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| {{refimprove | date=September 2009}}
| | == 「行ってみたい == |
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| [[Image:Macrogl Stellat.jpg|thumb|right|The furious wing action of a [[Macroglossum stellatarum|hummingbird hawk-moth]] is frozen by flash. The flash has given the foreground more illumination than the background. See [[Inverse-square law]].]] | | 炎症？ ！ '<br><br>直接魂、体と呼ばれる宿敵の魂を燃やすことができる心臓の炎症秋、それは目に見えない炎、手数料日間のアバターが突然叫んだ、彼の目は恐怖、Baotuiの身長のヒントをフラッシュし、彼の知識と、自然に知っているを参照してください。 [http://www.ispsc.edu.ph/nav/japandi/casio-rakuten-2.html 腕時計 casio] 。<br><br>「行ってみたい？ '<br>これを見<br>は、シャオヤン魂力Skyfireの法王で、彼の強さは、手数料日間のアバターよりも弱いされている、冷笑され、激しく、様指紋が変更され、火が激しいpythonの速度をジャンプし、最終的にサンダーなどコスト日間の体への影響 [http://www.ispsc.edu.ph/nav/japandi/casio-rakuten-2.html カシオ腕時計 g-shock]。<br><br>「強打！ [http://www.ispsc.edu.ph/nav/japandi/casio-rakuten-14.html casio 腕時計 phys] '<br><br>はそれPutui、目に見えない火のpythonを聞かせていない、火災パイソン、Leiguang上記料金日間のアバターが突然包ま体が消えたヒットだけでなく、再び深刻にヒット従います [http://www.ispsc.edu.ph/nav/japandi/casio-rakuten-6.html 腕時計 メンズ casio]。<br>「ああ [http://www.ispsc.edu.ph/nav/japandi/casio-rakuten-13.html カシオ腕時計 メンズ]！」<br><br>失われたLeiguangボディケア<br>、コスト日間のアバターが突然衝突された心臓の炎症の秋、瞬間が発行する |
| | 相关的主题文章： |
| | <ul> |
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| | <li>[http://zqno1.com/bbs/forum.php?mod=viewthread&tid=59260&extra= http://zqno1.com/bbs/forum.php?mod=viewthread&tid=59260&extra=]</li> |
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| | <li>[http://sctjsb.com/plus/feedback.php?aid=18 http://sctjsb.com/plus/feedback.php?aid=18]</li> |
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| | <li>[http://www.7cost.com/forum.php?mod=viewthread&tid=1438573 http://www.7cost.com/forum.php?mod=viewthread&tid=1438573]</li> |
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| | </ul> |
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| A '''flash''' is a device used in [[photography]] producing a flash of [[Lighting|artificial light]] (typically 1/1000 to 1/200 of a second) at a [[color temperature]] of about 5500 K to help illuminate a scene. A major purpose of a flash is to illuminate a dark scene. Other uses are capturing quickly moving objects or changing the quality of light. ''Flash'' refers either to the flash of light itself or to the '''electronic flash unit''' discharging the light. Most current flash units are electronic, having evolved from single-use flashbulbs and flammable powders. Modern [[camera]]s often activate flash units automatically.
| | == 薬「何をしたいあなたの谷Guzhu精錬とは == |
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| Flash units are commonly built directly into a camera. Some cameras allow separate flash units to be mounted via a standardized "accessory mount" bracket (a ''[[hot shoe]]''). In professional studio equipment, flashes may be large, standalone units, or ''studio strobes'', powered by special battery packs or connected to [[mains power]]. They are either synchronized with the camera using a [[flash synchronization]] cable or radio signal, or are light-triggered, meaning that only one flash unit needs to be synchronized with the camera, and in turn triggers the other units, called ''slaves''.
