Bronica ETRSi

Medium format MF film SLR camera


Production details:
Announced:December 1988
System: Bronica ETR (1976)
Maximum format:Medium format 6x4.5
Film type:120 roll film
220 roll film
Mount and Flange focal distance:Bronica ETR [69mm]
Type:In-lens leaf shutter
Exposure metering:None
Exposure modes:Manual
Physical characteristics:

Manufacturer description #1

Type: 4.5cm x 6cm format lens shutter single-lens reflex camera, with interchangeable lens, film back, finder and focusing screen systems

Frame size: 42.5mm x 55.1mm (side/length ratio of 1:1.29 closely matches standard paper and reproduction sizes)

Film: 120 roll film (15 exposures); 220 roll film (30 exposures); 135 cartridge-loaded film; and Polaroid Land pack film. (Exclusive film backs for each film type.)

Lens mount: Exclusive four claw Bronica ETR bayonet mount

Lens diaphragm: Fully automatic instant reopening lens diaphragm action; equal-distant aperture scale graduations; depth of field previewing

Shutter: Electronic control SEIKO #0 between-lens leaf shutter; shutter speeds 8 sec. to 1/500 sec. plus T (time exposures); intermediate settings not possible; mechanical control setting 1/500 sec.

Film winding: Film winding crank; one complete forward revlution or ratcheted winding action

Mirror lock-up: Possible with mirror lock-up lever

Multiple exposure: Possible with multiple exposure lever; red warning sign in finder

Film back: Daylight loading interchangeable type, exclusive film backs for 120, 220 and 135 roll films and Polarod Land pack film

Finder: Interchangeable finder system; 94% of actual field of view (remains unchanged with different finders); choice of four optional finders, or Waist-Level Finder E, AE-II Finder E, Rotary Viewfinder E and Prism Finder E

Focusing screen: Interchangeable type. Standard screen has matte spot

Flash synchronization: X-setting (up to 1/500 sec.); auto-flash control based on direct light measurement at the film plane is possible with optional SCA System Adapter

Battery checking: Red-colored LED lights up within screen area when battery check button is depressed, if there is sufficient power; also doubles as shutter closing signal

Battery: Single 6-volt silver oxide or alkaline-manganese battery; also powers AE-II Finder E, when attached

Manufacturer description #2


The ETRSi fulfills the idealistic requirements of serious photographers looking for more vivid image reproductions. Extremely fine details and subtle nuances are all conveyed to the film. The 6 x 4.5cm size negative frame, which is about 2.7 times larger than the 35mm format, makes possible superb image quality, while the large-size viewing screen contains all vital information. This especially makes the format a valuable one for the professional photographer. The superior depiction of the ETRSi greatly increases the scope of the photographer in the pursuit of new image expressions.

Creative picture-taking can not take place, even when the powers of expression are rich if there are too many limitations placed on the photographer. In the case of the ETRSi however, special importance has been placed on this point and there is a high degree of system flexibility. Not only has acompact and light-weight camera been developed, based on Bronica's exclusive lens shutter system, but Bronica has advanced the use of electronics in various sophisticated functions, resulting in enhanced precision. And, the pursuit of greater holding stability has also lead to an improvement in handling ease. Furthermore, the very flexible "system" design of the ETRSi, in which lenses, finders, film backs and focusing screens can be freely exchanged, as well as a full range of valuable accessories makes it possible to customize the "system" to match the user's intention in picture-taking. These versatile functions in avery compact camera have been successful in greatly increasing the creative freedom in photography.

Image presentations of the highest quality has been the consistent goal of Bronica. It is also the reason for pursuing the large negative frame size, such as the SQ Series in the 6x 6cm format, the GS-1 in the 6 x 7cm format and now the 6 x 4.5cm format of the ETRSi. By adding greater handling ease to the medium format camera, which already boasts superior powers of portrayal, even more varied image presentation are now possible. And, to attain such high goals, no technical effort has been spared. This is a concept born from Bronica's basic thinking, that the creative power of the photographer is the most important element and must be extended as much as possible with the assistance of modern technology.


