Sony FE 400mm F/2.8 GM OSS (SEL400F28GM)

Super telephoto prime lens • Digital era

FE The lens is designed both for Sony full frame and APS-C digital mirrorless cameras.
GM Professional lens with high quality optics and robust build. Meets the highest standards and provides excellent performance and flawless image quality unachievable with traditional optical technologies.
OSS The lens is equipped with Optical SteadyShot.

Specification

Announced: June 2018
Production status: In production
Maximum format: 35mm full frame
Mount: Sony E
Optical design
Diagonal angle of view: 6.2° (35mm full frame)
(Sony APS-C)
Lens construction: 23 elements in 17 groups, including 3 FL, 1 ED
Diaphragm mechanism
Number of blades: 11
Focusing
Focusing method: Internal focusing (IF)
Closest focusing distance: 2.7m
Focusing distance range limiter: FULL;2.7-7;7-
Focusing modes: Both autofocus and manual focus
Type of autofocus motor: Dual XD Linear Motor
Focus mode selector: AF/MF
Direct Manual Focus (DMF): Determined by camera
Additional features: AF Stop Button
Image stabilizer
Optical SteadyShot (OSS): Yes
Stabilizer features: Mode 1
Mode 2
Mode 3
Stabilizer efficiency: No information
Physical characteristics
Weight: 2895g
Maximum diameter x Length: Ø158.1×359mm
Materials: Metallic barrel, metallic mount
Weather sealing: Dust-proof and water-resistant barrel
Fluorine coating: Front element
Filters: 40.5mm (rear)
Lens hood: Slip-on ALC-SH155 (round, plastic)

Manufacturer descriptions

Sony Introduces the Long-Awaited 400mm F2.8 G Master™ Prime Lens

Sony Electronics - 06/27/2018

SAN DIEGO, June 27, 2018 /PRNewswire/ -- Sony – a worldwide leader in digital imaging and the world's largest image sensor manufacturer – has today announced the highly anticipated FE 400mm F2.8 GM OSS large aperture super-telephoto prime lens (model SEL400F28GM).

The product of extensive research and testing, Sony's new FE 400mm F2.8 GM OSS lens is the first large aperture super-telephoto prime to join the E-mount lineup. This exciting new lens produces brilliant image quality with extraordinary focusing speed and precision, while also boasting the lightest weight in its classi and an extremely balanced design. It's the ideal choice for professional sports, wildlife and nature photographers, and a perfect complement to Sony's extensive lineup of high-speed E-mount bodies including α9, α7R III and more.

"We're extremely excited and proud to officially introduce the new 400mm F2.8 G Master prime lens," said Neal Manowitz, Vice President of digital imaging at Sony Electronics. "The latest in our flagship series of G Master Lenses, this new lens offers exceptional image quality and an innovative lightweight design that will give professionals a level of flexibility with a 400mm lens unlike anything they've ever experienced. Combined with the unmatched shooting speeds and autofocus capabilities of our full-frame E-mount cameras, it will allow them to capture and create in ways that were never before possible."

World's Lightest 400mm F2.8 Prime with Ideal Balance for Monopod or Handheld Shooting Weighing it at only slightly more than 6 lbs., the new FE 400mm F2.8 GM OSS lens provides a level of portability and handheld maneuverability that has never before been achieved in a lens of its class. The remarkably light weight of this lens is achieved through an innovative optical design that includes three fluorite elements, with a reduced number of elements deployed at the front of the barrel, as well as the liberal usage of durable magnesium alloy components.

Repeated field tests and evaluation by professional photographers across the world have led to a lens design that is not front-heavy, reducing moment of inertia that resists rotation by up to 50% as compared to the SAL500F40Gii, ensuring quicker, more precise panning when shooting handheld or on a monopod.

To best take advantage of the rapidly evolving shooting and focusing speeds of Sony's latest cameras, the FE 400mm F2.8 GM OSS lens features two newly developed high-speed XD (extreme dynamic) Linear Motors that drive the lens's focus group, achieving up to a 5x improvementiii in moving-subject tracking performance. These motors are supported by specially developed motion algorithms to minimize lag and instability, and control noise levels, resulting in exceptionally quick, accurate and quiet autofocus performance. This allows the lens to capture dynamic, fast moving athletes or wildlife with ease.

A member of Sony's flagship G Master series lenses, this new large aperture super-telephoto prime lens features an incredible level of image quality and detail, with outstanding contrast and resolution maintained all the way to the corners of the image. The unique optical design includes three fluorite elements that help to minimize chromatic aberration and suppress any amount of color bleeding. The lens has also been coated with Sony's original Nano AR coating to suppress any unwanted reflections, glare, or ghosting.

