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Canonflex

35mm MF film SLR camera

Specification

Production details:
Announced:May 1959
System:● Canon R (1959)
Format:
Maximum format:35mm full frame
Film type:135 cartridge-loaded film
Mount and Flange focal distance:Canon R [42mm]
Shutter:
Type:Focal-plane
Model:Mechanical
Speeds:1 - 1/1000 + B
Exposure:
Exposure metering:None
Exposure modes:Manual
Physical characteristics:
Weight:940g
Dimensions:145x100x49mm

Manufacturer description #1

The unprecedented CANONFLEX is the highest achievement in the 20-year history of Canon. Behind it are the unique experience and skill of Canon's unsurpassed design, engineering, and construction staffs.

The Canonflex is made for the professional, as well as the discerning amateur - for all photographers who want to record a picture with the same clarity and ease as the naked eye. After you release the shutter, the automatic lens diaphragm springs back to full aperture and the automatic mirror springs back to open position to disclose with full brightness the scene you have just photographed. In addition to this Canon-exclusive feature, the Canonflex is the only single-lens reflex camera in the world with the detachable exposure meter (Canon-Meter R) coupled to the speed dial automatic, dual strobo-flash synchronization socket anti-film curl roller trigger-action lever These, and many other, superb features of the Canonflex are proof positive that it is the world's foremost single-lens reflex camera.

The eye-level ease with which the Canonflex is used may be summed up in the words "quick-as-a-wink." Fast trigger-action lever! Even in the most difficult situations, you can rely on the Canonflex to give you the picture you want.

The new Super-Canomatic Lens R has the unexcelled quality of all Canon lenses, and guarantees pictures of the utmost clearness and critical sharpness. When you release the shutter, the diaphragm closes automatically to the pre-selected aperture stop then reopens automatically to full aperture immediately after exposure. No parallax problems ever with the Super-Canomatic Lens R or any of the many interchangeable lenses that can be used, as the object is always viewed through the taking lens.

Canon-Exclusive Super-Canonmatic Lens R 50mm f:1.8 (with Automatic Springback Diaphragm) Fully Synchronized with Automatic Spring back Mirror

Canon-exclusive, springback mirror, fully synchronized with the Super-Canomatic Lens R, is actuated by the shutter. As the shutter is released, the mirror flips up and returns automatically to the original position immediately after exposure. This action enables you to view the scene continuously. No "blackouts" with the new Canonfiex.

The Canon-exclusive, Super-Canomatic Lens R (with automatic springback diaphragm mechanism) is pre-set to a desired diaphragm opening. You can view and focus at full aperture (full brightness). As the shutter is released, the diaphragm closes to the pre-selected aperture stop, and then automatically reopens to full aperture immediately after exposure. This feature is a "must" for picture taking under poor light conditions.

In order to see the depth of field, when needed, the visual aperture ring can be operated manually to disclose the exact depth of field of the pre-selected aperture. This is impossible with the rangefinder-type camera. It is important, however, to set the visual aperture ring back to full opening before the shutter is released.

Canonflex, Split-Image Type Range-Viewfinder

The Canon-exclusive. Echelette (patented) split-image type range- viewfinder, the brightest of any on today's market, is incorporated into the Canonflex single-lens reflex system. A double concentric makes it doubly simple to match the range- finder lines for extreme accuracy.

For convenient focusing, the frosted surface of the rangefinder can be used. For more critical focusing, the split-image rangefinder lines should be used. As soon as the split-image appears in perfect alignment, the lens is critically focused.

Canon-Exclusive, Eye-Level Pentaprism, Interchangeable with Waist-Level Viewer

For ease in picture taking, viewing and focusing is done normally with the eye-level pentaprism viewfinder. The eye-level pentaprism is interchangeable with the accessory waist-level viewer (4 X magnification). You can choose either viewfinder depending on your need.

Thru-the-lens focusing of the single-lens reflex system eliminates all the problems of parallax usually associated with twin-lens reflex or rangefinder-type cameras. You are absolutely free of parallax at all time with any lens used. What you see through the viewing and focusing eyepiece is what you record on film. You get edge-to-edge, naked-eye-clear-and-sharp pictures every time! No cutting off heads or feet!