| | ささやくこれらの人々のために、シャオヤン数分スキミングなどのタイトな赤い火長老で、聞いたことがないが、次第に名声を低下させ、前に赤いホールを上陸させた [http://www.ispsc.edu.ph/nav/japandi/casio-rakuten-13.html カシオ アナログ 腕時計]。<br><br>谷腹、赤Fenyanバレーシャトルに身を包んだ弟子たちがたくさんある建物の多くは、時折それがこの巨大な谷の出現は、より活力を約束したので盛は、鳴っ学ぶ。<br>多くの焚炎バレーの弟子ガードと現時点で<br>外側の赤いホールは、警察の目は絶えず周り総なめにした。<br><br>防衛」にも教祖 [http://www.ispsc.edu.ph/nav/japandi/casio-rakuten-13.html casio 腕時計 edifice] '薬'それはいくつかの他の精錬ようだが、「保護された会場を見て、赤い火長老たちがつぶやいた。<br><br>薬「何をしたいあなたの谷Guzhu精錬とは [http://www.ispsc.edu.ph/nav/japandi/casio-rakuten-3.html 電波時計 カシオ]？実際にそんなに精錬が必要」「先生 [http://www.ispsc.edu.ph/nav/japandi/casio-rakuten-0.html casio 腕時計]？「わずかにしわが寄っシャオヤンの眉、と述べた。<br>探し、医学 [http://www.ispsc.edu.ph/nav/japandi/casio-rakuten-4.html casio 腕時計 g-shock] '分裂'ああ、あなたがこれらの精錬から欲しいそんなに必要なのではなく、「<br> |
| | 相关的主题文章： |
| | <ul> |
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| | <li>[http://www.hanindus.com/plus/feedback.php?aid=31 http://www.hanindus.com/plus/feedback.php?aid=31]</li> |
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| | <li>[http://2rkj.tk/plus/view.php?aid=1790 http://2rkj.tk/plus/view.php?aid=1790]</li> |
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| | </ul> |
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| ==Types of flash== | | == 「その後、知り合いに == |
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| ===Flash-lamp=== | | その後暁の少し再帰カラースケールのリードを手に入れた頭部、および、第1の色スケールを定住娘に言った。<br><br>「その後、知り合いに。 '<br>また、人と考えるhuanhangrn透明色スケールは、メンタリングが言うことを何かを持っていることを知って、シャオヤンの前の瞬間は、シャオシャオがゆっくりと後退さ取った後、そっと何かを言った [http://www.ispsc.edu.ph/nav/japandi/casio-rakuten-9.html カシオ 掛け時計]。<br>Xiaoxiaoは、ちょうどゆっくり古い目を回復する、 [http://www.ispsc.edu.ph/nav/japandi/casio-rakuten-12.html 腕時計 メンズ casio] '薬'をカラースケールを後退微笑んで言って<br>は先に見えた： [http://www.ispsc.edu.ph/nav/japandi/casio-rakuten-4.html カシオ 腕時計 バンド] '少年は、これは実際に良い娘を出産していますが、実際にはメドゥーサと行くでしょう本当に私を驚かせたにしています。 [http://www.ispsc.edu.ph/nav/japandi/casio-rakuten-5.html 時計 casio] '<br><br>シャオヤンは、彼とカラースケールは確かに複雑すぎるとの関係をあなたの手を投げた、誰もが、数年後を追いかける女王メデューサ、そして最後に、実際に彼の妻であるシャオヤンを殺すために、今年、想像できない [http://www.ispsc.edu.ph/nav/japandi/casio-rakuten-7.html casio 腕時計 説明書]。<br><br>'あなたはこの事は、私は聞いたことが、2リビアの過去、家の魂と十分なQiaochuを送ることができます |
| {{main|Flash-lamp}}
| | 相关的主题文章： |
| | <ul> |
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| | <li>[http://ylrzdb.com/plus/feedback.php?aid=38 http://ylrzdb.com/plus/feedback.php?aid=38]</li> |
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| | <li>[http://www.qiaoclub.com/plus/feedback.php?aid=17 http://www.qiaoclub.com/plus/feedback.php?aid=17]</li> |
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| [[File:1909 Victor Flash Lamp.jpg|thumb|upright|1909 flash-lamp <br /> 1903 view camera]]
| | == 第千三百二十章第九のエネルギー体 == |
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| The earliest flashes had a quantity of [[flash powder]] consisting of a mechanical mixture of [[magnesium]] powder and [[potassium chlorate]] that was ignited by hand. The first such flash-lamp was invented by [[Joshua Lionel Cowen]] in 1899. His patent describes a device for igniting photographers’ flash powder by using dry cell batteries to heat a wire fuse. Within a few years, other types of lamp were being employed. In some, an electric circuit triggered a fuse to ignite explosive powder (such as [[magnesium]]). By 1905, non-explosive electric lamps were being used, such as when a French photographer employed [[carbon arc lamp]]s.<ref name="PopMech1905v7n2p233">{{Cite journal |date=February 1905 |title=Taking instantaneous photographs by electric light |journal=Popular Mechanics |volume=7 |issue=2 |page=233 |url=http://books.google.com/books?id=Wd4DAAAAMBAJ&pg=PA233#v=onepage&f=false}}</ref>
