3. THE NEW MULTISPECTRAL CAMERA MK-4 
The MK-4 camera consists of 4 equal similar camera bodies 
coupled together. One of them in general is loaded by a 
two-layer sensibilized colour ("spectrozonal" ) f ilm and 
the three others by black-and-white films and differing 
spectral filters according the spectral bands given in 
table 1. In this way the MK-4 allows to produce in a 
unique matter two types of colour represention for image 
interpretation: 
a) the mu 1tispectral colour composition 
b) the spectrozonal colour version. 
The camera is equiped with a forward motion compensation. 
The stereoscopic overlap is eligible between 20 and 80 %, 
the exposion time is adjustable in 7 steps between 0.04 
and 0.005 sec. 
In the following the first results of the preliminary 
evaluation of a MK-4 photograph taken during one of the 
first experimental flights on 17.8.1988 14.51 GMT are 
given. This photograph (figure 3) shows an area at the 
Portuguese Atlantic coast with the capital Lisboa on the 
Tejo bay. The coverage ist 120 x 120 km 2 . Figure 4 is a 
12,5 times enlargement of a section from the multispec- 
tral image in the red band. It shows the structure of the 
town Lisboa, the suspension bridge with 2 piers, the hat— 
bour sites on the Tajo bay with heavy water pollution and 
other details. It es evident that all of the following 
results of image evaluation demand a confirmation in a 
generalized way. 
a) Quality of images: 
- Edge contrast and geometric resolution are different 
in the various spectral bands (maximum in the red band, 
minimum in the NIR) 
- the multispectral composite shows a better image 
quality, contrast and colour differentiation than the 
spectrozonal colour image 
- the individual multispectral images shows differences 
with each other in the position of identical ground 
points (relative distorsion between the multispectral 
channels). 
b) Geometric properties: 
- mean scale: 1:655 000, actual altitude: 196.4 km 
- geometric resolution for objects with "real" contrast 
(1,6:1) in the red band (635 - 690 nm) < 10 m, i. e. 
65 line pairs/mm