In addition to the impressive resolution, the lens features an 11-blade circular aperture mechanism that allows it to produce extremely natural and beautiful background defocus or 'bokeh'.

The new FE 400mm F2.8 GM OSS is compatible with Sony's 1.4x and 2.0x E-mount tele-converters, producing outstanding imaging performance at extended focal lengthsiv while maintaining fast, precise AF performance.

To withstand the harsh conditions of sporting events and wildlife photography, Sony's new FE 400mm F2.8 GM OSS is built with a durable magnesium alloy and a strong, lightweight carbon fiber hood. The lens is also dust and moisture resistantv, and its front element is coated with fluorine to resist dirt and fingerprints.

There is also an ample number of hard controls on the lens, including customizable focus-hold buttons in four different locations on the lens barrel, which can be programmed for control of features such as Eye AF functionality, if desired. There is also a 'Full-Time DMF' switch to immediately engage manual focus at any point, and a focus ring that features Linear Response MF for fine, responsive manual focus. Additionally, the new lens includes built-in optical stabilization for dynamic action and three different 'Mode' settings, including a brand new Mode 3vi setting with an advanced algorithm that ensures easier framing when following moving subjects. It also features a function ring with selectable 'Preset' and 'Functionvii' settings, which is a first for any Sony lens.

The FE 400mm F2.8 GM OSS includes a drop-in filter slotviii that accepts ø 40.5mm ND and other filter types, as well as the optional VF-DCPL1 Drop-in Circular Polarizing Filter. The VF-DCPL1 filter can be rotated to achieve the desired polarization while installed in the lens.


Sony's most advanced lens technologies have been unsparingly applied in this large-aperture super telephoto lens, achieving extraordinary speed, outstanding G Master resolution and bokeh, plus professional control and reliability. Moreover, the SEL400F28GM is a remarkably lightweight super telephoto lens, providing unparalleled handheld shooting freedom.

The XD Linear Motors used in the SEL400F28GM have been newly developed to deliver higher thrust and efficiency than conventional types in order to make the most of the rapidly evolving speed performance of current and future camera bodies. The linear motor design and component layout have been thoroughly revised to achieve significantly higher thrust. Two of these new motors are used in the SEL400F28GM, achieving up to a 5x improvement2 in moving-subject tracking performance. This means that the full speed performance of advanced camera bodies can be applied to capturing perfect images of the most dynamic sports or wildlife subjects. The XD motors are further supported by new algorithms developed specifically for them, notably improving the motors' response to control signals and minimizing lag and instability that can occur when driving a large aperture focus lens group for quiet, low-vibration operation.

All lenses bearing the G Master brand are designed to extremely high standards, ensuring that outstanding contrast at high spatial frequencies is maintained right out to the image edges. The optical design includes three fluorite elements that help to minimize axial chromatic aberration that can be a problem in large-aperture lenses, as well as lateral chromatic aberration that can reduce resolution towards the image periphery. Color bleeding is effectively suppressed, allowing clear reproduction of the finest subject details.

In addition to careful control of spherical aberration at the design stage, each lens is individually tested and adjusted during manufacture to achieve the highest possible bokeh quality. An 11-blade circular aperture mechanism further contributes to smooth circular bokeh. The SEL400F28GM allows the narrow depth of field achievable with a 400 mm F2.8 lens to be utilized to create images with deep, lush, defocused backgrounds.

Optional high-performance 1.4x and 2.0x tele-converters are supported, providing up to 800 mm focal length (1200 mm equivalent on APS-C bodies) with an F5.6 maximum aperture3. Outstanding imaging performance and fast, precise AF operation are maintained when either of these excellent tele-converters are used, ensuring that the lens's superior G Master image quality is not compromised.

An innovative optical design that includes three fluorite elements and reduces the number of elements deployed at the front of the lens barrel is behind the remarkably light weight of this fine lens. Another weight-reducing factor is the use of durable magnesium alloy components in the barrel. The SEL400F28GM weighs just 102.2 oz (2,895 g), providing portability and handheld maneuverability that active photographers will appreciate. Repeated field tests and evaluation by professional photographers has led to a design that is not front-heavy, reducing moment of inertia that resists rotation by up to approx. 50% compared to the SAL500F40G.4 Quicker, more precise panning is assured whether shooting handheld or on a monopod.

