Tecnologie

Dettaglio dell'articolo:

venerdì 18 gennaio 2013

Apertura del diaframma ed esposizione

F-Stop ed apertura del diaframma

Occorre regolare la quantità di luce che investe il sensore a seconda delle condizioni di luminosità intense o scarse: meno luce del necessario risulterebbe in perdita di pixel e quindi dettagli dell'immagine, mentre una luminosità eccessiva crea molto rumore, rendendo l'immagine più confusa.

La capacità di raccogliere la luce ambientale da parte di un obiettivo viene misurate con quello che viene chiamato rapporto F dell’obiettivo, detto anche f-stop.

Il rapporto F è il rapporto tra la lunghezza focale dell’obiettivo (OF) e il diametro dell’apertura o diaframma (DW):

F= OF/DW

Più basso è il valore del rapporto F , e migliore è la capacità di raccolta della luce dell’obiettivo, quindi  più luce arriva al sensore immagini. Quindi in condizioni di scarsa illuminazione è meglio usare un obiettivo con basso f-stop per avere un'immagine migliore.

I rapporti F sono spesso indicati come F/x, dove 1/x è il rapporto l'apertura del diaframma e la lunghezza focale. Ad esempio un rapporto F/4 indica che il diametro del diaframma è 1/4 della lunghezza focale.

compralo su domuswire  Axis - M1113 Compact Telecamera Axis - M1113, con rapporto
F1.4
compralo su domuswire Axis - M1031-W indoor wireless fixed camera - PIR sensor , LED Lamp and audio support Telecamera da interni Axis M1031, con rapporto F2.0

Tempo di esposizione

Il tempo di esposizione, come suggerisce il nome, indica per quanto tempo il sensore è esposto alla luce nela produzione di una singola immagine. E' chiamato anche durata d'otturazione, l'otturatore è il meccanismo centrale od a tendina che controlla l'esposzione alla luce del sensore.

Un tempo di esposizione più breve è adatto all caso di movimenti rapidi, mentre un'esposizione più lunga serve in condizioni di scarsa illuminazione per migliorare la qualità delle immagini, ma tempi più lunghi dell'appropriato forniscono immagini sfuocate.

Tempi di esposizione più brevi implicano anche tempi di trasmissione delle immagini più brevi, immagini che si succedono più rapidamente, mentre tempi lunghi di esposizione ritardano l'invio dei segnali e diminuiscono la frequenza temporale di invio delle immagini.

compralo su domuswire Axis M3204-V Vandal-resistant and affordable HDTV fixed dome for professional surveillance Axis M3204-V , camera indoor con diaframma fisso e rapporto F1.7, tempi di esposizione da 1/24500 a 1/6 s

 

Le telecamere sono provviste di regolazione manuale di questi parametri, ma i modelli più avanzati regolano automaticamente l'apertura del diaframma ed il tempo d'esposizione, adattandosi alle varie condizioni di luce che si succedono in una giornata carattere questo di fondamentale importanza per ambienti esterni, mentre è più trascurabile per ambienti interni ad illuminazione artificaile costante.

compralo su domuswire
Axis Q1602 Network camera with outstanding image performance in poorlight conditions
Telecamera Axis Q1602 con tempo d'otturazione variabile da 1/29500 s to 2 s. Tempi così lunghi permettono alla camera d'operare in condizioni di luce molto scarse.

Profondità di campo

Una lente od obiettivo focalizza perfettamente oggetti posti ad una determinata distanza, ma oggetti più lontani o vicini perdono gradatamente la loro nitidezza nell'immagine prodotta.

La profondità di campo è definita come la distanza tra l'oggetto più vicino e più lontano che vengono riprersi con nitidezza accettabile.Ci possono essere delle esigenze di ripresa che richiedono d'inquadrare chiaramente soggetti ad una distanza minima, con profondità di campo bassa, od all'opposto è necessario inquadrare chiaramente oggetti posti a distanze diverse, come le targhe di auto in un parcheggio, con profondità di campo ampia.

La profondità di campo è influenzata dalla lunghezza focale e dal diametro del diaframma, una lunghezza focale lunga o un’apertura del diaframma grande limitano la profondità di campo. In base a quanto visto sopra, questo significa che un raporto f-stop F/x con x più elevato migliora la profondità di campo, ma questo implica avere meno luce entrante, con il rischio aggiuntivo di fenomeni di diffrazione causati da diaframmi molto stretti. Inoltre, un campo più profondo risulta essere anche una campo più stretto.

compralo su domuswire
Axis - P1346 Superb HDTV quality and multi-view streaming in any environment

Telecamera Axis P1346 con durata d'otturazione variabile da 1/35500 s a 1/6 s 
e regolazione automatica del diaframma via il sistema P-Iris.