| | 彼は今薫の子供たちのためにこれらの核エネルギーを知っていたものの吸収は、薫の子供たちはほんの少しの参加、効果はあまり大きくないが、彼はまた、それが子供たちが意図的に彼を与える口実を探して喫煙されることを認識している [http://www.ispsc.edu.ph/nav/japandi/casio-rakuten-2.html カシオの時計]。<br>薫の子供たちはささやいた、微笑ん<br>：「5日間の時間がありますが、私たちは第三層に到達することができるはずであり、シャオシャオ玄ファミリーの祖先の墓ハウス、それがどこにあるべき」<br><br>ウェンヤンは、シャオヤンがゆっくりと首を縦に振ったが、希望の私の心の不可解なタッチで、私はなぜ知らない、彼は常にシャオ府中市神秘的な墓は、後に彼に遺贈の祖先を持って確実であることを予感を持ってい物事の人々の一部<br><br>第千三百二十章第九のエネルギー体<br><br>第千三百二十章第九のエネルギー体<br>最終的には地球上の<br>広大な孤独、浸透の安定した流れうち地上霧からの豊富なエネルギー、土地のこの作品の最後に姿を包ま |
| | | 相关的主题文章： |
| ===Flashbulbs===
| | <ul> |
| [[File:Brownie Hawkeye with Flash.jpg|thumb|right|Kodak Brownie Hawkeye with "Kodalite Flasholder" and Sylvania P25 blue-dot daylight-type flashbulb]]
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| | | <li>[http://www.shayou.net/news/?action-viewcomment-type-zhongyi-itemid-1717 http://www.shayou.net/news/?action-viewcomment-type-zhongyi-itemid-1717]</li> |
| The use of flash powder in an open lamp was replaced by ''flash bulbs''; magnesium filaments were contained in bulbs filled with [[oxygen]] gas, and electrically ignited by a contact in the [[camera]] [[Shutter (photography)|shutter]]. Such a bulb could only be used once, and was too hot to handle immediately after use, but the confinement of what would otherwise have amounted to a small explosion was an important advance. A later innovation was the coating of flashbulbs with a plastic film to shield the bulb in the unlikely event of its shattering during the flash. A blue plastic film was introduced as an option to match the spectral quality of the flash to daylight-balanced colour film. Later bulbs substituted [[zirconium]] for the magnesium, which produced a brighter flash but tended to temporarily blind people.
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| | | <li>[http://www.securitygoeasy.com/plus/feedback.php?aid=37 http://www.securitygoeasy.com/plus/feedback.php?aid=37]</li> |
| Flashbulbs took longer to reach full brightness and burned for longer than electronic flashes. Slower shutter speeds (typically from 1/10 to 1/50 of a second) were used on cameras to ensure proper synchronization. Cameras with [[Flash_synchronization#M.2C_F.2C_FP.2C_X_and_HSS_sync|flash synch]] triggered the flashbulb a fraction of a second before opening the shutter, allowing faster shutter speeds. A flashbulb widely used during the 1960s was the Press 25, the (about 1 inch (25 mm) in diameter) flashbulb often used by newspapermen in period movies, usually attached to a [[press camera]] or a [[twin-lens reflex camera]]. Its peak light output was around a million lumens. Other flashbulbs in common use were the M-series, M-2, M-3 etc., which had a small ("miniature") metal [[bayonet mount|bayonet base]] fused to the glass bulb.
