Micro spy cameras are inexpensive and easy to install in covert locations
At one time, a decent low light video camera was the size of pop can and cost several hundred dollars. Now, you can purchase a decent micro spy camera that will fit into a marker lid for well under a hundred dollars. Tiny security cameras also offer a huge variety of lenses to allow for practically about any angle of view and covert installation. These cameras are also very easy to connect since they have used the same basic video standard since the invention of the television.
This introduction to security cameras will give you the required basic information needed to install and power up practically any type of security camera.
I use these small video cameras for security work, machine vision experiments and robotic projects. They range in size from half an inch square to a quite large depending on the features, imaging system, and type of lens installed. For most security installations, a small board camera with a fixed medium to wide angle lens will be perfect, but there are times when you need to see a much larger area or over great distances, so these cameras have several body types that allow the use of multiple lens styles.
Extremely tiny spy cameras will not have this option, as they use a very tiny glass or plastic lens built right into the housing. There will be a bit of a trade-off between image quality and size.
Figure 1 - A few of the basic security cameras in my ever growing collection
For most covert work, size will be the key factor in camera selection, so you probably won't be dealing with multiple lenses or even have a choice. In Figure 1, you can see the huge difference in size between the long range motorized lens telephoto camera on the left and the tiny spy camera at the front of the photo. The tiny spy camera has a simple fixed medium angle lens and will run from a 6 volt power source for many hours. The larger camera uses a computer to control the motorized zoom lens and requires multiple power sources and electronic control systems in order to operate.
Of course, the zoom lens can see the color of your eyes from 500 feet away, but the tiny spy cam can be hidden just about anywhere. There will always be a camera available to suit your needs as long as you have the budget to afford it.