STATE-OF-THE-ART OF CLOSE-RANGE PHOTOGRAMMETRY 
and!5, and Peczek?®, These tables also con- 
tain information on the main characteristics of 
the more than 30 types of cameras. The focal 
lengths vary from 56 to 190 mm, the formats 
from 55-x-55 mm to 130x-180 mm, the cone 
angles from 33 to 88 gon, the aperature values 
from 3.5 to 64, and the exposure times from B 
to 1/500 sec. There is thus a fairly wide vari- 
ety oftypes available to the photogrammme- 
trist. A dominant feature of metric cameras is 
that the radial distortion is so small that it 
often may be neglected for most practical ap- 
plications. This has been a lens design criter- 
ion that, together with stability require- 
ments, has ended in the fixed-focus cameras. 
Only during the latest decade has it been 
possible to design and produce focusable 
lenses with radial distortions and stability 
within the photogrammetric tolerances. The 
Zeiss Jena UMK has two types of lenses, one 
for the shorter and one for the longer, focus- 
ing distances. This development is wel- 
comed because it opens the doors to many 
new applications of close-range photogram- 
metry. Because object size and accuracy re- 
quirements vary considerably, a great deal of 
flexibility is needed to obtain an optimal 
camera-to-object geometry. 
A few new metric cameras have appeared 
during the last few years, for example, from 
the USA (DBA Systems Inc.), and Japan 
(Sokkisha). The European manufacturers 
primarily have developed a series of acces- 
sories for both cameras and plotting machines 
which provide the photogrammetrist with an 
instrumental system well-suited to certain 
applications such as, for example, architec- 
tural photogrammetry. The possibility of tilt- 
ing the cameras (both single and stereomet- 
ric) by predetermined angles is a common 
feature. This also means a standardization of 
the geometry during photography, speeds up 
the field procedure, and decreases the risk of 
blunders, compared to the type of cameras 
that have continuous tilt facility. This must be 
regarded as an advantage for routine work 
with a standardised production. On the other 
hand the flexibility of the phototheodolites 
and the cameras placed on theodolites is 
often necessary in order to have an optimal 
location and direction of the cameras when 
the object, its environment, and other condi- 
tions make it difficult or even impossible to 
use standardised methods. 
Most of the available metric cameras are 
designed for the use of glass plates as the 
photograhic emulsion base. This is, of course, 
the best solution possible from the point of 
view of stability. This also provides a defined 
standard of flatness when treated in the pro- 
73 
per way, and with the use of proper cassettes. 
For the most accurate types of photogram- 
metry, plates are a necessary prerequisite. On 
the other hand, there are several drawbacks 
with plates. They are not easy to handle. 
They are heavy. They must be transported 
with great care. They are expensive. Only a 
limited number of emulsion types are avail- 
able. Delivery times are often long, and the 
shortest exposure interval is long. Several of 
these drawbacks are eliminated if roll film or 
cut sheet film is used, but then certain pre- 
cautions have to be taken to flatten the film 
before exposure, and to control the stability of 
the film during the photographic processes 
and storage. With the Verostat, P32, Nikon 
TS-20, and the Zeiss Jena SMK cut sheet film 
in special cassettes may be used. The Zeiss 
Jena UMK, Wild P32, Officine Galileo Tec- 
noster A, and Hasselblad MK70 cameras are 
the only cameras that can be equipped with 
roll film magazines. The flattening of the film 
is, in the UMK and Tecnoster, provided by 
suction plates, while the others rely on glass 
plate in the image plane. The film deforma- 
tions are controlled by four or five fiducial 
marks. The Hasselblad MK70 is the only 
camera having a reseau (25 points), which for 
digital data reduction yields an excellent 
means of image coordinate refinement. The 
roll film version of the UMK and the MK70 
have automatic film transport, and the short- 
est exposure intervals are 3 and 1 seconds 
respectively. This facility is very convenient 
for remote-controlled firing, and for the 
recording or documentation or measuring of 
slowly moving objects or events. 
The flatness of the plates is classified in 
three categories: standard, ultra flat (12.5 
prm/inch), and micro flat (0.5 um/inch). Ultra- 
flat plates cannot always be obtained from 
stock, (the Wild Company now stock such 
plates as a service to their customers). Micro- 
flat plates must be ordered in sufficiently 
large numbers before production and even 
then one cannot be sure of delivery, which is 
dependent on the manufacturer’s production 
schedules. The cost of such plates is very 
high and the use of them can only be advo- 
cated for projects where the utmost accuracy 
is required. 
NON-METRIC CAMERAS 
The use of non-metric cameras compared 
to metric cameras for photogrammetric pur- 
poses, has the following advantages and dis- 
advantages according to Karara!5. 
Advantages: 
* General availability,