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| | | <li>[http://www.tricolore.net/cgi-bin/personal/italians.cgi http://www.tricolore.net/cgi-bin/personal/italians.cgi]</li> |
| The all-glass AG-1 bulb was introduced in 1958. Eliminating both the metal base, and the multiple manufacturing steps needed to attach it to the glass bulb, cut the cost substantially compared to the larger M series bulbs. The AG-1 (along with the M2) had a faster ignition time (less delay between shutter contact and peak output), so it could be used with X synch below 1/30 of a second—while most bulbs require a shutter speed of 1/15 on X synch to keep the shutter open long enough for the bulb to ignite and burn.<ref>[http://photo.net/classic-cameras-forum/00CYlj "AG-1 Flashbulb History"]. Photo.net. Retrieved 5 July 2013.</ref>
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| | | </ul> |
| <!--*** FOLLOWING "SPAN" SECTIONS ARE FOR REDIRECTS TO THIS ARTICLE SECTION WHICH WON'T BREAK IF THE SECTION'S TITLE IS CHANGED ***--> | |
| <span id="flashcube"></span><span id="magicube"></span><span id="flipflash"></span> | |
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| ====Flashcubes, Magicubes and Flipflash<!--This section is linked from [[GTE]]-->====
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| [[Image:Flashcube on Kodak Instamatic.jpg|thumb|175px|right|Flashcube fitted to a Kodak Instamatic camera, showing both unused (left) and used (right) bulbs]]
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| [[Image:Magicube-Modified.jpg|thumb|175px|right|Undersides of Flashcube (left) and Magicube (right) cartridges]]
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| [[Image:Flip Flash.jpg|thumb|175px|"Flip flash" type cartridge]]
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| In the late 1960s [[Kodak]] improved their [[Instamatic]] camera line by replacing the individual flashbulb technology (used on early Instamatics) with the ''Flashcube''. A flashcube was a single-use module with four flashbulbs mounted at 90° from the others in its own reflector. For use it was mounted on a swivel mechanism atop the camera that also provided an electrical connection to the shutter release and a battery inside the camera. After each exposure, the film advance mechanism also rotated the flashcube 90° to a fresh bulb. This arrangement allowed the user to take four images in rapid succession before inserting a new flashcube.
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| The later Magicube (or X-Cube) retained the four-bulb format, and was superficially similar to the original Flashcube. However, the Magicube did not require electrical power. Each bulb was set off by a plastic pin in the cube mount that released a cocked spring wire within the cube. This wire struck a primer tube at the base of the bulb, which contained a [[fulminate]], which in turn ignited shredded [[zirconium]] foil in the flash. Magicubes could also be fired by inserting a thin object, such as a key or paper clip, into one of the slots in the bottom of the cube.
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| Flashcubes and Magicubes look similar but are not interchangeable. Cameras requiring flashcubes have a round socket and a round hole for the flashcube's pin, while those requiring Magicubes have a round shape with protruding studs and a square socket hole for the Magicube's square pin. The Magicube socket can also be seen as an X, which accounts for its alternate name, the X-Cube.
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| Other common flashbulb-based devices were the Flashbar and Flipflash which provided about ten flashes from a single unit. The Flipflash name derived from the fact that once half the flashes had been used up, the unit was flipped over and re-inserted to use the remainder.
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| ===Electronic flash===
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| Electronic flash was developed after flashbulbs, and eventually superseded them as prices came down; flashbulbs are virtually obsolete. A typical electronic flash unit has [[electronic circuit]]ry to charge a high-capacity [[capacitor]] to several hundred [[volt]]s. When the flash is triggered by the shutter's flash synchronization contact, the capacitor is discharged almost instantaneously through a [[flash tube]], producing a flash of very brief duration almost instantaneously (i.e., the flash duration, often around 1/1000 of a second, is no longer than the fastest practical shutter speed, and full brightness is reached before the shutter has time to close appreciably). [[Flash synchronization|Synchronization]] of full flash brightness with maximum shutter opening was problematical with bulbs which took an appreciable time to ignite and reach full brightness; electronic flash does not have these difficulties. Electronic flash units are sometimes called ''speedlights'' or ''strobes'' in the USA.