A durable magnesium alloy is used not only for the lens barrel exterior and tripod mount, but also for interior barrel components as well. This provides the tough durability that demanding professional applications require, while minimizing overall weight.

The dust- and moisture-resistant design provides the reliability needed for outdoor use in harsh conditions.

The number of mount attachment screws has been increased to ensure maximum rigidity and durability that will easily withstand professional use.

The supplied lens hood is made of strong, lightweight carbon fiber, with interior flocking for optimum light control.

The front lens element features a fluorine coating that helps to prevent dirt and fingerprints from sticking, while making it easier to wipe dirt and fingerprints away if they do become attached to the lens surface.

Optical image stabilization is built in, making it easier to capture sharp images when shooting handheld. In addition to the Mode 2 setting that is provided for panning shots, the SEL400F28GM features a new Mode 36 setting with an advanced algorithm that ensures easier framing when following moving subjects. Mode 36 provides optimum stabilization for tracking and shooting dynamic, unpredictable sports action. 5-axis image stabilization becomes available when the SEL400F28GM is used with an α body that features in-body image stabilization.

When the FULL TIME DMF switch is ON, manual focus is immediately engaged by simply rotating the focus ring, even while shooting in the AF-C mode. If AF causes focus to shift to a different subject while shooting, the focus ring can be used to quickly bring focus back to the desired subject. In situations where the user wants to fine-tune focus manually after initial AF, the body's shutter button half-press focus function can be turned off and AF assigned to a different button, making it easy to use the focus ring for final focus after initial AF has been achieved. The ability to instantly switch to manual focus can also be useful when it is necessary to focus beyond a set focus range limit.

A dedicated trunk style hard case is supplied to protect the lens from shock and vibration during transport.

The focus ring features Linear Response MF for fine, responsive manual focus control. Focus changes linearly in response to focus ring rotation, giving you the control immediacy needed for fast, accurate manual focusing.

The SEL400F28GM includes a new function ring with switch selectable PRESET (preset focus) and FUNCTION settings. Functions such as Power Focus can be assigned to the FUNCTION mode via a camera body menu.

Focus hold buttons are provided in four locations on the lens barrel for easy access in any shooting situation. The focus hold buttons can be customized via a camera body menu, allowing them to be assigned a function selected by the user: Eye AF, for example.

When the function ring select switch is set to FUNCTION and the function ring is rotated, focus shifts smoothly at a speed determined by the amount of function ring rotation. This allows smooth focus shift for movies.

When the function ring select switch is set to FUNCTION, the function ring can be rotated to switch between APS-C and full-frame angles of view.

The SET button is initially used to memorize the desired focus point. If the mode switch is then set to the PRESET position, moving the function ring in either direction will immediately set focus to the memorized point. This can be a huge advantage for sports and other rapidly changing situations, allowing focus to be preset in advance and instantly recalled to ensure that the decisive moment is properly captured. This function is available whether shooting with AF or MF, and can focus outside a set focus limit range.

The SEL400F28GM includes a filter slot that accepts ø 40.5 mm ND and other filter types, as well as the optional VF-DCPL1 drop-in circular polarizer. The VF-DCPL1 circular polarizer can be rotated to achieve the desired polarization while installed in the lens.

The tripod collar ring employs bearings to ensure smooth rotation as well as high reliability. The tripod collar ring also features 90-degree click stops and a switch that engages or disengages the click stops as required. With the click stops engaged it is easy to shift quickly between horizontal and vertical camera orientations. The click stops can be disengaged when smooth, low-resistance operation is desired.

The focus range limit switch allows a limited focus range to be selected when the fastest possible focusing is required. Three settings are provided: FULL, 7 m–2.7 m, and ∞–7 m.

Design and features

A member of Sony's G Master professional series of lenses designed with emphasis on high resolution and high quality bokeh. The first large aperture super-telephoto prime lens in the E-mount lineup.

The lens barrel is large, heavy, made of metal. The lens mount is metallic and features a rubber gasket to prevent water from entering the camera chamber throughout the lens mount. The lens has a dust-proof and water-resistant construction for keeping it in working condition even in extreme weather conditions (snowfall, rain, fog etc.). The weight of the lens is redistributed to the back, making tracking subjects and panning easier.

The focusing ring is not physically coupled with the focusing mechanism and works electronically (focus-by-wire): turning of the ring actuates an electric motor that moves the focusing group of the lens to the proper position to achieve sharp focus.

The focusing ring features Linear Response MF for fine, responsive manual focus.

The lens features AF/MF focus mode switch.

AFAutofocus mode.
MFManual focus mode.

