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Under low brightness, the shutter speed and ISO sensitivity can be flexibly selected.
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ISO sensitivity(Ayes O Kando, Iso Kando,ISO speed ) IsInternational Standards OrganizationFormulated by (ISO)Photographic filmIt is a standard of the above, and shows how weak a film can record.TraditionalSOSensitivity andDINIt is a summary of the sensitivities.
ISO sensitivity includes ISO100 / 21 °, ISO200 / 24 °, ISO400 / 27 °, ISO800 / 30 °, etc.With higher sensitivity,Shutter speedProper exposure can be obtained by increasing the speed by one step or reducing the aperture by one stop.For example, ISO1 / 1 ° has twice the ability to receive light as ISO200 / 24 °, so it is possible to record light with half the intensity of ISO100 / 21 °.
The higher the sensitivity, the higher the value and the higher the sensitivity, so it is faster for dark scenes and high-speed subjects.Shutter speedYou can shoot with.However, since the particles of the film are generally coarser, a low-sensitivity film is often used when image quality is required.
Film speed standard
Current ISO sensitivity standard
The current standard for ISO sensitivity is colorNegative filmFor ISO 5800: 1987 There is.Also, as a related standardMonochrome negative filmFor ISO 6: 1993 And colorReversal filmFor ISO 2240: 2003 There is.In these standardsarithmeticNotation (conventionalSOSensitivity) andLogarithmNotation (conventionalDINIt is stipulated to display both (sensitivity) .
Every time the film speed doubles, the arithmetic notation number doubles and the logarithmic notation number increases by 2 °.For example, a film with ISO 2/3 ° sensitivity is twice as sensitive to light as a film with ISO 200/24 °..
In many cases, the logarithmic notation is omitted, only the arithmetic notation is written, for example "ISO 100"..
Logarithmic notation SArithmetic notation of ° S To convert to
Using the formula, Round to the standard sensitivity of the closest value using the table in the next section.
Similarly, to convert arithmetic notation to logarithmic notation
To round to an integer using the formula.
Notation correspondence table
Notations of various film speeds are shown in the table below.However, each measurement method is different, so it is only a guide..
|Sv (APEX sensitivity value)||ISO arithmetic notation|
|Rice Shiner||German Shiner||Weston||General Electric||GOST (en)|
(Former Soviet Union, before 1987)
|Examples of film brands and camera products|
|1||6||9 °||5.5||First kodachrome|
|10||11 °||16||22||8||12||Kodachrome 8mm film|
|2||12||12 °||11||Gevacolor 8mm reversal film|
|16||13 °||11||Agfacolor 8mm reversal film|
|20||14 °||19||25||16||24||16||ADOX CMS20|
|3||25||15 °||22||Old Agfacolor, Kodachrome 25|
|32||16 °||21||27||24||40||22||Panatomic X|
|40||17 °||32||Kodachrome 40|
|4||50||18 °||23||29||40||64||45||Fuji RVP|
|64||19 °||45||Kodachrome 64, Ektachrome X|
|80||20 °||65||Ilford Commercial Ortho|
|5||100||21 °||26||32||80||125||90||Koda color gold, provia|
|125||22 °||90||Ilford FP4 +, Plus X|
|160||23 °||130||Fujicolor Pro 160C / S, High Speed Ektachrome|
|6||200||24 °||29||35||160||250||180||Fujicolor Superior 200|
|7||400||27 °||32||38||320||500||350||T Max, Tri X, Ilford HP5 +|
|640||29 °||560||Polaroid 600|
|1,000||31 °||700||P3200T Max, Ilford Delta 3200|
|9||1,600||33 °||1400-1440||Fujicolor 1600|
|12||12,500 (12,800)||42 °|
|20,000||44 °||Polaroid 612|
|13||25,000 (25,600)||45 °|
|14||50,000 (51,200)||48 °|
|15||100,000 (102,400)||51 °||Nikon D3s, Canon EOS-1D Mark IV|
|16||200,000 (204,800)||54 °||Canon EOS-1D X, Nikon D4, Pentax 645Z|
|17||400,000 (409,600)||57 °||Nikon D4s, Sony α ILCE-7S|
|18||800,000 (819,200)||60 °||Pentax KP|
|19||1,600,000 (1,638,400)||63 °|
|20||3,200,000 (3,276,800)||66 °|
|4,000,000||67 °||Canon ME20F-SH|
The ISO sensitivity of digital cameras is standardized by ISO 12232.In JapanCamera Imaging Equipment AssociationStandardization by (CIPA) is also being carried out. Digital cameraInCCD image sensorSuch asSolid-state image sensorThe sensitivity of is often expressed as ISO100 "equivalent".The ISO sensitivity of a digital camera is a guideline value for amplifying the signal on the image sensor.When amplifying the signalShot noiseNoise and thermal noise are also amplified, so if the ISO sensitivity is high, luminance noise and color noise will occur in the image.As with film, the higher the sensitivity, the faster it is in dark places.Shutter speedYou will be able to shoot with.Noise may be reduced by cooling the sensor.