Canon-Exclusive, Motor-Speed Trigger-Action Lever

A single-stroke of the Canonflex trigger-action lever advances the film, cocks the shutter, counts exposures in one operation. Simultaneously, it readies the springback diaphragm and mirror for picture taking.

You can take as many as 3 pictures per second! The lever cannot be wound unless the shutter is released.

Canonflex, Detachable, Canon-Meter R Coupled to the Shutter Speed Dial

The Canon-Meter R is coupled to the shutter speed dial of the Canonflex. It is attached to the accessory clip on the front of the camera body and can be detached for use separately. Canon-Meter R has the highest sensitivity in spite of its small size. The sensitivity knob has white and orange marks. The white mark is for an object in bright light (when low sensitivity is needed). The orange mark is for an object in poor light condition (when high sensitivity is needed). The Canon-Meter R has such a high sensitivity that it will work for an object having light value as low as 4 (LV 4). This means that the meter will work even in poor light condition where you have to use 1/4 sec. with an f 1.2 or 1/2 sec. with an f 1.8 using ASA 100 film. No other light-meter among similar types can match Canon unless combined with attachment. Using ASA 100 film the sensitivity range of Canon-Meter R is

Low Sensitivity Range - Light Value - 10-19 lumen

High Sensitivity Range - Light Value - 4-13 lumen.

When the meter indicator is turned to match the pre-set aperture reading the shutter is automatically set to the correct exposure time. Conversely if the shutter speed is first set, the correct lens aperture will automatically be determined. The Exposure Indicator Dial is calibrated in both ASA and DIN. An incident light attachment is provided with the Canon-Meter R.

Easy-to-Read, Film-Type Reminders

The film-type reminder of the Canonflex surrounds the film rewind crank, which is on the top (left side) of the camera.

ASA and DIN indicators constantly remind you of the speed changes. Three marks are also incorporated on the film-type reminder disc to show the type of film with which the camera is loaded; black and white, daylight- type color, or tungsten-type color.

The film-type reminder is set manually with selector rings, which are revealed when the rewind crank is lifted up.

Canonflex, Automatic Exposure Counter

The film exposure counter which indicates the number of exposures, returns automatically to "s" (starting) position whenever the back cover of the camera is opened. One frame is advanced as the shutter is cocked. Numbering starts from zero.

Canonflex, Single-Pivot, Rigid Shutter Speed Dial

The shutter speed dial, with its equal, linear spacing, and click stops, is on a single pivot, with 11 speeds ranging from 1 second to 1/1000th of a second plus B (bulb)-T and X for strobo-flash synchronization. T (Time) exposure does not require resting your finger on the shutter release button for any length of time. Simply shift the time lever! The shutter will stay open until the time lever is returned to its original position.

Canonflex Built-in Self-Timer

Built-in self-timer of the Canonflex, which allows you to get in the picture, is the shutter button type. Canon's unique shutter-release button system eliminates confusion between ordinary and time exposures. Cable release hole is provided. Maximum delay of self-timer is 10 seconds.

Canon-Exclusive, Cordless, Automatic, Single-flash Socket for Dual Strobo and Flash Synchronization

Either BC flash unit, or electronic flash unit, is fitted directly to the single, bayonet-fitting socket on the camera. The circuit is automatically connected as the unit is attached eliminating the use of exterior wiring. Use the specially fitted cam flash gun or any other standard flash gun. Extensions can be used, if desired.

The setting of the shutter speed dial automatically sets the synchro-mechanism with the shutter mechanism for accurate flash timing (adjustment of type M and FP bulbs). The new Canonflex can be used with any kind of flash bulb, or electronic flash, without any further setting or adjustment. X-1/60sec. FP 1-1/1000sec. M 1-1/250sec. F 1/35sec.

Canon-Exclusive, Anti-Film Curl Roller and Self-Loading Cassettes

Canon-exclusive, anti-film curl roller on the pressure plate prevents warping and curling of film, which assures critical and accurate focusing at full aperture of the highest speed lenses, where the depth of field is extremely shallow.

The new Canonflex takes either standard or Canon film cassettes (Canon Film Magazine V).

Interchangeable Lenses for The Canonflex

Canon lenses are held in the highest esteem by professional and discerning amateur photographers the world over for their unsurpassed, unique optical design, exclusive Spectra-Coating (TM), and precision engineering.