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| Simple electronic flash units are often mounted on or near the camera; many inexpensive [[camera]]s have an electronic flash unit built in.
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| [[Image:Flash - Speedlight - SLR Flash - Studio picture 2011.jpg|thumb|right|Two professional xenon tube flashes]]
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| [[File:Nikon Medical-Nikkor.png|thumb|left|Special macro lens with built-in ring flash light]]
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| Some lenses have built-in (ring-)flash lights for shadow free macro photography, but there are also accessory ring flashes available.
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| In a photographic studio more powerful and flexible studio flash systems are used. They usually contain a [[modeling light]], an [[incandescent light bulb]] close to the flash tube; the continuous illumination of the modeling light lets the photographer visualize the effect of the flash. A system may comprise multiple synchronised flashes for multi-source lighting.
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| The strength of a flash device is often indicated in terms of a [[guide number]] designed to simplify exposure setting. The energy released by larger studio flash units, such as [[monolight]]s, is indicated in [[watt-seconds]].
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| ===High speed flash===
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| An [[air-gap flash]] is a high-voltage device that discharges a flash of light with an exceptionally short duration, often much less than one [[microsecond]]. These are commonly used by scientists or engineers for examining extremely fast-moving objects or reactions, famous for producing images of [[bullet]]s tearing through light bulbs and balloons (see [[Harold Eugene Edgerton]]).
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| [[Image:Bullet coming from S&W.jpg|thumb|A photo of a [[Smith & Wesson Model 686]] firing, taken with a high speed [[air-gap flash]]. The photo was taken in a darkened room, with camera's shutter open and the flash was triggered by the sound of the shot using a microphone.]]
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| ===Multi-flash===
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| A camera that implements multiple flashes can be used to find depth edges or create stylized images. Such a camera has been developed by researchers at the [[Mitsubishi Electric Research Laboratories]] (MERL). Successive flashing of strategically placed flash mechanisms results in shadows along the depths of the scene. This information can be manipulated to suppress or enhance details or capture the intricate geometric features of a scene (even those hidden from the eye), to create a non-photorealistic image form. Such images could be useful in technical or medical imaging.<ref>{{cite web|last=Nicholls|first=Kyle|title=Non-photorealistic Camera|url=http://www.photo.net/learn/technology/mflash/merl-non-photo.html|publisher=Photo.net|accessdate=28 December 2011}}</ref>
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| ===Flash intensity===
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| Unlike flashbulbs, the intensity of an electronic flash can be adjusted on some units. Small flash units typically vary the length of time of the discharge, larger (studio) units typically charge the capacitor less. The disadvantage of charging the capacitor less is that the color temperature may change, necessitating corrections. With advances in semiconductor technology, there are some monolight (studio) units which can vary the time of the discharge.<ref>{{cite web |url=http://www.paulcbuff.com/sfe-flashduration.php |title=Studio Flash Explained: Flash Duration |publisher=Paul C. Buff, Inc |accessdate=5 July 2013}}</ref>
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| The flash duration is typically described with two numbers: t.5 is the length of time for which the flash impulse is above 0.5 (50%) of the peak intensity, while t.1 is the length of time for which the impulse is above 0.1 (10%) of the peak<ref>{{cite web |last=Cullen |first=Shawn |url=http://www.sportsshooter.com/news/1888 |title=Ask Sports Shooter: Understanding Flash Duration |publisher=Sports Shooter |date=17 December 2007}}</ref> (t.3 of course, would be above 30%). For instance, t.5 can be 1/1200 sec whereas t.1 can be 1/450 sec for the same flash at the same intensity. For a small flash controlling intensity by time, the t.5 and t.1 numbers decrease as the intensity decreases. On flash units controlling intensity by capacitor charge, the t.5 and t.1 numbers ''increase'' as the intensity decreases (i.e. takes longer for the capacitor to discharge to that point). These times become important if a person wants to freeze action with the flash (as in sports).
