Which cameras?
On the cradles for aerial photography, there can be installed:
the film cameras,
the digital cameras,
the camcorders.
The film cameras have a quality/cost ratio still unequalled.
The digital cameras are inexorably increasing photographic definition and reproduction of colors. To get the image quality of a film camera, the it must be turned on the top models, with expensive prices. On the other hand, some cheap digital cameras with fix lens gives the opportunity to start kaping at minimum cost with some other interesting advantages.
A camcorder needs ideal flight conditions, and a cradle with perfect stabilization. Its use is thus rather not frequent.
  Compare the lenses by their focal length is rather impossible as there are now so many different sizes.
The most practical way is to use the angular field.


How to choose?
For each category of camera I have indicated the applicable criteria for a kap use. Moreover, hereafter are the principles to which I'm personally keen:
The electric shutter release
Practically, no camera have a plug for electric shutter release. One must be installed. The advantage of this system is first its great reliability, and, second, the possibility to install easily different cameras on the same cradle, without to be obliged to make consistent modifications.
The image quality
When a photograph is successfully done, I wish to enlarge it to a 30x40cm at least. Besides, the reproduction of colors, the clearness of shadows, the accuracy of details, the lack of vignetting effect are necessary for me.
The shutter release delay
In kap practice, as in sport photography, it is peremptory to catch the instant, and a camera which let spend some valuable fractions of seconds before to fire is not suitable.

Focus lock

Lock the focus is an important con'. However, be suspicious on cameras which do not set the lens in position before but only memorize it, and then action the lens motor when released, thus loosing valuable fractions of seconds! As example, the Leica Minilux.



Some cheap digital cameras with fix lens have a sufficient quality to start with. It is rather easy to install an electric shutter release. The digital camera let verify immediately after the shot if the orientation is correct. Then,  a good film camera will let shot good quality pictures with a modest investment .