Canon pioneered development of high-speed lenses opening new field of photographic versatility to the serious photographer.

The unmatched interchangeable Super Canomatic lenses are designed and made to the same exacting quality standards as the famed Canon 35mm rangefinder-type camera lenses.

Before leaving the factory, all Canon lenses must meet rigid tests to insure the highest resolution, contrast, brilliance, and color fidelity in addition to the new- response-function testing method.

The Super Canomatic lenses have fully-automatic springback diaphragm. The front part of the Super-Canomatic Lens R serves as the sun shade eliminating the use of extra attachment. All Canon lenses, 85mm or longer focal length, can be used with the Canonflex, in combination with focusing adapter tele-coupler or tele-coupler and bellows focusing device, depending upon the focal length and the type of lens used. With focusing adapter, Canon screw-mount interchangeable lenses from 85mm to 135mm can be used with the versatile Canonflex. With Canon's tele-coupler R, and bellows focusing device their unique, lightweight, aluminum telephoto lenses from 200mm to 1000mm can be used with the new Canonflex.

Manufacturer description #2

The top-class 35mm camera market gradually shifted from rangefinder cameras to single-lens reflex cameras. The major reason was that SLRs could handle close-ups, photomicrography, duplication work, and other applications without being constrained by the limits of rangefinder camera lenses. When Canon introduced the Canonflex, its first SLR, there were already eight SLR models on the market.

The Canonflex used a high-quality, breechlock lens mount. The lens flange ring was turned to lock the lens onto the camera flange’s bayonet lugs. The lens flange and camera flange did not rub against each other like today’s lens mounts. The camera used Super-Canomatic lenses which had a fast, fully-automatic diaphragm. A 130-degree winding trigger at the camera bottom enabled quick film advance. An external selenium exposure meter could also be attached.

From the Classic Camera magazine (May 1999)

The Canonflex is a chunky and tough camera, designed and built with care and attention to detail and using many leading edge technical solutions, some of which, however, proved to be quite unpractical. The Canonflex had a horizontally running cloth shutter and a top speed of 1/1000s. It was designed to accept a clip on light meter and had an instant mirror return mechanism. The pentaprism was interchangeable, but the focusing screen was fixed and could not be replaced with other screens. In place of the traditional film wind lever, the Canonflex had a folding lever placed in the base plate, and the self timer lever at the front was replaced by a removable key.

Lenses were interchangeable, with an external bayonet mount and a locking ring placed on the lens barrel, but the automatic aperture control was achieved through two different mechanisms, one to close and one to open the iris. The fact that viewfinders were interchangeable was in fact purely theoretical, since the only alternative was a so-called rigid viewfinder which was useful for copies, but little else.

The external light meter was coupled to the shutter but not the aperture control, and this represented a small handicap which compounded that of the film wind lever on the base plate. The Canonflex camera body was square cut, similar in appearance to the Canon V and VI and to the successive Canon 7.

The mirror box was also square and the front, apart from the self timer key socket and the light meter bracket, was clean.

The pentaprism was solid, square cut and black. To the right of the top plate was a large black shutter speed selector knob, characterised by its knurled finish, devised to engage a gear in the coupled light meter. Next to the shutter speed control were the shutter release and the frame counter window.

On the opposite side, the film rewind lever crank was set into a film memo ring. The camera back was hinged to the side and was opened by means of a key in the base plate, while the synch socket was placed on the left hand side as in the rangefinder Canon.

The result of expert and careful design mutuated from the rangefinder cameras, the Canonflex displayed a few naive touches and was never the commercial success it deserved to be, also due to an inadequate marketing campaign.

The Canonflex remained in production for one year, from May 1959 to May 1960 and was made in 16,000 examples.

The commercial success of the Canon VI-L and the Canon P with the top plate positioned film advance lever, suggested nothing to Canonflex's designers, who offered the not so successful base plate mounted lever in the SLR, persevering even in the next two models, while the rangefinder models definitively abandoned this system with the Canon 7.

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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

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, Nikon, Pentax, Sony etc.) are always incompatible. In addition to the mechanical and electrical interface variations, the flange focal distance can also be different.

The flange focal distance (FFD) is the distance from the mechanical rear end surface of the lens mount to the focal plane.

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 and/or rear lens elements 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.