During autofocus operation, you can press the AF Stop button of the lens to temporarily pause autofocus. This lets you stop autofocus whenever any unwanted obstacle comes closer to the camera than the moving subject you are tracking. If the shutter button is still pressed halfway when the AF Stop button is released, autofocusing will continue as before. The AF Stop function also works in continuous autofocus mode. You can change the functions of the AF Stop button using the camera's custom functions menu.

The lens features focusing distance range limiter which allows to choose between the following focusing distance ranges:

FULLFull range of focusing distances.
2.7m - 7mRange of focusing distances suitable for shooting nearby subjects.
7m - ∞Range of focusing distances suitable for shooting distant subjects.

By setting the suitable focusing distance range, the actual autofocusing time can be shorter.

The lens includes a new function ring with switch selectable PRESET and FUNCTION settings. When the switch is set to the PRESET position, moving the function ring in either direction will immediately set focus to the memorized point. This can be a huge advantage for sports and other rapidly changing situations. This function is available whether shooting with AF or MF, and can focus outside a set focus limit range. To memorize the desired focus point, use the SET button. When the switch is set to the FUNCTION position and the function ring is rotated, focus shifts smoothly at a speed determined by the amount of function ring rotation, which is especially useful for recording movies.

A drop-in filter holder with a neutral filter comes with the lens. The holder accepts 40.5mm filters. The filter holder must be always in place because the filter is a part of the lens optical system.

A fluorine coating has been applied to the outer surface of the front lens element to repel particles of dust, water or oil drops for easier cleaning of the lens surface.

The round slip-on lens hood ALC-SH155 attaches to the lens barrel behind the front rim. A knurled screw tightens a retaining ring, holding the hood firmly to the lens. The rigid construction and secure fit provide maximum physical protection to the front lens element.

The lens' autofocus is driven by a Dual XD Linear Motor, which quickly and quietly tracks subjects even while shooting at high speeds.

The lens stabilization system can also be combined with select camera's sensor-shift type image stabilization for more effective control of camera blur.

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  1. Put camera on a tripod
  2. Disable image stabilization function
  3. Switch camera to aperture-priority automatic exposure mode (A/Av)
  4. Select at least aperture value F/8 to obtain as large depth of field as possible
  5. Use as low ISO as possible (f.e. 100 or 200) to achieve the widest dynamic range of sensor
  6. Use remote shutter control or self-timer (to set a delay before the shutter's firing) to avoid image blur due to camera shake at relatively slow shutter speeds
  1. Put camera on a monopod
  2. Disable image stabilization function
  3. Set image quality to JPEG
  4. Switch camera to shutter-priority automatic exposure mode (S/Tv)
  5. Set shutter speed to 1/500 - 1/1000 sec to "freeze" action in the frame
  6. Set the highest possible ISO at which your camera provides acceptable signal to noise ratio
  7. Do not use flash
  8. Shoot both in continuous AF and burst modes

Aperture

The aperture stop is an important element in most optical designs. Its most obvious feature is that it limits the amount of light that can reach the image/film plane. Typically, a fast shutter will require a larger aperture to ensure sufficient light exposure, and a slow shutter will require a smaller aperture to avoid excessive exposure.

A device called a diaphragm usually serves as the aperture stop, and controls the aperture. The diaphragm functions much like the iris of the eye – it controls the effective diameter of the lens opening. Reducing the aperture size increases the depth of field, which describes the extent to which subject matter lying closer than or farther from the actual plane of focus appears to be in focus. In general, the smaller the aperture (the larger the number), the greater the distance from the plane of focus the subject matter may be while still appearing in focus.

The lens aperture is usually specified as an f-number, the ratio of focal length to effective aperture diameter. A lens typically has a set of marked "f-stops" that the f-number can be set to. A lower f-number denotes a greater aperture opening which allows more light to reach the film or image sensor.

The specifications for a given lens typically include the maximum and minimum aperture sizes, for example, f/1.4–f/22. In this case f/1.4 is the maximum aperture (the widest opening), and f/22 is the minimum aperture (the smallest opening). The maximum aperture opening tends to be of most interest, and is always included when describing a lens. This value is also known as the lens "speed", as it affects the exposure time. Lenses with apertures opening f/2.8 or wider are referred to as "fast" lenses. Zoom lenses typically have a maximum relative aperture (minimum f-number) of f/2.8 to f/6.3 through their range. High-end lenses will have a constant aperture, such as f/2.8 or f/4, which means that the relative aperture will stay the same throughout the zoom range. A more typical consumer zoom will have a variable maximum relative aperture, since it is harder and more expensive to keep the maximum relative aperture proportional to focal length at long focal lengths; f/3.5 to f/5.6 is an example of a common variable aperture range in a consumer zoom lens.