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| Flash intensity is typically measured in stops or in fractions (1, 1/2, 1/4, 1/8 etc.). Some monolights display an "EU Number", so that a photographer can know the difference in brightness between different flash units with different watt-second ratings. EU10.0 is defined as 6400 watt-seconds, and EU9.0 is one stop lower, i.e. 3200 watt-seconds.<ref>{{cite web |url=http://www.paulcbuff.com/manuals/e640.pdf |title=Einstein – User Manual/Operation Instructions |publisher=Paul C. Buff, Inc |page=13 |accessdate=5 July 2013}}</ref>
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| ===Flash LED illumination===
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| Although they are not yet at the power levels to replace xenon flash devices in still cameras, high-current flash LEDs have recently been used as flash sources in camera phones. The major advantages of LEDs over xenon include low voltage operation, higher efficiency, and extreme miniaturization. The LED flash can also be used for illumination of video recording as well as metering and AF assist.
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| === Focal-plane-shutter synchronization ===
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| Electronic flash units have compatibility issues with [[focal-plane shutter]]s. Focal-plane shutters expose using two curtains that cross the sensor. The first one opens and the second curtain follows it after a delay equal to the nominal shutter speed. A typical modern focal-plane shutter takes about 1/200 s to cross the sensor, so at exposure times shorter than this only part of the sensor is uncovered at any one time. Electronic flash can have durations as short as 50 µs, so at such short exposure times only part of the sensor is exposed. This limits the shutter speed to about 1/200 s when using flash. In the past, slow-burning single-use flash bulbs allowed the use of focal-plane shutters at maximum speed because they produced continuous light for the time taken for the exposing slit to cross the film gate. If these are found they cannot be used on modern cameras because the bulb must be fired *before* the first shutter curtain begins to move (M-sync); the X-sync used for electronic flash normally fires only when the first shutter curtain reaches the end of its travel.
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| High-end flash units address this problem by offering a mode, typically called [[Flash synchronization|FP sync]] or HSS ([[Flash synchronization|High Speed Sync]]), which fires the flash tube multiple times during the time the slit traverses the sensor. Such units require communication with the camera and are thus dedicated to a particular camera make. The multiple flashes result in a significant decrease in guide number, since each is only a part of the total flash power, but it's all that illuminates any particular part of the sensor. In general, if '''s''' is the shutter speed, and '''t''' is the shutter traverse time, the guide number reduces by {{math|{{radical|<var>s</var> / <var>t</var>}}}}<!-- <math>\sqrt{s/t}</math> --><!-- √ (s / t) -->. For example, if the guide number is 100, and the shutter traverse time is 5 ms (a shutter speed of 1/200s), and the shutter speed is set to 1/2000 s (0.5 ms), the guide number reduces by a factor of {{math|{{radical|0.5 / 5}}}}<!-- <math>\sqrt{0.5 / 5}</math> --><!-- √ (0.5 / 5) -->, or about 3.16, so the resultant guide number at this speed would be about 32.
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| Current (2010) flash units frequently have much lower guide numbers in HSS mode than in normal modes, even at speeds below the shutter traverse time. For example, the [http://www.metz.de/en/photo-electronics/mecablitz-models/system-flash-units/mecablitz-58-af-1-digital/product-information.html Mecablitz 58 AF-1 digital] flash unit has a guide number of 58 in normal operation, but only 20 in HSS mode, even at low speeds.
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| ==Technique==
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| [[File:Fill flash.jpg|thumb|right|Image exposed without additional lighting (left) and with fill flash (right)]]
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| [[File:Flash-Direct-Indirect.jpg|thumb|right|Lighting produced by direct flash (left) and bounced flash (right)]]
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| As well as dedicated studio use, flash may be used as the main light source where ambient light is inadequate, or as a supplementary source in more complex lighting situations. Basic flash lighting produces a hard, frontal light unless modified in some way.<ref name=langford>{{cite book
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| | last = Langford
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| | first = Michael
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| | authorlink =
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| | coauthors =
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| | title = Basic Photography
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| | publisher = Focal Press/Butterworth Heinemann
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| | date = 2000
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| | edition = 7th
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| | location =
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| | page = 117
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| | doi =
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| | isbn = 978-0-240-51592-2}}</ref> Several techniques are used to soften light from the flash or provide other effects.