Basically, it can be considered that the lower the sensitivity is set, the better the image quality is. However, depending on the characteristics of the image sensor, the image quality may deteriorate even if the sensitivity is too low (noise is reduced, but the highlight part is highlighted. (The overexposure and underexposure of the shadow area are likely to occur, and the color development and contrast become tight).for that reasonNikonIn digital single-lens reflex cameras, etc., the minimum sensitivity for regular use is set to 100 to 200, and below that, it is treated as desensitization when low-sensitivity shooting is absolutely necessary.Therefore, for digital photography, shooting at the recommended sensitivity (generally 100 to 200 moderate sensitivity) is considered to have the best image quality, and low-sensitivity shooting is when an open aperture or low-speed shutter is intentionally required for expression, or It is often limited to cases where a high-contrast expression is intentionally required.
- ^ "ISO 5800: 1987: Photography – Color negative films for still photography – Determination of ISO speed". 2009/4/4Browse.
- ^ "ISO 6: 1993: Photography – Black-and-white pictorial still camera negative film / process systems – Determination of ISO speed". 2009/4/4Browse.
- ^ "ISO 2240: 2003: Photography – Color reversal camera films – Determination of ISO speed". 2009/4/4Browse.
- ^ a b RE Jacobson, Sidney F. Ray, Geoffrey G. Attridge, and Norman R. Axford (2000). The manual of photography. Focal Press. P. 305–307. ISBN 9780240515748
- ^ Carson Graves (1996). The zone system for 35mm photographers. Focal Press. P. 124. ISBN 9780240802039
- ^ ISO 2721: 1982. Photography — Cameras — Automatic controls of exposure (paid download). Geneva: International Organization for Standardization.
- ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac "Classic camera special course No. 2, how to use the famous machine 105" p.75.
- ^ Digital camera sensitivity regulation
- "Classic camera special course No. 2, how to use the famous machine 105" Asahi Sonorama
Shutter speed(Shutter speed,British: Shutter speed ) IsカメラbyPhoto Summarized videoAt the time ofshutterIs released,the filmorImage sensor lensThroughLightExposed to (ExposedTime (exposure time, shutter speed, also abbreviated as "SS").The shorter this timeShutter speed is fast, The longerShutter speed is slowThat is. (To be precise, the expression speed is not appropriate. See notes) 
Shutter speedISO sensitivity,ApertureAlongsideExposedIt is one of the three major factors that determine.Also, if the shutter speed is slowCamera shake,Subject blurcause.The shutter speed can also be adjusted appropriately to enable a variety of photographic expressions.
Shutter speed series
In the series of shutter speedsMultiple seriesとContinental seriesExists.Currently, the intermediate shutter speed is added to the multiple series in 0.5EV increments and 0.3EV increments.Exposure compensationThere are many that correspond to.
Shutter speed and exposure
Of a certain subjectProper exposureIs ISO sensitivity,Aperture, Realized by the proper combination of shutter speeds.If the shutter speed is faster than the one corresponding to the proper exposure (short exposure time), it will be underexposed, and if it is slow (long exposure time), it will be overexposed.
The relationship between the proper exposure and the shutter speed is as follows.
- Lens aperture value (F value) Is constant, and the film and image sensor感 度If is constantsubjectThe brighter the shutter speed, the faster the shutter speed to achieve proper exposure, and the darker the shutter speed, the slower the shutter speed.