Autofocus motor

Micromotors and built-in motors of Nikon, Pentax and Sony digital SLR cameras provide moderately noisy and acceptably fast autofocus.

With ultrasonic, linear or stepping motor it is possible to achieve very fast and virtually silent autofocus. Moreover, the use of linear or stepping motor ensures smooth continuous focusing which makes lenses with such types of motors ideal for video recording.

The accuracy of autofocus does not depend on type of used autofocus motor but depends on focusing method (contrast or phase detection), autofocus algorithms, lighting conditions and other factors.

Manual focus override in autofocus mode

Allows to perform final focusing manually after the camera has locked the focus automatically. Note that you don't have to switch camera and/or lens to manual focus mode.

Manual focus override in autofocus mode

Allows to perform final focusing manually after the camera has locked the focus automatically. Note that you don't have to switch camera and/or lens to manual focus mode.

Electronic manual focus override is performed in the following way: half-press the shutter button, wait until the camera has finished the autofocusing and then focus manually without releasing the shutter button using the focusing ring.

Image stabilizer

A technology used for reducing or even eliminating the effects of camera shake. Gyro sensors inside the lens detect camera shake and pass the data to a microcomputer. Then an image stabilization group of elements controlled by the microcomputer moves inside the lens and compensates camera shake in order to keep the image static on the imaging sensor or film. The technology allows to increase the shutter speed by several stops and shoot handheld in such lighting conditions and at such focal lengths where without image stabilizer you have to use tripod, decrease the shutter speed and/or increase the ISO setting which can lead to blurry and noisy images.

Focusing method

Photographic lenses carry out focusing using one of the following five methods:

Methods of internal and rear focusing have the following advantages:

Aspherical elements (ASPH, XA, XGM) are used in wide-angle lenses for correction of distortion and in large-aperture lenses for correction of spherical aberration, astigmatism and coma, thus ensuring excellent sharpness and contrast even at fully open aperture. The effect of the aspherical element is determined by its position within the optical formula: the more the aspherical element moves away from the aperture stop, the more it influences distortion; close to the aperture stop it can be particularly used to correct spherical aberration. Aspherical element can substitute one or several regular spherical elements to achieve similar or better optical results, which allows to develop more compact and lightweight lenses.

Low dispersion elements (AD, ED, LD, HLD, SD, UD etc) and fluorite elements minimize chromatic aberrations and ensure excellent sharpness and contrast even at fully open aperture.

Organic Blue Spectrum Refractive Optics (BR Optics) material placed between convex and concave elements made from traditional optical glass provides more efficient correction of lateral chromatic aberrations in comparison with fluorite, UD and even Super UD elements.

Diffraction elements (DO, PF) cancel chromatic aberrations at various wavelengths. This technology results in smaller and lighter lenses in comparison with traditional designs with no compromise in image quality.

High refractive index elements (XR, UXR, HID, HR, HRI etc) minimize field curvature and spherical aberration. High refractive index element can substitute one or several regular elements to achieve similar or better optical results, which allows to develop more compact and lightweight lenses.

Apodization element (APD) is in fact a radial gradient filter. It practically does not change the characteristics of light beam passing through its central part but absorbs the light at the periphery. It sort of softens the edges of the aperture making the transition from foreground to background zone very smooth and results in very attractive, natural looking and silky smooth bokeh.

Lens construction

Lens construction – a specific arrangement of elements and groups that make up the optical design, including type and size of elements, type of used materials etc.

Element - an individual piece of glass which makes up one component of a photographic lens. Photographic lenses are nearly always built up of multiple such elements.

Group – a cemented together pieces of glass which form a single unit or an individual piece of glass. The advantage is that there is no glass-air surfaces between cemented together pieces of glass, which reduces reflections.

Efficiency of Image Stabilizer

The efficiency of image stabilizer is measured in stops and each stop corresponds to a two-times increase of shutter speed. For example, if you are shooting at focal length of 80mm and it is known that the efficiency of image stabilizer is 3 stops, it means that during handheld shooting at such focal length you can use shutter speed of 1/10 second which is exactly 23 times longer than the shutter speed 1/80 second needed to obtain sharp image in sufficient lighting conditions.

Zooming method

The rotary zooming method means that the change of the focal length is achieved by turning the zoom ring and the manual focusing - by turning the separate focusing ring.