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| *[[Softbox]]es, diffusers that cover the flash lamp, scatter direct light and reduce its harshness.
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| *Reflectors, including [[Umbrella#In_photography|umbrellas]], flat-white backgrounds, drapes and reflector cards are commonly used for this purpose (even with small hand-held flash units).
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| *[[Reflector_(photography)#Bounce lighting|Bounce flash]] is a related technique in which flash is directed onto a reflective surface, for example a white ceiling or a [[Reflector (photography)|flash umbrella]], which then reflects light onto the subject. It can be used as fill-flash or, if used indoors, as ambient lighting for the whole scene. Bouncing creates softer, less artificial-looking illumination than direct flash, often reducing overall contrast and expanding shadow and highlight detail, and typically requires more flash power than direct lighting.<ref name=langford>pp115-8</ref> Part of the bounced light can be also aimed directly on the subject by "bounce cards" attached to the flash unit which increase the efficiency of the flash and illuminate shadows cast by light coming from the ceiling. It's also possible to use one's own palm for that purpose, resulting in warmer tones on the picture, as well as eliminating the need to carry additional accessories.
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| *[[Fill flash]] or "fill-in flash" describes flash used to supplement [[Available light|ambient light]] in order to illuminate a subject close to the camera that would otherwise be in shade relative to the rest of the scene. The flash unit is set to expose the subject correctly at a given aperture, while shutter speed is calculated to correctly expose for the background or ambient light at that aperture setting. Secondary or [[Flash synchronization#Wireless sync|slave flash]] units may be synchronized to the master unit to provide light from additional directions. The slave units are electrically triggered by the light from the master flash. Many small flashes and studio monolights have optical slaves built in. Wireless radio transmitters, such as [[PocketWizard]]s, allow the receiver unit to be around a corner, or at a distance too far to trigger using an optical sync.
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| *Strobe: Some high end units can be set to flash a specified number of times at a specified frequency. This allows action to be frozen multiple times in a single exposure.<ref>{{cite web |url=http://qswags.blogspot.com/2010/06/strobe-tips.html |title=Stobe Tips |publisher=Addendum |date=June 12, 2010}}</ref>
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| *Colored gels can also be used to change the color of the flash. Correction [[Color_correction#Gel_nomeclature|gels]] are commonly used, so that the light of the flash is the same as tungsten lights (using a CTO gel) or fluorescent lights.
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| ==Drawbacks==
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| {{multiple image
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| |align=right
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| |direction=horizontal
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| |header=
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| |footer=Left: the distance limitation as seen when taking picture of the wooden floor. Right: the same picture taken with incandescent ambient light, using a longer exposure and a higher ISO speed setting. The distance is no longer restricted, but the colors are unnatural because of a lack of color temperature compensation, and the picture may suffer from more grain or noise.
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| |width1=220
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| |image1=parket flash.jpg
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| |alt1=The distance limitation as seen when taking picture of the wooden floor
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| |caption1=Flash
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| |width2=220
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| |image2=parket noflash.jpg
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| |alt2=The same picture taken with incandescent ambient light, using a longer exposure and a higher ISO speed setting. The distance is no longer restricted, but the colors are unnatural because of a lack of color temperature compensation, and the picture may suffer from more grain or noise.
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| |caption2=No flash
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| }}
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| * Using on-camera flash will give a very harsh light, which results in a loss of shadows in the image, because the only lightsource is in practically the same place as the camera. Balancing the flash power and ambient lighting or using off-camera flash can help overcome these issues. Using an umbrella or softbox (the flash will have to be off-camera for this) makes softer shadows.
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| * A typical problem with cameras using built-in flash units is the low intensity of the flash; the level of light produced will often not suffice for good pictures at distances of over {{convert|3|m|ft|0}} or so. Dark, murky pictures with excessive [[image noise]] or "grain" will result. In order to get good flash pictures with simple cameras, it is important not to exceed the recommended distance for flash pictures. Larger flashes, especially studio units and monoblocks, have sufficient power for larger distances, even through an umbrella, and can even be used against sunlight, at short distances.