- If the brightness and sensitivity of the subject are constant, the wider the aperture (smaller F-number), the faster the shutter speed for proper exposure, and the larger the aperture (larger F-number), the slower the shutter speed.This relationshipConflictIt is said that this relationship is broken due to exposure for a long time under film shooting.Irregular reciprocity'(It may be underexposed or the color balance may be lost.)Digital cameraWhen exposed for a long time, noise is generated for a long time, and processing is performed to remove it.
- If the brightness of the subject and the aperture value are constant, the higher the sensitivity, the faster the shutter speed for proper exposure, and the lower the sensitivity, the slower the shutter speed.However, in general, even with filmDigital cameraHowever, the higher the sensitivity, the coarser the image quality.
- ND (neutral density) filter,PL (polarizing) filterIf a filter with a dimming effect such as a C-PL (circularly polarized light) filter is attached to the lens, the shutter speed required for proper exposure will be slowed down.For this reason, it is appropriate to use an ND filter when the slow shutter is released in a bright place or when the shutter is too bright to release.The shutter speed can be adjusted by adjusting the aperture, but the depth of field may change.Light OfdiffractionbySmall aperture blurEtc. need to be taken into consideration.It should be noted that the PL filter changes the degree of dimming by rotating and produces special effects such as affecting reflection, so it is necessary to consider it when using it for this purpose.
AE(Auto exposure) The camera has modes such as shutter speed priority AE, aperture priority AE, and program AE.When shooting with the shutter speed controlledShutter speed priority AEIs convenient to use.According to the desired shutter speedApertureIs automatically determined, and you can shoot with the proper exposure.AlsoAperture priority AEWhen shooting with, if the amount of light is constant, open the aperture (F valueThe smaller the shutter speed, the faster the shutter speed, and the smaller the aperture (larger F value), the slower the shutter speed.Especially deepDepth of field(Pan focus), The shutter speed will be slower, which may cause blurring.
The slower the shutter speed (longer exposure time), the more likely it is that the photo will be blurred.Also,lens OfFocal lengthIs long (TelephotoThe more), the more noticeable the blur is.There are camera shake, camera shake and subject shake in blur.
Camera shakeIs a blur caused by the shaking of the hand holding the camera when shooting with a handheld camera, and can be considered as a type of camera shake.
However, even if you stand a tripod or the like so that camera shake does not occur.ReflexWith a mirrorshutterIt may be caused by the impact of the tripod, the movement of the tripod, etc.Camera shakeThat.
Subject blur(Motion blur) Is a blur caused by the movement of the subject while the shutter is open.The feature of camera shake and camera shake is that the entire screen is shaken, while subject shake is a feature that only a moving subject is shaken. (Refer to the photo) As a guide, it is said that walking people do not shake for about 1/125 seconds or less, and sports shooting such as athletic meet does not shake for about 1/500 or less.
Camera shake is generally35 mm filmIt is said that this can be prevented by releasing the shutter for less than 1 second of the focal length in terms of conversion (for example, equivalent to 50 mm).Draw cornerIt is said that if the lens has a shutter speed of 1/50 second, and if the lens is equivalent to 100 mm, the shutter speed is 1/100 second or more.At shutter speeds lower than thattripod,MonopodIt can be solved to some extent by using such as, and recentlyDigital camera,interchangeable lensInsideImage stabilization mechanismHas been introduced, and some can be taken by hand even with a fairly low-speed shutter.However, even with these methods, camera shake and subject shake cannot be prevented.To prevent camera shakeRemote releaseTo use,rigidityChoose a tripod with a high height, stand it vertically and open the three legs firmly,WeightHanging something like,Mirror lockupThere are methods such as separating the exposure and the movement of the mirror.
To prevent blurring of the subject,ISO sensitivityRaise, open the aperture, orstrobeな ど照明There is no choice but to shorten the exposure time by a method such as using.in particularLandscape photographyThen, under low sensitivity with good image qualityPan focusAs a result of narrowing down the shutter speed, the shutter speed often slows down, and it is necessary to pay attention to subject blurring due to wind, such as waiting for the wind to stop before releasing the shutter.