For a more distinct expression of the photographer's intentions, there is coexistence of high image quality with the superior power of portrayal of the 6 x 4.5cm size along with excellent handling ease. This design concept is present with the ETRSi. An extremely high system capability has been attained, in which it is possible to choose acamera system suited for the photographer's individual purpose, by simply combining various system accessories with the main camera body. This has been made possible by acomplete fusion of technical knowledge gained by Bronica through thirty years as an exclusive maker of medium precision format cameras and the most advanced electronic technologies.

The Zenzanon-PE series lenses are based on the original design technology of the Zenzanon-PG lenses (GS-1; 6x7) and Zenzanon-PS lenses (SQ-Ai; 6x6), which are already noted as being among the sharpest in the world. The Zenzanon-PE lenses also take full advantage of MTF technology in their design, and have overall improvement in optical performance, such as resolving power, contrast, etc. Bronica's exclusive multi-layer coating increases optical transmittance, while further suppressing ghost and flare. Matched color fidelity and unadulterated color balance are faithfully conveyed from the original image. The electronically controlled Seiko #0 lens shutter offers exacting shutter speed capability from lens to lens, as the timer is in the camera body. In addition, the shutter synchronizes at all speeds up to 1/500 sec. Now, the ultimate in state of the art lens quality is available for each of the proven camera systems.

There is complete finder interchangeability to match requirements for a wide variety of image expressions, such as waist-level or eye-level view-focusing, even low angle shooting. Also available, aperture-priority auto-exposure with TTL-metering with the AE-II Prism Finder E, which, together with the great handling ease of the ETRSi, vastly increases the scope of image expessions possible. Manual exposure control is also present, thus providing the greatest freedom in overall image creativity.

Film back interchangeability makes possible the handling ease and wide variety of image expressions of the ETRSi. With one-touch exchanges, film type and frame size can match the photographic purpose or conditions. And, there is complete freedom in film back exchanges, even midway in the roll, or in daylight, all without limitations, while mistakes are also effectively prevented.

Simple, fast film winding operations makes it possible to concentrate on the subject, when following fastbreaking actions, with fast shooting action and handling ease greatly improved in the new, lightweight Motor Winder Ei.

One of the main characteristics of the medium format camera is the varied image expessions. Full of originality, these image can be obtained by utilizing the many photo technics which are available, such as multiple exposures, etc. Thus, in addition to the high image quality of the ETRSi, it is possible for the photographer to enjoy the full attraction of the medium format camera with varied new mechanisms.

Because of the importance of fl ash pho- tography for both professionals and advanced users, Bronica has developed an exclusive C.C.C. (Current Control Center) System for auto-flash operations, based on direct metering at the film plane, when coupled to SCA System electronic flash units from Metz (Mecablitz) of West Germany. The SCA System becomes effective when the SCA System Adapter (386) is used and also provides ready-flash signal and auto-checking confirmation in the viewfinder area.

Mechanical shock has been greatly reduced, by eliminating mechanical vibrations, while vibrations due to the reflex mirror action has been eliminated with a new mirror lock-up system. Vibration-free picture-taking is ideal when using aslow shutter speed, taking long telephoto shots and close-ups.

Multiple exposures, in which two or more exposures are made on the same frame, is an unique photographic effect which is most effective in the medium format because of the high image quality and large negative area. The multiple exposure lever of the ETRSi is not only easy to use but a red warning Signal appears in the finder when in use, to avoid mistakes.

Long shutter speeds can be set freely, to match the intentions of the user, thus increasing the possibilities for producing new image expressions. Long time exposures can be used for photographing merchandises, for producing unique photo images, or for special photographic effects coupled to the electronic flash, which means that new photo technics are possible with the ETRSi.

The ETRSi is based on the "system" design, with lenses, finders, film backs, winders, etc., used, as required, in combination with the main camera body for producing the "system" camera required by the user. And, a full range of versatile accessories are also available for extending the "system" camera to match photographic requirements.

