Sony ALCSH0006 Aspherical lens elements ED and Super ED glass, Rear focusing mechanism, STF lens

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A lens technology

The technology required to produce first-class interchangeable camera lenses is very sophisticated indeed, and that applies to every phase of the production process from design through precision parts manufacturing and assembly to stringent quality assurance testing and more. Sony brings a distinguished history of excellence in all of these areas to bear in producing the A lenses. You’ll feel the difference in the way A lenses handle, and you’ll see the difference in the superior image quality they deliver.

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 (Extra-low Dispersion)

 

 

 

 

problem in large-aperture lenses.The most

 

 

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 plane.Well-designed aspherical lens can reduce the number of elements in the lens for less overall size and weight.

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 direct-drive piezoelectric motor that is capable of delivering high torque even at low speeds, with almost instantaneous start/ stop response. Its fast response and low-noise operation translate directly into quick, quiet autofocus operation. SSM lenses also include position detection for enhanced focusing precision. Other advantages of this advanced drive system are that the focus ring does not rotate during autofocus operation, and you can directly switch to manual focusing by simply rotating the focus ring.

 

 

 

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 in-focus areas. STF technology employs a special “apodization” element that causes the intensity of defocused point light sources to fade out radially so that no sharply defined edges or geometry remain.The result is extraordinarily creamy defocusing that goes beyond the capabilities of conventional lens technology.

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 flat-sided polygon when the lens is stepped down, the number of sides corresponding to the number of blades in the aperture.This results in the familiar polygonal out-of-focus highlights seen in many photographs. Almost all A lenses feature a unique circular aperture that contributes to smooth, natural defocusing.

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”)

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Contents Lenses Creation Contents Elements and groups If a little hole can do all of this, why do we need lenses?Zoom and focus mechanisms Refraction bending lightSony A-mount and E-mount systems Three keys to effective defocusingAperture and exposure Number mathFocal length Other macro lens characteristics you should know aboutMaximum magnification ratio Technical definition of focal lengthScientific approach Use your lens hoodNeutral density filters Scene to come throughPortraits Resolution, contrast and sharpnessMacro and close-ups LandscapesAspherical lens elements ED and Super ED glass Rear focusing mechanismAuto clutch Floating lens mechanism SSM Super Sonic wave MotorDT 11-18mm F4.5-5.6 SAL1118 Zoom LensesDT 16-50mm F2.8 SSM SAL1650 Weight approx 470 gDT 18-200mm F3.5-6.3 SAL18200 DT 18-55mm F3.5-5.6 SAM SAL1855DT 18-250mm F3.5-6.3 SAL18250 28-75mm F2.8 SAM SAL287528mm to 300mm 75-300mm F4.5-5.6 SAL75300 DT 55-200mm F4-5.6 SAM SAL55200-2Providing outstanding image quality from 18mm to 200mm High-performance full-frame bodies16mm F2.8 Fisheye SAL16F28 Fixed Focal Length Lenses20mm F2.8 SAL20F28 28mm F2.8 SAL28F28 50mm F1.4 SAL50F14 DT 35mm F1.8 SAM SAL35F1885mm F2.8 SAM SAL85F28 DT 50mm F1.8 SAM SAL50F18DT 30mm F2.8 Macro SAM SAL30M28 135mm F2.8 T4.5 STF SAL135F28100mm F2.8 Macro SAL100M28 50mm F2.8 Macro SAL50M2870-200mm F2.8 G SAL70200G Lenses70-400mm F4-5.6 G SSM SAL70400G 70-300mm F4.5-5.6 G SSM SAL70300G300mm F2.8 G SAL300F28G 35mm F1.4 G SAL35F14G0x Teleconverter 4x TeleconverterVario-Sonnar T* DT 16-80mm F3.5-4.5 ZA SAL1680Z Vario-Sonnar T* 16-35mm F2.8 ZA SSM SAL1635ZDistagon T* 24mm F2 ZA SSM SAL24F20Z Vario-Sonnar T* 24-70mm F2.8 ZA SSM SAL2470ZSonnar T* 135mm F1.8 ZA SAL135F18Z Planar T* 85mm F1.4 ZA SAL85F14ZMount Lenses 16mm F2.8  SEL16F28Fisheye Converter Ultra Wide Converter 18-55mm F3.5-5.6 OSS SEL1855 Sonnar T* E 24mm F1.8 ZA SEL24F18Z18-200mm F3.5-6.3 OSS SEL18200 55-210mm F 4.5-6.3 OSS SEL55210Unwanted camera noise 30mm F3.5 Macro SEL30M35 50mm F1.8 OSS SEL50F18Main specifications of a lenses Lens accessories DI11012