Exakta A

Medium format MF film SLR camera

Specification

Production details:
Announced:1933
System: VP Exakta (1933)
Format:
Maximum format:Medium format 6.5x4
Film type:127 roll film
Mount and Flange focal distance:VP Exakta
Shutter:
Type:Focal-plane
Model:Mechanical
Speeds:1/25 - 1/1000 + B, Z
Exposure:
Exposure metering:None
Exposure modes:Manual
Physical characteristics:
Weight:750g
Dimensions:150x65x50mm

Manufacturer description #1

Exakta is an unusual novelty in the field of miniature cameras. Its design is such that it gives the maximum camera effectiveness in the smallest possible space.

It is a mirror reflex using roll film 1 5/8 x 2 1/2 inches, which is commonly used in all Vest-Pocket cameras, and is usualy supplied 8 exposures to the roll. Most miniature cameras that do not have the reflex feature do not possess the exactness of focus of the Exakta. With this camera it is not necessary to use either a depth of focus scale or a distance meter. When examining the image on the ground glass one can determine the exact depth of focus that the lens gives and use the diaphragm accordingly. This feature makes it possible to focus and compose the image much more satisfactorily than with the small finders usually supplied on Miniature cameras. It is also possible to examine the image up to the very last second before making exposures. The film spool and focal plane shutter with which this camera is equipped are synchronized so that it is impossible to make a double exposure.

The long experience of the makers of this camera in constructing mirror reflex cameras has stood them in good stead in perfecting this instrument.

Manufacturer description #2

The "Exakta" being a direct Reflex Camera, the picture seen in the finder mirror is exactly the same as the one the lens will produce on the film, exact size and exact in detail. The same knob that winds the film to the next number also sets the shutter, and double exposures are quite impossible.

In the Model A the Ihagee Patent Safety Blind Focal Plane Shutter allows for speeds from 1/25th to 1/1,000th second, also time and bulb. The Model B is fitted with an extra control giving instantaneous exposures from 1/25th ot 1/1,000th second, short and long time exposures from 1/10th, 1/2 to 12 seconds. Delayed action release for exposures from 1/1,000th to 6 seconds. The delayed action control allows 12 seconds to elapse after the release has been pressed before the shutter operates.

In addition to the direct reflex image the picture can also be seen at eye level by means of an auxiliary mirror; and a magnifier is incorporated for extra fine focussing, also frame finder for use when necessary.

The focussing is effected by a rapid Helical Screw and the scale is engraved from infinity up to four feet.

Body made entirely of metal, leather covered, with spring safety cover to the film recording aperture, for use with Panchromatic films, and fitted with Tripod Bush and Cable Release.

Manufacturer description #3

Focal plane shutter, self-capping, instantaneous speeds from 1/25th to 1/1000th sec. can be read at once, time exposures for any length. Interchangeable lenses.

From the Classic Camera magazine (November 2002)

In 1932, the same year it was celebrating its twentieth year of activity in its headquarters in Marcolini Strasse in Dresden, Johan Steenbergen's Ihagee company began production on an extraordinary reflex camera for 127 roll film in the then-popular 6.5x4cm format known as Vest Pocket.

The camera was officially presented to the public at the LeipzigerMesse in 1933 with the name Exakta and was equipped with a folding waist level finder, focal plane shutter, speeds up to 1/1000 sec and removable lens. The Exakta offered a number of new and interesting structural features, both from a technical/functional point of view as well as in its appearance.

The Exakta was designed by Karl Nuchterlein for Ihagee on the basis of a number of very original ideas that took root quite independently from the roll and plate reflex cameras available on the market in the late 1920s. The Exakta was different from the ungainly Ensign Roll Film Reflex made by the English firm Houghton, and was very different from the twin-lens reflexes so tremendously popular at the time. Compared with Ihagee's traditional reflex output - the folding Klappreflex for 6.5x9cm to 10x15cm plates, the Nachtreflex for 4.5x6cm or 6.5x9cm plates and the economical 6x6cm Roll Paff - the Exakta represented a major leap in quality. Exakta's original features included the choice of roll film instead of plates and, above all, 127 film which was much narrower than 120 roll film. Even the choice of the long, narrow 4x6.5cm Vest Pocket format that did not correspond with any print paper size was something new compared with the traditional square format of the Rolleiflex and perhaps drew on the success of the similar Leica format. The Exakta was designed without taking into consideration the problems of taking vertical shots and the paper wastage already evident in the Leica 24x26mm format. Finally, the Exakta was original for the layout of its main controls, such as the wind button and shutter speed dial on the left side of the top plate instead of the right. The shutter release button was placed in the unusual position on the front of the camera, but always on the left. Seemingly designed for left-handed photographers, the Exakta was particularly flat and elongated in shape with the two sides of the front sharply slanted towards the front lens panel. The camera had an unusual trapezoid prism shape with the shorter base towards the front. This shape was never imitated by any other camera and, in the end, was what distinguished the entire line of Exakta reflex cameras, whether Vest Pocket or 35mm format. The same shape was firmly adhered to for the Exakta 35mm cameras produced in the post-war period up to the early '70s.