Manufacturer description #3






Commack, New York, October 1, 2004 – Mr. Takashi Inoue, president of Tamron USA, Inc. announced the discontinuation of Bronica ETR-Si, SQ-Ai, SQ-B and GS-1 cameras and accessories as of October 31, 2004 in the U.S. market.

"Since the advent of digital photography, medium format sales have declined at a rapid pace. Imports today are just a fraction of what they were even two years ago," stated Inoue. "For Bronica, that slip has been faster since our core customer base, portrait and wedding photographers, has adapted well to digital SLR equipment."

"These photographers are now providing customers with a quality and cost-efficient product that has virtually eliminated their need for the higher quality results that medium format film or digital backs can provide," added Stacie Errera, Chief Marketing Officer. "While some customers are faithful to the format, the current sales volume and devastating purchasing forecasts cannot sustain the production of Bronica SLR products."

Tak Inoue stated that with the discontinuation of Bronica, the company is now in a better position to dedicate even more resources to developing optics for the digital age, particularly those for digital SLR cameras, currently the fastest growing segment of camera products according to industry analysts.

Customers may continue to purchase Bronica ETR-Si, SQ-Ai, SQ-B, and GS-1 products through 11/15/04 and qualify for the current Bronica SLR rebates. Tamron will post a list of dealers with substantial Bronica inventory and users are suggested to contact these dealers to purchase equipment. If the dealer does not have what the customer is looking for, Tamron USA, Inc. will make special accommodation sales to the customer directly at the current published Minimum Advertised Price less any applicable rebate. After 11/15/04, Tamron USA, Inc. will no longer sell any Bronica SLR inventory to customers. In order to claim a rebate for merchandise purchased through a dealer by 11/15/04, Tamron USA, Inc. must receive the redemption request by 11/30/04 to qualify. Purchases made after 11/15/04 at a dealer with inventory will not be applicable for any rebates.

The Bronica RF645 Medium Format Rangefinder will continue to be distributed and Tamron USA, Inc. will offer the current rebates on that product line.

Repair service will continue for seven years as is mandated by law. Any new Bronica SLR equipment purchased after October 31, 2004 — the official date of discontinuation — (through Tamron or any dealer by 11/15/04 or any dealer thereafter) will carry a one year limited warranty from date of purchase. However, all warranty and out-of-warranty repair service obligations will cease on October 31, 2011, regardless of purchase date.

From the editor

The weight and dimensions are indicated for the camera body with the Zenzanon-PE 75mm F/2.8 lens mounted.

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Chromatic aberration

There are two kinds of chromatic aberration: longitudinal and lateral. Longitudinal chromatic aberration is a variation in location of the image plane with changes in wave lengths. It produces the image point surrounded by different colors which result in a blurred image in black-and-white pictures. Lateral chromatic aberration is a variation in image size or magnification with wave length. This aberration does not appear at axial image points but toward the surrounding area, proportional to the distance from the center of the image field. Stopping down the lens has only a limited effect on these aberrations.

Spherical aberration

Spherical aberration is caused because the lens is round and the film or image sensor is flat. Light entering the edge of the lens is more severely refracted than light entering the center of the lens. This results in a blurred image, and also causes flare (non-image forming internal reflections). Stopping down the lens minimizes spherical aberration and flare, but introduces diffraction.


Astigmatism in a lens causes a point in the subject to be reproduced as a line in the image. The effect becomes worse towards the corner of the image. Stopping down the lens has very little effect.


Coma in a lens causes a circular shape in the subject to be reproduced as an oval shape in the image. Stopping down the lens has almost no effect.

Curvature of field

Curvature of field is the inability of a lens to produce a flat image of a flat subject. The image is formed instead on a curved surface. If the center of the image is in focus, the edges are out of focus and vice versa. Stopping down the lens has a limited effect.


Distortion is the inability of a lens to capture lines as straight across the entire image area. Barrel distortion causes straight lines at the edges of the frame to bow toward the center of the image, producing a barrel shape. Pincushion distortion causes straight lines at the edges of the frame to curve in toward the lens axis. Distortion, whether barrel or pincushion type, is caused by differences in magnification; stopping down the lens has no effect at all.

