The infrared zoom lens is a camera lens that can change the focal length within a specific range to obtain different wide and narrow angles of view, images of various sizes, and various scene ranges.
The infrared zoom lens can change the shooting range by changing the focal length without changing the shooting distance. Therefore, the infrared zoom lens is very conducive to picture composition.
Since one infrared zoom lens can serve as several fixed-focus lenses, it reduces the number of photographic equipment carried when travelling and saves time for lens replacement.
The infrared zoom lens is divided into electric infrared zoom lenses, manual focusing IR lenses.
1. price is high;
2. The size is large;
3. Its imaging is often not as clear as a good fixed focal lens under any certain focal length.
Leaving aside the inherent defects of infrared zoom lenses, the optical industry uses computers to design many perfect zoom lenses.
The imaging of many zoom lenses is already apparent, and the size is already relatively small, but the price is still very high.
Infrared zoom lenses are more prone to halo than other lenses, so a suitable hood is indispensable.
Sometimes the occlusion caused by the lens hood is not visible on the viewfinder screen of a single-lens reflex camera, but it can be displayed on the film. This situation is most obvious when shooting with a small aperture. Infrared zoom lenses often use a hood.
Some lens hoods are effective at the long focal length end, but when zooming to the short focal length end, the photo will produce vignetting caused by occlusion that cannot be seen on the viewfinder screen.
Some infrared zoom lenses need to turn two separate control rings, one to control focusing and the other to control the focus length. The advantage of this structural layout is that once the focus is completed, the focus point will not be accidentally changed by adjusting the focal length.
Other tyoes of the SWIR zoom lens only need to move a control ring, turn it to focus, and slide it back and forth to change the focal length.
This "single ring" zoom lens is often faster and more convenient for operation, but it is usually more expensive. It should be noted that when changing the focal length, do not lose the clear focus of the infrared zoom lens.
Use the support appropriately. When using a focal length of 300NM or longer, the lens should be fixed on a support such as a tripod to ensure the stability during shooting.