Description
Tamron Lens 28-200MM AF 171D Aspheric
In 1996, the Model 171D was released. The 171D differed markedly from its predecessor, the Model 71D, in the minimum focus distance. The distance, which was 2.1 m for the Model 71D, was suddenly shortened to 52cm, although this was available only when the lens was used at a focal length of 135mm. The maximum magnification, or the maximum size of the object on the film, increased from approx. 0.11x to approx. 0.21x, making the 171D an even more user-friendly, all-in-one zoom lens.
This upgrade was enabled by use of an alternative focusing system. The system adopted for the Model 71D was the front focus system, in which the large lens in front was moved outward as the camera approached the object. The Model 171D alternatively applied the internal focus system, which permitted focus by moving the small lens within the barrel (the length of the lens barrel remained unchanged irrespective of the shooting distance). This enabled shooting from up close without sacrificing performance. This upgrade was welcomed by camera aficionados. However, the development team was still not completely satisfied with this model, because its minimum focus distance fluctuated somewhat depending on the focal length.
max. aperture: 3.8-5.6
min. aperture: 22
aperture note: 3.8-5.6
focal range(mm): 28-200
elements/group: 16/14
aperture blades: 6
angle of view: 75° – 12°
