Very useful APO lens, 280 ~ 800 mm

This APO lens ranges 280 - 800mm is very useful for nature and animal hotographers in particular, who use multiple focal lengths in this range and, with the LEICA APO-EXTENDER-R 2x even up to 1,600 mm. This can be used to replace a range of fixed focal length lenses. As a result, two lens heads and three focus modules instantly create six APO lenses, all providing consistent top-class optical quality from Leica.

Advantage Of USM Based Lens.

Most USM-equipped lenses allow full-time manual focus even in the AF mode. The ring USMs are suitable for large aperture lenses and super telephoto lenses, and the Micro USMs for smaller lenses.The amplitude width of the elastic stator is only around 0.001mm.

USM Technology from Canon.

The USM,Ultrasonic Motor, is a driving motor that Canon commercialized for the first time on camera lens in the world. Ultrasonic motors, are based on a different principle in which rotational force is producing from ultrasonic vibration energy. USM makes focusing very faster, high accurate and quieter than ordinary focusing drive motor and speed-reducing gear train.

USM construction is very very simple, consisting of an elastic stator and a rotating rotor. The stator with a piezoelectric ceramic type elements in that, while energized by an AC voltage, it vibrates and to generate ultrasonic vibration energy. That vibration energy is using to produce continuously rotate the rotor through the pressure contact between the rotor and stator.

Benefits of Inner and Rear focusing Lenses.

The rear and inner focusing systems have the following benefits.

1. Easy handling of the lens because of unchanged total length of the lens during focusing. 2. Easier to shorten the minimum shooting distance compared to the all-group focusing and front-group focusing methods. 3. Easier operation of the polarizing filters because of non-rotating front frame.

Lens Focusing Systems.

General photographic lenses carry out focusing using either the all-group focusing, in which all lens groups are moved together along the optical axis, or the front-group focusing, in which only front lens group is moved. Those focusing systems require much energy for focus driving mechanism, thereby preventing faster auto focusing. Such focusing systems are also difficult to make the lenses compact due to large front lens groups.

The rear and inner focusing systems are developed mainly to reduce the weight of moving focusing lens group. The rear and inner focusing systems employ, as a focusing lens group, optical systems other than the front lens group.

The terms such as "inner focusing" meaning lens group(s) between front lens and diaphragm controls focusing, and "rear focusing" meaning lens group(s) behind diaphragm controls focusing.

First Microcomputer Controlled SLR Camera

Canon AE-1 is the world's first camera with a mini microcomputer, introduced in 1976 with the features of automatic and electronic technologies with the 35mm SLR camera.

It is centrally controlled by a microcomputer.

Rangefinder System

When 35mm cameras marketed with rangefinder were the most popular, an advanced camera was Leica "M3", which was far superior to any other camera in the world. The rangefinder system captures the natural vitality of a situation.It helps to the photographer to frame his subject - a scene, a mood, a moment - through the rangefinder camera without losing view of what's happening outside the viewfinder frame.