A lens technology
The technology required to produce
Internal focusing mechanism |
|
| SAM (Smooth Autofocus Motor) |
|
|
|
| ||
|
|
|
|
|
In this type of lens, focusing is achieved by moving only the internal elements. |
| SAM is another type of internal lens motor for autofocus drive. While the SSM | ||
The overall length of the lens remains constant, and the filter mounting |
| motor described above is piezoelectric, the SAM motor is electromagnetic in | ||
thread at the front of the lens remains stationary during focusing.The latter |
| operation, but provides similar benefits: responsive autofocus operation that | ||
characteristic is an advantage when using a polarizing filter. Other advantages |
| does not require mechanical coupling from the camera body. | ||
include fast autofocus response and reduced minimum focusing distances. |
|
|
|
Aspherical lens elements |
|
| ED and Super ED glass |
|
|
| ||
|
|
|
| |||||
|
|
|
|
|
|
|
| |
Spherical aberration, slight misalignment at |
|
| Chromatic aberration in conventional |
|
|
|
| |
|
|
|
|
|
| |||
the image plane between light that has passed |
|
| optical glass elements can reduce contrast, |
|
|
|
| |
through the center and periphery of a simple |
|
| resolution, and color fidelity, particularly at |
|
|
|
| |
spherical lens, can become a noticeable |
|
| longer focal lengths. ED |
|
|
|
| |
problem in |
|
| and Super ED glass were developed with |
|
|
|
| |
effective solution is to use one or more specially |
|
| refractive index and dispersion characteristics |
|
|
|
| |
shaped aspherical elements near the aperture |
|
| specially tailored to counter this problem. |
|
|
|
| |
stop to restore perfect alignment at the image |
|
| Lenses that include ED or Super ED glass |
|
|
|
| |
plane, thus maintaining high contrast even |
|
| elements provide superior contrast and |
|
|
|
| |
with the aperture wide open.Aspherical lenses |
|
| resolution throughout the image even at |
|
|
|
| |
|
|
|
|
|
| |||
arranged far from the aperture stop can minimize image distortion and flatness |
| large aperture settings. |
of the image
Spherical lens | Aspherical lens |
| Conventional glass | ED glass | Super ED glass | ||||||||
|
|
|
|
|
|
|
|
|
|
|
|
| |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Image |
|
| Image |
|
|
|
|
|
|
| ||
| sensor |
|
| sensor |
|
|
|
|
|
|
| ||
| plane |
|
| plane |
|
|
|
|
|
|
| ||
|
|
| Image sensor | Image sensor | Image sensor | ||||||||
|
|
|
|
|
|
|
| ||||||
|
|
|
|
|
|
|
| plane | plane | plane | |||
Auto clutch |
|
|
|
|
| Floating lens mechanism |
|
| |||||
|
|
|
|
|
|
| |||||||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
The auto clutch mechanism decouples the focus ring so that it does not |
| This focusing feature is particularly important in certain lenses that are | |||||||||||
rotate during autofocus operation.This allows the lens to be cradled in one |
| designed for close focusing. It maintains optimum lens performance and | |||||||||||
hand without interfering with autofocus operation, for improved shooting |
| therefore maximum sharpness right down to the minimum focusing distance | |||||||||||
comfort and versatility. |
|
|
|
|
| by moving “floating” elements independently when focusing, rather than | |||||||
|
|
|
|
|
|
|
| moving the entire optical assembly as a whole. |
|
|
Rear focusing mechanism
This focusing configuration has similar advantages to internal focusing, described above, but focusing is achieved by moving the rear lens elements rather than the internal elements.
SSM (Super Sonic wave Motor)
SSM is an advanced
|
|
| Piezoelectric |
|
| AC voltage, | element |
|
| Stator | |
|
| Phase B | |
|
| Rotor | |
|
| AC voltage, | |
|
|
| |
Rotor | Stator | Phase A |
|
|
|
STF lens
A unique A lens feature currently available only in the SAL135F28, STF
(Smooth Trans Focus) is an optical technology that is aimed specifically at creating the smoothest, most visually pleasing defocusing effect possible while retaining full resolution and contrast at
STF lens
Apodization optical element
A | a |
|
b c
Defocusing of STF lens
(around focus point “a”)
Conventional lens
A | a |
|
Circular aperture
Standard lens apertures appear as a
Comparison of aperture design
Conventional aperture | Circular aperture |
Focus hold button
Press this button to lock focus at the current setting.The focus hold button is on the lens barrel right under your fingertip for convenient, fast operation.
Focus range limiter
This feature can be used to limit focus range when you need the quickest possible autofocus response. On some lenses a single “limit” range will match the characteristics of the lens (near focus limit on macro lenses, for example), while some lenses have a “near/far” limit range switch.
SSM consists of a rotor (left), and a stator (right) on which plexoelectric elements are mounted.
b c
Defocusing of conventional lens (around focus point “a”)
16
17