To shoot while ensuring a constant shutter speedShutter priority AEHowever, in the case of a dark subject, the aperture may open and the depth of field may become too shallow.Therefore, there is also a means to achieve both depth of field and shutter speed by increasing the ISO sensitivity.However, it should be kept in mind that increasing the sensitivity causes noise. (See below)
For some modern digital cameras, a constant shutter speed is determined to prevent blurring, and at the same time a constant F-number is determined to ensure depth of field, which is automatically appropriate.ISO sensitivityMode in which the camera selectsTAv modeEtc.) are appearing.
Changes in image quality depending on shutter speed
I would like to compare how the image looks different depending on the shutter speed, using the same subject taken with a high-speed shutter and a low-speed shutter.
These are pictures of the same stream of water.In the photo on the left, a moment of water is captured as if it were frozen, while on the right, the water is represented as a bundle of white threads due to slight blurring of the subject, and is captured as a flow.
In this way, when you want to keep the subject still, use the high-speed shutter to shake (Motion blurWhen trying to incorporate the element of), it is effective to adjust the shutter speed to a slower speed.In addition, when using a low-speed shutter by incorporating the element of subject blur into the expression, in order to prevent camera shake and camera shake,tripodとReleaseThe use of is mandatory.
Expression by high-speed shutter
A fast shutter speed is required to shoot a fast-moving object (racing car, airplane, etc.) at rest (stop blurring of the subject).Sample 1Then, in 1/125 seconds, the milk bounces,Sample 2Then, the figure of a racing car running at high speed with a high-speed shutter of 1/2000 seconds is captured.
Expression by low-speed shutter
For example,Air showEtc.Propeller planeThis is adopted because if you stop it with a high-speed shutter, the feeling of dynamism will be impaired.But aside from the propeller plane,helicopterThen.rotorWhen I try to rotate, this timeAircraftIt is said that it is difficult to shoot because the probability of blurring increases.
Sample 3Is also a picture of a racing car, and unlike example 2, the background is flowing.This was taken using a low-speed shutter while moving the direction of the camera according to the movement of the racing car. "PanningIt is a shooting method that requires a little advanced technique, and it expresses a strong sense of speed.
Sample 4Is taken by moving the zoom ring of the zoom lens during the exposure time with a low-speed shutter.Zoom between exposuresThis is a technique called.
Expression by long exposure
Night viewAndfireworks,AstrophotographyIn the shooting oftripodStand up,,timeVarious expressions are made by performing long exposure (generally referring to a shutter speed of 1 second or longer) by opening the shutter in a shooting mode such as.
In astronomical photographyEquatorialBy using a special gantry called, the camera is tracked by the movement of celestial bodies and exposed for a very long time, very dark stars that are invisible to the naked eye and星雲,Star clusterEtc. are also copied.Sample 5Is an astrophotography with a long exposure of 35 minutes.paleGalaxyIs clearly projected.
Sample 6 TheNara-Todaiji TempleNigatsu-do"Otamatsu". 8 secondsvalveRelease the shutter and swing aroundTorches OfTueThe light trails of the are dynamically expressed as if they wrap around the entire hall.
In this way, various photographic expressions are possible by adjusting the shutter speed.
However, it is necessary to keep in mind that there is a harmful effect that noise of the image sensor is generated as a phenomenon peculiar to the digital still camera.There are various factors such as when the ISO sensitivity is excessively increased, when the exposure time is lengthened, or when the surrounding exposure cannot be obtained.In some cases, it may appear as a weakness of the specific camera itself.
Sample 8Is an attempt to shoot with a weak light source in a very low exposure environment, but digital noise due to low exposure is conspicuous.This is due to the unique characteristics of this camera, which is very difficult to prevent in this case.
Sample 8TritiumWatch using.About 9 seconds
- ^ Since speed is originally a physical quantity (unit: m / sec) that indicates the distance traveled per unit time, it is not appropriate to use the word speed to describe the exposure time (unit: sec) (shutter is configured). The speed at which the leading and trailing curtains move is constant, and the exposure time is determined by the time difference between the two running starts).Therefore, although it has become an established fact as a term, it is possible to think that it should be expressed as "shutter time" or "exposure time".
- ^ Osamu Takeishi (May 2012, 5). “Special Edition: Asking the Pan Head Maker How to Choose and Use a "Blur-Free" Tripod". Digital camera Watch Digital camera item bowl. 2020/2/22Browse.