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| * The "[[red-eye effect]]" is another problem with on camera and ring flash units. Since the [[retina]] of the [[human eye]] reflects red light straight back in the direction it came from, pictures taken from straight in front of a face often exhibit this effect. It can be somewhat reduced by using the "red eye reduction" found on many cameras (a pre-flash that makes the subject's [[Iris (anatomy)|iris]]es contract). However, very good results can be obtained only with a flash unit that is separated from the camera, sufficiently far from the [[optical axis]], or by using bounce flash, where the flash head is angled to bounce light off a wall, ceiling or reflector.
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| * On some cameras the flash exposure measuring logic fires a pre-flash very quickly before the real flash. In some camera/people combinations this will lead to shut eyes in every picture taken. The blink response time seems to be around 1/10 of a second. If the exposure flash is fired at approximately this interval after the TTL measuring flash, people will be squinting or have their eyes shut. One solution may be the FEL (flash exposure lock) offered on some more expensive cameras, which allows the photographer to fire the measuring flash at some earlier time, long (many seconds) before taking the real picture. Unfortunately many camera manufacturers do not make the TTL pre-flash interval configurable.
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| * Flash distracts people, limiting the number of pictures that can be taken without irritating them.
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| * Photographing with flash may not be permitted in some museums even after purchasing a permit for taking pictures.
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| * Flash equipment may take some time to set up, and like any [[Grip (job)|grip]] equipment, may need to be carefully secured, especially if hanging overhead so it does not fall on anyone. A small breeze can easily topple a flash with an umbrella on a lightstand if it is not tied down or [[Sandbag#Other_uses|sandbagged.]] Larger equipment (e.g. monoblocks) will need a supply of A.C. power.
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| ==Gallery==
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| <gallery widths="240" heights="175">
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| File:AG-1_flash.tif |Front and back views of an Agfa ''Tully'' flash attachment for AG-1 flashbulbs, 1960
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| File:AG1B flashbulbs with packaging.jpg|A package of AG-1B flashbulbs with an AG-1 flash attachment
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| File:Minolta electronic flashlamp ca 1978.tif|Front and back views of a Minolta ''Auto 28'' electronic flashlamp ca 1978
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| File:Nikon ring light SR2.png|SLR lens with ring flash added
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| </gallery> | |
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| ==See also==
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| * [[Air-gap flash]]
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| * [[Battery–capacitor flash]]
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| * [[Guide number]]
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| * [[Flash synchronization]]
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| * [[Inverse-square law]]
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| * [[List of photographic equipment makers]]
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| * [[Ring flash]]
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| * [[Flash comparison]]
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| * [[Flash-lamp]]
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| * [[Flashtube]]
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| * [[Through-the-lens metering]]
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| ==References==
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| {{reflist}}
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| ==External links==
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| {{Commons category|Photographic flash|Flash (photography)}}
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| * [http://www.galitz.co.il/en/articles/flash.shtml "Flash – Let there be light!"]. Roie Galitz.
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| * [http://photonotes.org/articles/eos-flash/ "Flash Photography with Canon EOS Cameras - Part I"]. PhotoNotes.org. 12 December 2010.
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| * [http://www.mhohner.de/sony-minolta/flashcomp.php "A Minolta/Sony Alpha Flash Compendium"]. Fotografie.
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| * {{PDFlink|[http://www.night-ray.com/PhotoCheatSheet.pdf "Photographic Cheat Sheet"]|87.2 KB}}. Gordon McKinney.
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| * [http://www.dlbrittain.com/FlashCollect.htm List of flashbulbs models]. David L. Brittain.
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| * [http://www.bartziebaphotography.com/html/flashchart.html Flash comparison chart]. Bart Zieba Photography.
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| {{Photography}}
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| [[Category:Flash photography| ]]
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| [[Category:Photographic lighting]]
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| [[Category:Light sources]]
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