The push/pull zooming method means that the change of focal length and the manual focusing is achieved by one and the same ring. The change of focal length happens when the photographer moves the ring towards the mount or backwards and the rotation of the ring leads to change of focus.

Push/pull zooming allows for faster change of focal length, however conventional method based on the rotation of the zoom ring provides more accurate and smooth zooming.

Zoom lock

The lens features a zoom lock to keep the zoom ring fixed. This function is convenient for carrying a camera with the lens on a strap because it prevents the lens from extending.

Lens hood

A lens hood or lens shade is a device used on the end of a lens to block the sun or other light source in order to prevent glare and lens flare. Flare occurs when stray light strikes the front element of a lens and then bounces around within the lens. This stray light often comes from very bright light sources, such as the sun, bright studio lights, or a bright white background The light source itself may be in the lens' angle of view, but it doesn't have to be to cause a lens flare. It is only necessary that stray light from the bright light source enter the lens.

The geometry of the lens hood can vary from a plain cylindrical or conical section (much like a lamp shade) to a more complex shape, sometimes called a petal, tulip, or flower hood. These more complex shapes take into account the final image's shape and aspect ratio. This allows the lens hood to block stray light with the higher portions of the lens hood, while allowing more light into the corners of the image through the lowered portions of the hood, thereby reducing the amount of vignetting in the final image.

Lens hoods are more prominent in long focus lenses because they have a smaller viewing angle than that of wide-angle lenses. For wide angle lenses, the length of the hood (away from the end of the lens) cannot be as long as those for telephoto lenses, as a longer hood would enter the wider field of view of the lens.

Lens hoods that are supplied by the manufacturer of the lens are often designed to fit onto the matching lens facing either forward, for normal use, or backwards, so that the hood may be stored with the lens without occupying much additional space. Rubber lens hoods are flexible and generally collapse for storage. In addition, lens hoods can offer some degree of physical protection for the lens due to the hood extending farther than the lens itself.

Angle of view

Angle of view describes the angular extent of a given scene that is imaged by a camera. It is used interchangeably with the more general term field of view.

A camera's angle of view depends not only on the lens, but also on the sensor. Digital sensors are usually smaller than 35mm film, and this causes the lens to have a narrower angle of view than with 35mm film, by a constant factor for each sensor (called the crop factor).

This website calculates angles of view of lenses automatically by the following formula: 114.6 * arctan (21.622 / CF * FL),

where:

CF – crop-factor of a sensor,
FL – focal length of a lens.

Mount

A lens mount is an interface — mechanical and often also electrical — between a photographic camera body and a lens. It is confined to cameras where the body allows interchangeable lenses, most usually the rangefinder and SLR cameras.

A lens mount may be a screw-threaded type, a bayonet-type, or a breech-lock (friction lock) type. Modern still camera lens mounts are of the bayonet type, because the bayonet mechanism precisely aligns mechanical and electrical features between lens and body. Screw-threaded mounts are fragile and do not align the lens in a reliable rotational position.

Lens mounts of competing manufacturers (Canon, Nikon, Pentax, Sony etc.) are always incompatible. In addition to the mechanical and electrical interface variations, the flange focal distance from the lens mount to the film or sensor can also be different. These incompatibilities are probably due to the desire of manufacturers to lock in consumers to their brand.

Closest focusing distance

Distance from the focal plane (film or sensor) to the subject.

Closest working distance

Distance from the front of the lens to the subject.

Magnification ratio

Determines how large the subject will appear in the final image. A magnification ratio of 1:1 means that the image of the subject formed on the film or sensor will be the same size as the subject in real life. For this reason, a 1:1 ratio is often called "life-size". A lens is not considered to be "true" macro unless it can achieve at least life-size magnification.

Weight

Excluding caps and detachable accessories such as lens hood, close-up adapter, tripod adapter etc.

Maximum diameter x Length

Excluding caps and detachable accessories such as lens hood, close-up adapter, tripod adapter etc.

Distortion

A form of optical aberration, a deviation from rectilinear projection in which straight lines in a scene remain straight in an image.

Although distortion can be irregular or follow many patterns, the most commonly encountered distortions are radially symmetric, or approximately so, arising from the symmetry of a photographic lens. These radial distortions can usually be classified as either barrel distortions or pincushion distortions.