The term "distortion" is also sometimes used instead of the term "aberration". In this case, other types of optical aberrations may also be meant, not necessarily geometric distortion.


Classically, light is thought of as always traveling in straight lines, but in reality, light waves tend to bend around nearby barriers, spreading out in the process. This phenomenon is known as diffraction and occurs when a light wave passes by a corner or through an opening. Diffraction plays a paramount role in limiting the resolving power of any lens.


Doublet is a lens design comprised of two elements grouped together. Sometimes the two elements are cemented together, and other times they are separated by an air gap. Examples of this type of lens include achromatic close-up lenses.

Dynamic range

Dynamic range is the maximum range of tones, from darkest shadows to brightest highlights, that can be produced by a device or perceived in an image. Also called tonal range.

Resolving power

Resolving power is the ability of a lens, photographic emulsion or imaging sensor to distinguish fine detail. Resolving power is expressed in terms of lines per millimeter that are distinctly recorded in the final image.


Vignetting is the darkening of the corners of an image relative to the center of the image. There are three types of vignetting: optical, mechanical, and natural vignetting.

Optical vignetting is caused by the physical dimensions of a multi-element lens. Rear elements are shaded by elements in front of them, which reduces the effective lens opening for off-axis incident light. The result is a gradual decrease of the light intensity towards the image periphery. Optical vignetting is sensitive to the aperture and can be completely cured by stopping down the lens. Two or three stops are usually sufficient.

Mechanical vignetting occurs when light beams are partially blocked by external objects such as thick or stacked filters, secondary lenses, and improper lens hoods.

Natural vignetting (also known as natural illumination falloff) is not due to the blocking of light rays. The falloff is approximated by the "cosine fourth" law of illumination falloff. Wide-angle rangefinder designs are particularly prone to natural vignetting. Stopping down the lens cannot cure it.


Bright shapes or lack of contrast caused when light is scattered by the surface of the lens or reflected off the interior surfaces of the lens barrel. This is most often seen when the lens is pointed toward the sun or another bright light source. Flare can be minimized by using anti-reflection coatings, light baffles, or a lens hood.


Glowing patches of light that appear in a photograph due to lens flare.

Retrofocus design

Design with negative lens group(s) positioned in front of the diaphragm and positive lens group(s) positioned at the rear of the diaphragm. This provides a short focal length with a long back focus or lens-to-film distance, allowing for movement of the reflex mirror in SLR cameras. Sometimes called an inverted telephoto lens.


A photographic lens completely corrected for the three main optical aberrations: spherical aberration, coma, and astigmatism.

By the mid-20th century, the vast majority of lenses were close to being anastigmatic, so most manufacturers stopped including this characteristic in lens names and/or descriptions and focused on advertising other features (anti-reflection coating, for example).

Rectilinear design

Design that does not introduce significant distortion, especially ultra-wide angle lenses that preserve straight lines and do not curve them (unlike a fisheye lens, for instance).

Focus shift

A change in the position of the plane of optimal focus, generally due to a change in focal length when using a zoom lens, and in some lenses, with a change in aperture.


The amount of light that passes through a lens without being either absorbed by the glass or being reflected by glass/air surfaces.

Modulation Transfer Function (MTF)

When optical designers attempt to compare the performance of optical systems, a commonly used measure is the modulation transfer function (MTF).

The components of MTF are:

The MTF of a lens is a measurement of its ability to transfer contrast at a particular resolution from the object to the image. In other words, MTF is a way to incorporate resolution and contrast into a single specification.

Knowing the MTF curves of each photographic lens and camera sensor within a system allows a designer to make the appropriate selection when optimizing for a particular resolution.

Veiling glare

Lens flare that causes loss of contrast over part or all of the image.

Anti-reflection coating

When light enters or exits an uncoated lens approximately 5% of the light is reflected back at each lens-air boundary due to the difference in refractive index. This reflected light causes flare and ghosting, which results in deterioration of image quality. To counter this, a vapor-deposited coating that reduces light reflection is applied to the lens surface. Early coatings consisted of a single thin film with the correct refractive index differences to cancel out reflections. Multi-layer coatings, introduced in the early 1970s, are made up of several such films.

