Lens Types

There are many types lenses and every type has own features. According to function and structure difference, lens price shows a great range among them. For example, motorized zoom lens is 10 times as expensive as common mono-focal lens. So we must learn all kinds of lens characters in order to freely select lens.

A, Fixed aperture mono-focal lens

Fixed aperture mono focal lens is a kind of simple lens. This lens has a manual adjustment ring (labeled some distance numbers). Adjusting ring can make CCD image optimum, also make screen image optimum.

Due to fixed aperture, there is no ring in lens, i.e. aperture is nonadjustable. So we do not adjust lens to change luminous flux, and we have to change spot illumination to change flux, such as add or reduce lights. Such lens usually applies in constant illumination conditions, such as light shining indoor environments. At other environments it is needed to match with auto shutter camera (of course, current CCD cameras support auto electronic shutter), adjusting light flux by shutter.

B, Mono focal & Manual-iris lenses

Mono focal & manual-iris lens adds adjusting ring which fixed aperture lens does not have. Aperture adjusting ranges from F1.2, F1.4 to closed. It is easy to suit spot illumination. However, this type of aperture is adjusted manually, and when camera mount finishes, position is fixed. Readjusting aperture is not easy. Thus such lens is mainly used in constant illumination environments; at other environments it must matches with electronic shutter camera. Such as in early& late vs. midday, sunny day vs. cloudy day suchlike strong contrast conditions, it is necessary to adjust flux by shutter.

C, Mono focal & Auto-iris lens

Mono focal & auto-iris lens structure changes a lot, it equals adding a micro-motor with mesh transmission on adjusting ring of mono focal & manual-iris lens, driver circuit stretch out 3-core or 4-core line to auto-iris lens so as to make micro-motor positive or reverse rotate and control aperture size. Auto aperture lens can also be with-amplifier (video derive) or without-amplifier (DC drive).

D, Varifocal Manual Iris Lens

Just as the name implies, varifocal manual iris lens has changeable focal-length and adjusting ring which can adjust focal-length in certain range with 2~3X zoom and 3.6~8 mm focal-length. At practical applications, manual adjustment of ring can easily select spot angle, i.e.: whole space monitoring of room or partial monitoring is available. This kind of lens is very important when spot is unfamiliar.

For most CCTV projects, once camera has been fixed, it is inconvenient to manual zoom frequently. So varifocal manual iris lens is mainly used in strict conditions which is hard for mono focal lens to meet demand. However, such lens is welcomed by engineering people, for such lens can be adjusted until meet demand instead of replacing various lenses. This feature is much welcomed out of town project.

E, Auto Iris Motorized Zoom Lens

This kind of lens adds two more micro-motors than the above Mono focal & Auto-iris lens. The one is meshed to zoom ring of lens whose turning can change focus; the other one is meshed to focus ring which achieves focus. As such lens adds two functions of remote-control, the lens is also called two motorized zoom lens.

Auto Iris Motorized Zoom Lens usually stretches out two beams multi-core line. One controls auto iris. The method is same with the control line of Mono focal & Auto-iris lens. The other controls lens zoom and focus, which often connects with PTZ controller & decoder. When we remotely manage focus ring and zoom ring of indoor PTZ controller & decoder, focus or zoom control-lines will appear DC voltage (+/－). This voltage adds on related micro-motor, so as to ensure lens' zoom and focus adjustment.