In barrel distortion, image magnification decreases with distance from the optical axis. The apparent effect is that of an image which has been mapped around a sphere (or barrel). Fisheye lenses, which take hemispherical views, utilize this type of distortion as a way to map an infinitely wide object plane into a finite image area. In a zoom lens barrel distortion appears in the middle of the lens's focal length range and is worst at the wide-angle end of the range.

In pincushion distortion, image magnification increases with the distance from the optical axis. The visible effect is that lines that do not go through the centre of the image are bowed inwards, towards the centre of the image, like a pincushion.

In photography, distortion is particularly associated with zoom lenses, particularly large-range zooms, but may also be found in prime lenses. Barrel distortion may be found in wide-angle lenses, and is often seen at the wide-angle end of zoom lenses, while pincushion distortion is often seen in older or low-end telephoto lenses.

Correction usually requires cropping out curved edges of the corrected image which can influence the composition. Moreover, correction leads to redistribution of image resolution – the center of the frame will lose some sharpness and the edges become sharper after the correction of pincushion distortion and vice versa, the center of the frame become sharper and the edges will lose some sharpness as the result of correction of barrel distortion. The results of correction could be especially noticeable for wide-angle lenses because most of lenses of such class suffer from resolution drop at the edges and especially at the corners of the frame. Thereby the correction should be performed only for those pictures which contain straight lines (f.e. images of architecture).

Vignetting

Vignetting is a reduction of an image's brightness or saturation at the periphery compared to the image center. Vignetting is often an unintended and undesired effect caused by camera settings or lens limitations. However, it is sometimes deliberately introduced for creative effect, such as to draw attention to the center of the frame. A photographer may deliberately choose a lens which is known to produce vignetting to obtain the effect, or it may be introduced with the use of special filters or post-processing procedures.

Correction of vignetting requires brightening of the edges and corners of the frame. Such correction however increases digital noise at the corresponding areas of the frame because digitally brightening an image amplifies both the signal and the noise equally. That’s why shooting at the maximum aperture should be avoided whenever possible since the all lenses have the strongest vignetting at their maximum aperture.

In some cases, the optical vignetting can be minimized by closing of the aperture by one or several stops. However even the significant closing of the aperture may not have the noticeable effect with some models of wide-angle lenses.

Fluorine coating

Helps keep lenses clean by reducing the possibility of dust and dirt adhering to the lens and by facilitating cleaning should the need arise. Applied to the outer surface of the front and/or rear lens elements over multi-coatings.

Floating element system

Provides correction of aberrations and ensures constantly high image quality at the entire range of focusing distances from infinity down to the closest focusing distance. It is particularly effective for the correction of field curvature that tends to occur with large-aperture, wide-angle lenses when shooting at close ranges.

Non-retrofocus lens

The lens was designed for use with 35mm film SLR cameras with the mirror locked in the up position. The lens extended into the SLR's mirror box when mounted. Mirror lock-up must be activated prior to mounting the lens; otherwise its rearmost element would be in the way as the mirror flipped up and down during exposure. A separate optical viewfinder had to be mounted on the accessory shoe to confirm angle of view, because when the mirror is in the up and locked position, the subject is no longer visible through the viewfinder.

Spherical aberration

Because of the spherical aberration the parallel light rays passing through the edge of the lens converge at the focal point closer to the lens than the rays passing through the lens center. Large aperture lenses suffer from stronger spherical aberration. Rays of light passing near the optical axis form a sharp point on the image sensor of a camera but under the influence of the peripheral rays of light the point light source receives a uniform halo. Spherical aberration affects the whole image field from the center to the edges and results in a blurred image with lower contrast.

The correction of spherical aberration of spherical lenses is very complex and does not ensure its complete elimination. The residual aberration can be significantly reduced by closing of the aperture, because the edges of the lens are thus blocked. The only effective way to substantially compensate for the spherical aberration at the maximum relative aperture of the large aperture lens is the use of aspherical elements. Uncorrected spherical aberration can cause a focus shift.

Bokeh

Bokeh is a quite subjective concept as the perception of the image depends on the viewer. Some like "nervous" bokeh with twisted or doubled background. Some prefer out-of-focus highlights to take the form of a polygonal shape. However most of the people like the following characteristics:

Filters

There are two basic types of lens filters - circular that screw directly on the filter thread in front of the lens, and square ones, which slot into a filter holder.

Circular screw-on filters protect the surface of the front lens element against dust, moisture, fingerprints, scratches and bumps. Square gelatin filters are dropped into place in slot that keeps it flat and parallel to the focal plane in order to maintain optimal image quality. Drop-in filters are mostly used in super telephoto lenses due to the large size of the front lens element.

