 160T (colour positive)
Film ASA Aperture Exposure Time (s)
Konica 750 32 8 1
Konica 750, IR filter 16 8 2
Kodak HiE 200 8 1/30
Kodak HiE, IR filter 125 8 1/15
Kodak T-Max 100 100 8 1/8
Kodak Technical Pan 100 8 1/8
We developed the negatives with Kodak's D76 standard developer,
shaking the developer container for 5 seconds every 30 seconds.
The temperature of the developer was 20.0° C. The development
times for the black&white negatives are given in table 2.
Film Time (minutes)
Konica 750 7
Kodak HiE 11
Kodak T-Max 100 (check)
Kodak TP 12
Development times for negatives with D76, 20.0° C
The paper copies were made with an Axomat projector with
EL-Nikkor 50mm 1:2.8 lens, aperture 8. We tried contrast grades
of 3, 4 and 5 (Agfa Brovira-Speed BH-310 papers RC 3,4,5).
Number 3 is the standard paper, and 4 and 5 have higher
The developer was Kodak's --, kept at 20.0° C.
The papers copies were adhered for 15 minutes, and then
kept under cool, flowing water for an hour.
Technical Pan is a very high-contrast film, and with
grade 5 paper the resulting image is almost binary, containing
only black and white, no shades of grey. If it were possible
to separate the writing from the background only by
thresholding with a certain grey shade, it could be done with
this combination of high-contrast film and paper. Unluckily
parts of the background are as dark as the characters, and
the extreme contrast causes the dark background to merge with
the characters, or parts of characters to vanish, depending
on the exposure. The writing is quite readable from the
best photographs, but it is also clear that much of the
details of the original fragments is lost.
The color information of the EPT 160 film didn't seem to
be of much help. There is really not so much color
in the original fragments, and the measurements of the
spectra show that there is no single peak in the contrast
in any bandwidth (color). Still, the idea of using color
should not be completely discarded, because in some of the
carbonized fragments the background is still yellowish,
and that information could be of use. One can use filters
with black and white film to restrict the bandwidth between
certain wavelengths, but from color film, one can roughly
filter out unneeded wavelengths afterwards.
To produce a smooth, low-contrast and high-resolution
grey scale image one should choose Tmax film and
use a grade 2 or 1 paper. The resulting contrast
is then so low (with grade 3 paper the outcome is
near the real contrast - a very low one)
that large magnification is needed to increase
the readability to an acceptable level.
Enhanhing the Tmax's contrast with a grade 4 or 5
paper gave quite good results. The resolution
was good, background details were still visible
and the contrast between the writing and
background was enhanced.
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Antti Nurminen, 34044T, email@example.com