Choosing the right lens for your meteor camera can drastically increase performance.
To get the best out of your camera you will need a good quality lens. Apart from the overall quality of the image your choice of lens will determine the limiting magnitude of your camera, i.e. the camera's ability to detect faint meteors as well as the camera's field of view.
An “auto iris” lens is required to protect the CCTV sensor from direct sunlight. The camera will be outside day and night and direct sunlight could burn the CCD sensor. A simple domestic timer protects the camera sensor from damage during daylight hours by switching off the power and causing the iris to close. An alternative to a timer is to use a daylight sensor to switch off the power supply in the daytime. This is discussed in more detail in the section on power supplies.
Lenses attach to the camera via a screw fitting which enables a range of lenses to be used. The Watec camera has a “CS” lens mounting system in which the lens screws onto a one-inch flange on the end of the camera. The “CS” mount on the Watec is 5mm shorter than the standard “C” mounting system used by most CCTV cameras. This allows the Watec to use a wider range of lenses.
Your lens choice may depend on your choice of camera but any good quality varifocal (zoom) lens of around F1.2 with focal length in the range 3mm to 12mm lens will provide good limiting magnitude. A lens such as this will enable the camera to operate with a field of view from anywhere between 35 degrees to well over 80 degrees but operating beyond 70 degrees is not ideal. Fainter meteors will not be detected and optical aberration becomes very significant.
Example combinations of KDM-6101G camera and Computar TG3Z2910FCS lens:
To get the best out of your expensive Watec camera, you’ll need a good auto-iris lens. Quality lenses that are a good match for the Watec are:
Note that the Watec has a “CS” lens mounting system, which means that the lens screws onto a one-inch-wide flange on the end of the camera. The “CS” mount on the Watec is 5mm shorter than the standard “C” setting for CCTV cameras, which means that a wider range of lenses can be used.
The “Computar HG3Z4512FCS-IR” lens is suitable for a “CS” fitting, so no adaptor is needed. The “Tamron GL412IRDD” is designed for the longer “C” flange, so if used will need an adaptor to extend the CS fitting by 5mm. These adaptors are widely available and cost £3 to £5.