Benefits of anti-reflection coating:

Circular fisheye

Produces a 180° angle of view in all directions (horizontal, vertical and diagonal).

The image circle of the lens is inscribed in the image frame.

Diagonal (full-frame) fisheye

Covers the entire image frame. For this reason diagonal fisheye lenses are often called full-frame fisheyes.

Extension ring

Extension rings can be used singly or in combination to vary the reproduction ratio of lenses. They are mounted between the camera body and the lens. As a rule, the effect becomes stronger the shorter the focal length of the lens in use, and the longer the focal length of the extension ring.

View camera

A large-format camera with a ground-glass viewfinder at the image plane for viewing and focusing. The photographer must stick his head under a cloth hood in order to see the image projected on the ground glass. Because of their 4x5-inch (or larger) negatives, these cameras can produce extremely high-quality results. View cameras also usually support movements.

135 cartridge-loaded film

43.27 24 36
  • Introduced: 1934
  • Frame size: 36 × 24mm
  • Aspect ratio: 3:2
  • Diagonal: 43.27mm
  • Area: 864mm2
  • Double perforated
  • 8 perforations per frame

120 roll film

71.22 44 56
  • Introduced: 1901
  • Frame size: 56 × 44mm
  • Aspect ratio: 11:14
  • Diagonal: 71.22mm
  • Area: 2464mm2
  • Unperforated

120 roll film

79.2 56 56
  • Introduced: 1901
  • Frame size: 56 × 56mm
  • Aspect ratio: 1:1
  • Diagonal: 79.2mm
  • Area: 3136mm2
  • Unperforated

120 roll film

89.64 56 70
  • Introduced: 1901
  • Frame size: 70 × 56mm
  • Aspect ratio: 5:4
  • Diagonal: 89.64mm
  • Area: 3920mm2
  • Unperforated

220 roll film

71.22 44 56
  • Introduced: 1965
  • Frame size: 56 × 44mm
  • Aspect ratio: 11:14
  • Diagonal: 71.22mm
  • Area: 2464mm2
  • Unperforated
  • Double the length of 120 roll film

220 roll film

79.2 56 56
  • Introduced: 1965
  • Frame size: 56 × 56mm
  • Aspect ratio: 1:1
  • Diagonal: 79.2mm
  • Area: 3136mm2
  • Unperforated
  • Double the length of 120 roll film

220 roll film

89.64 56 70
  • Introduced: 1965
  • Frame size: 70 × 56mm
  • Aspect ratio: 5:4
  • Diagonal: 89.64mm
  • Area: 3920mm2
  • Unperforated
  • Double the length of 120 roll film

Shutter speed ring with "F" setting

The "F" setting disengages the leaf shutter and is set when using only the focal plane shutter in the camera body.

Catch for disengaging cross-coupling

The shutter and diaphragm settings are cross-coupled so that the diaphragm opens to a corresponding degree when faster shutter speeds are selected. The cross-coupling can be disengaged at the press of a catch.

Cross-coupling button

With the cross-coupling button depressed speed/aperture combinations can be altered without changing the Exposure Value setting.

M & X sync

The shutter is fully synchronized for M- and X-settings so that you can work with flash at all shutter speeds.

In M-sync, the shutter closes the flash-firing circuit slightly before it is fully open to catch the flash at maximum intensity. The M-setting is used for Class M flash bulbs.

In X-sync, the flash takes place when the shutter is fully opened. The X-setting is used for electronic flash.

X sync

The shutter is fully synchronized for X-setting so that you can work with flash at all shutter speeds.

In X-sync, the flash takes place when the shutter is fully opened. The X-setting is used for electronic flash.

Unable to follow the link

You are already on the page dedicated to this lens.

Cannot perform comparison

Cannot compare the lens to itself.

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.

Original name

Lens name as indicated on the lens barrel (usually on the front ring). With lenses from film era, may vary slightly from batch to batch.


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.

Medium format is a film format or image sensor format larger than 36x24mm (35mm) but smaller than 4x5in (large format).