Light and manageable, the Exakta was equipped with a large folding waist level finder, focal plane shutter in rubberized silk and a lens equipped with a large focusing helical with infinity locking lever. The lens mount thread size was 39.5mm with a pitch of 0.5mm, fairly similar to that used on the Leica. At time of purchase, the buyer could choose from five different 75mm focal length lenses: an Exaktar, a Primotar or a Tessar with a speed of f/3.5, or a f/2.8 Xenar or Tessar. The lens was removable but not interchangeable due to the lack of alternative focal lengths, and the possibility of mounting lenses by other manufacturers or with different speeds, was more of an advantage for the manufacturer or dealer than the photographer. The back of the Exakta could be opened from the side with a latch on the right and had the classic red window to check film advance and frame count. The camera body, like most cameras of the era, had a black paint finish.

Over the course of 1933, two versions of the Exakta VP were produced simultaneously that were identical in appearance but with different features and price tag. The first Exakta was identified as the Exakta A with seven shutter speeds (1/25, 50, 100, 200, 300, 600 and 1000 plus B and time exposure settings) and with the right side of its top plate completely smooth, without any controls. The second Exakta was called the Exakta B and had the same shutter speed dial, but on the opposite side of the top plate it had a large knob used to select slow speeds from 1/10, 1/2 and 1, 2, 3, 4, 5, 6, 9, 10, 12 seconds. The same knob was used to load the self timer with up to a 6 second delay. These two Exaktas were manufactured in parallel for all of 1933, but the next year both were replaced by two cameras that offered the same shutter speeds, but with a fast wind lever instead of the clumsy knob. Above all, the 1934 Exaktas were equipped with a new screw mount for lenses just slightly wider than before, 39.8mm, and more solid with a pitch of 0.75mm. The new mount made it possible to interchange lenses and mount an entire series of fast lenses and telephoto lenses on the Exakta. In addition to these technical changes, there were also some styling modifications. Although the controls remained on the left front, the infinity locking lever was moved to the left of the lens changing catch. On the finder cover next to the Ihagee name, the company logo - a small sun inside of a half-moon - was engraved. At virtually the same time, the back was modified with a sliding door to protect the red window that was only opened to check the film advance. These changes were not made at the same time or all together, so it is possible to find Exakta cameras with the old wind knob and new lens mount, or with the release lever on the right and new type of back, or vice versa. Collectors have identified various versions of the Exakta A and B manufactured over the years 1933 and 1934, all characterized by the lack of the synch sockets on the front.

In 1935, Exakta output was updated with the addition of a two pin socket on the front for use with a Vacublitz flash. This was something entirely new in the camera field and the Vacublitz company released a series of reflectors with flash bulbs designed and created expressly for use with the Exakta Vest Pocket. The Exakta A, Exakta B and Exakta Night made use of this attractive feature in the new models built between 1935 and 1936. The two pin socket was modified in 1937 with the addition of a third hole aligned vertically with the synch sockets, but, unlike the latter, was not an electrical contact, merely a mechanical connection for the flash arm. Beneficiaries of this feature were the Exakta B and Exakta Night, but the same type of contact can also appear on the more economical Exakta A and was even used on some Exaktas made before 1935.

The rapid proliferation of its models and variants was symptomatic of a period characterized by rigorous experimentation and technical progress and the Exakta Vest Pocket left its mark on a short but intensely-active era that, unfortunately, was interrupted by the tragedy of the war. The Exakta Vest Pocket remained in production for just eight years, perhaps until 1940, handing over its legacy in full to the small Kine Exakta for 35 mm film. With war imminent, production of the Exakta Vest Pocket was halted, never to be restarted. Despite the fact that the Exakta VP offered performance levels that, in terms of lens speed, were equal to the Ermanox, in terms of versatility to the Leica and for precision to the Rolleiflex, in the post-war period there was no one willing to continue their production or imitate them, either in Germany or elsewhere. During the 1930s, the Exakta VP was flanked on the market by just a few reflex cameras with larger format, such as the Primarflex and the Reflex Korelle, characterized by a 6x6cm square negative, not to mention the twin reflexes such as the Rolleiflex, Ikoflex and Superb, also with 6x6cm square format. Even if this competition made things difficult for the Exakta Vest Pocket, it should not be forgotten that, towards the end of the Thirties, lhagee heard the siren call of the 6x6cm format, offering a giant, 6x6cm format Exakta that competed with its own Exakta Vest Pocket.

However, with the close of the 1930s, it seemed that the Exakta Vest Pocket had exhausted all its potential while the life cycles of the single lens and 6x6cm twin-lens reflexes continued to develop after the war. The Rolleiflex and lkoflex survived, as did the Primaflex and Korelle, and even lhagee allowed itself to be seduced a second time by the 6x6cm format, presenting in the early 1950s an ill-fated 6x6 reflex named Exakta, but completely different from either the Exakta Vest Pocket or the pre-war 6x6 Exakta. In fact, after the war, Ihagee concentrated its efforts primarily on the Exakta 35mm while completely (and definitively) leaving aside the larger formats, above all the 4x6.5cm Vest Pocket format.

Original, imaginative and versatile, the Exakta Vest Pocket remained the symbol of a courageous and diversified approach to camera production, despite its relative lack of success. Thanks to the numerous and complex variations in its output, the Exakta Vest Pocket models have become splendid and much sought-after pieces for collectors.

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Copyright © 2012-2024 Evgenii Artemov. All rights reserved. Translation and/or reproduction of website materials in any form, including the Internet, is prohibited without the express written permission of the website owner.

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

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

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

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.

Diffraction

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

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

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.

Flare

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.

Ghosting

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.

Anastigmat

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.

Transmittance

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

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),

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 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.

Speed

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.

Weight

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.

Filters

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

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.