The primary function of lens filters is to improve the image quality and/or produce special effects.

Format

Format refers to the shape and size of film or image sensor.

35mm is the common name of the 36x24mm film format or image sensor format. It has an aspect ratio of 3:2, and a diagonal measurement of approximately 43mm. The name originates with the total width of the 135 film which was the primary medium of the format prior to the invention of the full frame digital SLR. Historically the 35mm format was sometimes called small format to distinguish it from the medium and large formats.

APS-C is an image sensor format approximately equivalent in size to the film negatives of 25.1x16.7mm with an aspect ratio of 3:2.

Weather sealing

Weather sealed lenses contain a rubber material which is inserted in between each externally exposed part (manual focus and zoom rings, buttons, switch panels etc.) to ensure it is properly sealed against dust and moisture.

Lenses that accept front mounted filters typically do not have gaskets behind the filter mount. It is recommended to use a filter for complete weather resistance when desired.

Diaphragm type

SLR cameras require stopping down to the chosen aperture immediately before exposure, in order to permit viewing and focusing at full aperture up to the moment the shutter is released.

Historically, there are four different types of diaphragm:

Manual – the diaphragm must be stopped down manually by rotating the detent aperture ring,

Pre-set – the lens has two rings, one is for pre-setting, while the other is for normal diaphragm adjustment. The first ring must be set at the desired aperture, the second ring then should be fully opened for focusing, and turned back for stop down to the pre-set value,

Semi-automatic – the lens features spring mechanism in the diaphragm, triggered by the shutter release, which stops down the diaphragm to the pre-set value. The spring needs to be reset manually after each exposure to re-open diaphragm to its maximum value,

Automatic – the actuating lever in the camera, operated by the shutter release, closes the diaphragm down during the shutter operation. On completion of the exposure, the diaphragm re-opens to its maximum value.

Hybrid IS

The image stabilizer has Hybrid IS technology which corrects not only angle but also shift camera shake, which is more pronounced in close-range shooting when a camera moves parallel to the imaging scene. Hybrid IS dramatically enhances the effects of image stabilization during shooting, including macro shooting, which had proven difficult for conventional image stabilization technologies.

Dynamic IS

The image stabilizer has Dynamic IS technology which especially effective when shooting while walking because it compensates strong camera shake. Dynamic IS activates automatically when the camera is set to movie shooting.

Mode 1

Corrects vertical and horizontal camera shake. Mainly effective for shooting still subjects.

Mode 2

Corrects vertical camera shake during following shots in a horizontal direction. Corrects horizontal camera shake during following shots in a vertical direction.

Mode 2

Corrects vertical camera shake during following shots in a horizontal direction.

Mode 2 (Intelligent OS)

The lens incorporates Intelligent OS with algorithm capable of panning in all directions. In Mode 2, the movements of subjects can be captured with panning effects even when the camera is moved horizontally, vertically, or diagonally — regardless of the position of the lens.

Mode 3

Corrects camera shake only during exposure. During panning shots, corrects camera shake during exposure only in one direction the same as Mode 2. Effective for following fast and irregulary moving subjects.

Panning Detection

The image stabilizer automatically detects panning and then corrects camera shake only in one direction

Tripod Detection

It is often thought that image blur caused by camera shake can be prevented by using a tripod. Actually, however, even using a tripod may result in image blur because of tripod vibration caused by mirror or shutter movement at the time of exposure. The image stabilizer automatically differentiates the frequency of the vibration from that of camera shake, and changes algorithm to correct image blur caused by slight tripod vibration.

VR NORMAL

Corrects vertical and horizontal camera shake. Automatically detects panning and then corrects camera shake only in one direction.

VR ACTIVE

Corrects vertical and horizontal camera shake when shooting from a moving vehicle, or some other unstable position. Panning is not detected.

VR SPORT

Allows a continuous shooting frame rate and release time lag similar to those that are possible when image stabilizer is turned off. Automatically detects panning and then corrects camera shake only in one direction.

VR TRIPOD

It is often thought that image blur caused by camera shake can be prevented by using a tripod. Actually, however, even using a tripod may result in image blur because of tripod vibration caused by mirror or shutter movement at the time of exposure. The image stabilizer automatically differentiates the frequency of the vibration from that of camera shake, and changes algorithm to correct image blur caused by slight tripod vibration.

SONY E BAYONET MOUNT

Designed by: Sony Corporation
Announced: 2010
Discontinued: None
Maximum format: 35mm full frame
Camera type: Mirrorless
AF support: Yes
Flange focal distance: 18mm

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