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.

As the focal length changes, the angle of view also changes. The shorter the focal length (eg 18mm), the wider the angle of view. Conversely, the longer the focal length (eg 55mm), the smaller the angle of view.

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

This website does not use the angles of view provided by lens manufacturers, but calculates them automatically by the following formula: 114.6 * arctan (21.622 / CF * FL),


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


A lens mount is an interface — mechanical and often also electrical — between a camera body and a lens.

A lens mount may be a screw-threaded type, a bayonet-type, or a breech-lock type. Modern camera lens mounts are of the bayonet type, because the bayonet mechanism precisely aligns mechanical and electrical features between lens and body, unlike screw-threaded mounts.

Lens mounts of competing manufacturers (Canon, Leica, Nikon, Pentax, Sony etc.) are always incompatible. In addition to the mechanical and electrical interface variations, the flange focal distance (distance from the mechanical rear end surface of the lens mount to the focal plane) is also different.

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.

Focal length

The focal length is the factor that determines the size of the image reproduced on the focal plane, picture angle which covers the area of the subject to be photographed, depth of field, etc.


The largest opening or stop at which a lens can be used is referred to as the speed of the lens. The larger the maximum aperture is, the faster the lens is considered to be. Lenses that offer a large maximum aperture are commonly referred to as fast lenses, and lenses with smaller maximum aperture are regarded as slow.

In low-light situations, having a wider maximum aperture means that you can shoot at a faster shutter speed or work at a lower ISO, or both.

Closest focusing distance

The minimum distance from the focal plane (film or sensor) to the subject where the lens is still able to focus.

Closest working distance

The distance from the front edge of the lens to the subject at the maximum magnification.

Magnification ratio

Determines how large the subject will appear in the final image. Magnification is expressed as a ratio. For example, 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".

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.

Manual diaphragm

The diaphragm must be stopped down manually by rotating the detent aperture ring.

Preset diaphragm

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 diaphragm

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 diaphragm

The camera automatically closes the diaphragm down during the shutter operation. On completion of the exposure, the diaphragm re-opens to its maximum value.

Fixed diaphragm

The aperture setting is fixed at F/ on this lens, and cannot be adjusted.

Number of blades

As a general rule, the more blades that are used to create the aperture opening in the lens, the rounder the out-of-focus highlights will be.

Some lenses are designed with curved diaphragm blades, so the roundness of the aperture comes not from the number of blades, but from their shape. However, the fewer blades the diaphragm has, the more difficult it is to form a circle, regardless of rounded edges.

At maximum aperture, the opening will be circular regardless of the number of blades.


Excluding case or pouch, caps and other detachable accessories (lens hood, close-up adapter, tripod adapter etc.).

Maximum diameter x Length

Excluding case or pouch, caps and other detachable accessories (lens hood, close-up adapter, tripod adapter etc.).

For lenses with collapsible design, the length is indicated for the working (retracted) state.

Weather sealing

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.

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 lens element over multi-coatings.


Lens filters are accessories that can protect lenses from dirt and damage, enhance colors, minimize glare and reflections, and add creative effects to images.

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 geometry of the lens hood can vary from a plain cylindrical or conical section to a more complex shape, sometimes called a petal, tulip, or flower hood. 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.

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 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 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. In addition, lens hoods can offer some degree of physical protection for the lens due to the hood extending farther than the lens itself.


Teleconverters increase the effective focal length of lenses. They also usually maintain the closest focusing distance of lenses, thus increasing the magnification significantly. A lens combined with a teleconverter is normally smaller, lighter and cheaper than a "direct" telephoto lens of the same focal length and speed.

Teleconverters are a convenient way of enhancing telephoto capability, but it comes at a cost − reduced maximum aperture. Also, since teleconverters magnify every detail in the image, they logically also magnify residual aberrations of the lens.

Lens caps

Scratched lens surfaces can spoil the definition and contrast of even the finest lenses. Lens covers are the best and most inexpensive protection available against dust, moisture and abrasion. Safeguard lens elements - both front and rear - whenever the lens is not in use.