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The interpretation of these findings turns out to be difficult. The mea-
Surements taken with Gretag D 33 and Macbeth TD-100 point to the fact that
the measured densities over the whole range of density are weighted non-
-linear. It seems that the receiver of the Optronics P-1700 also has such
a non-linear response. However, the result yielded with the {High Defini-
tion Film can not be explained unambigously. Similar problems poses the
interpretation of the measurements taken with the Macbeth TD-102 and the
Joyce-Loebl 3CS. The partly unsystematical behaviour of these instruments
is probably caused by their illumination equipment and by the influence
ANS, PH2.19.
Scattering light probably causes the significant differences (fig.6)
following from measurements taken with the Macbeth TD-100 equipped with
three different apertures. The variations between the aluminium apertures
of 0.8 mm and 3 mm are as evident with all the other sorts of film. The
black aperture was only used for measuring the calibrated Kodak step
wedge.
AD
+ 0.10 2 3
+ 0.05
e
1.0 2.0 diffuse density
optische Dichte
Fig.6: Diagram of corrections (like in fig.5) of Kodak photographic
step tablet no.3 (calibrated) and Macbeth TD-100, newly adjusted (9
for each measurement at D = 0.00-and D = 2.76.
Curve 1: aperture 0.8 mm (aluminium); curve 2: aperture 3 mm :
(aluminium); curve 3: aperture 0.8 mm (black).
With the Macbeth TD-102 and the Gretag D 33 no influence can be noticed
as to the use of different apertures. Here the maximal deviations
amount to 0.02 D, in the mean less than 0.01 D. This corresponds with
the measuring accuracy of these densitometers.
À change of the aperture is equivalent to a change of the pixel size
with the Optronics P-1700. Fig.Ta shows the difference between pixel
sizes of 25 um and 100 um of three selected films. The emulsion is
towards the receiver. Like the Plus-X the film samples of Tri=%, IF 242)
and Aviphot Pan 30 (not graphed in fig.Ta) reveal very similar variations.
Reversing the samples so that the emulsion is now towards the condensing