Commenti:

Nonton TV Live Streaming Siaran Langsung Bola Online Malam Hari Ini nobar.fun nonton bola NOBARTV.COM Situs Nonton Bola Online Live Streaming Siaran Langsung Yalla Shoot TV terbaik Indonesia di acara nobar streaming bola Situs Komunitas Fans dan Suporter Bola Mania Indonesia Soccerio.net Fans Bola

Inviato da: siaran langsung bola il: 2018-12-06 16:28:40.824016

May 22, shoe net christian louboutin outlet news, everyone's wardrobe is indispensable to jeans, jeans adidas yeezy christian louboutin sale can be said to be cheap christian louboutin shoes very versatile, but how to jordan 5 match? In order to reflect cheap jordan shoes your unique personal under armour boots taste? cheap jordans Jeans can cheap christian louboutin be described as nike outlet online a year-round nike factory store star cheap christian louboutin never withered, is adidas originals listed as red bottom heels & ldquo; the first of a hundred air max sets of clothes christian louboutin shoes & rdquo;. The fabric and christian louboutin shoes nike outlet store pattern of jeans are also increasing. Especially red bottom shoes now christian louboutin sale the jeans also have christian louboutin sale a good cheap christian louboutin role in red bottom heels self-cultivation, such as straight pants can make thick-legged jordan 11 women nike outlet look healthy and slender, tight pants nike roshe run nike shoes can make fat christian louboutin outlet women christian louboutin outlet become slender, thin red bottom heels women louboutin shoes become sexy nike store and christian louboutin outlet so on. There are many kinds of jeans, especially for many cheap christian louboutin shoes girls, jeans have become very popular nowadays, people are red bottom heels nike outlet store talking air max about christian louboutin sale the characteristics of nike outlet jeans. Up to the upper class society, down to the ordinary people, jeans are everybody, cheap christian louboutin shoes men and women are essential. Especially nike factory store with the improvement of design and nike shoes the research and development nike shoes of christian louboutin material, jeans can jordans for sale interpret a variety of styles on the contrary. It has become a common topic nike air max for jeans brands to adidas outlet narrow the buttocks and slender the legs adidas originals on the louboutin shoes lower nike outlet half of the jordan 5 body.

Inviato da: Mabel il: 2019-04-18 20:15:28.3282

On December 18, Li Bingbing himself preferred the jordan 5 OL style of dressing, which was skillful, gentle and elegant. It is the best spokesperson adidas stan smith for christian louboutin outlet "white bone cheap jordan shoes cheap christian louboutin essence" at present. PS: adidas originals The white bone elite here is christian louboutin sale the pronoun of cheap christian louboutin shoes "white collar, backbone, elite". adidas outlet In christian louboutin outlet Taipei, Li Bingbing attended christian louboutin shoes the press christian louboutin sale conference of the 50th red bottom heels Golden jordans for sale Horse christian louboutin outlet Award red bottom shoes Jury of Taiwan Film. adidas outlet She wore Lanvin's naked pink sleeveless christian louboutin sale pleated skirt, which was cheap christian louboutin shoes christian louboutin shoes concise louboutin shoes and skillful without losing her feminine taste. red bottom heels A adidas superstar commuter dress is cheap christian louboutin instantly upgraded to an louboutin shoes elegant dress with adidas sneakers a dark green super-large adidas nmd necklace. Taipei, the release of the movie "Ghost christian louboutin shoes Castle 5" (Biochemical Crisis 5: Punishment). Li Bingbing is wearing Celine 2012 early autumn series shirts and trousers, low-key color just right, the louboutin shoes length of cheap jordan shoes trousers just right, louboutin shoes shoes just adidas originals right, everything jordans on sale just right. christian louboutin shoes Li Bingbing attended a christian louboutin sale brand event in Beijing. Lightly red bottom shoes jordan 11 red bottom heels handsome trousers have jordans for sale a gentle temperament because of the choice adidas yeezy of light tones, while shirt tops are more lightweight and elegant because adidas yeezy of the cheap jordans use of cheap jordans gauze. Li Bingbing appeared at a fashion event in Beijing. The Gucci dark green adidas sneakers velvet trousers suit shows luxury. jordan 5 The wrinkle details of the jacket cheap christian louboutin shoes add cheap christian louboutin richness jordans on sale cheap christian louboutin shoes to the shape, and red bottom heels red bottom shoes at the same time, highlight jordan 11 the christian louboutin outlet unique delicate image of women. (Cooperative Media: Clothing red bottom shoes Matching) cheap christian louboutin

Inviato da: Cady il: 2019-04-09 15:04:07.630869

remember a word: there are no beautiful legs, only women cheap jordan shoes who nike air max do not know how to wear high heels. Concept shoes art feet "shoes are not jordan 11 just shoes!" adidas sneakers In addition to the height of the heel can modify the legs, this season's personalized, artistic shoes can also nike outlet add color to the legs. nike roshe run nike air max On the 2008 Spring and Summer International T-stage, high-heeled shoes are like works written by surrealist artists, boldly red bottom heels advocating christian louboutin outlet their artistic attitudes. For example, nike shoes designer Mark Jacobs deconstructed the shoes and moved red bottom heels nike factory store the heels to the soles of the feet, which made people eager to test their nike outlet online comfort and balance. Another pair of "artworks" that jordans on sale also made high-heeled shoe enthusiasts crazy christian louboutin shoes was the shoes designed by Mukoya nike outlet store Prada, which were proportionally inlaid with gold and black, matched with materials that were not originally shoes, to create nike outlet store a strong shoe. Art-style carved ceramic nike store high-heeled shoes; and in each season's new shoes design, Carl Lagerfield should not be neglected to surround the transparent glass tube with chains to create a louboutin shoes sexy look for Fendi women's shoes; finally, Stefano Paradise's inspiration for the empty design, YSL high-heeled shoes boldly show the metal bones in front of christian louboutin shoes people, with cheap jordans a laughing cartoon air max louboutin shoes toe. It nike factory store awakens Classical Pop art. cheap christian louboutin TIPS: Don't look weird, but christian louboutin sale they still follow ergonomics from design to production. [Popular Elements] High heel beautification posture is nike factory outlet the so-called: there are christian louboutin sale no beautiful legs, only women nike outlet who do not know how to wear high heels! A pair of knee-crossing leather boots with perfect height, proportion and nike air max line is another waistcoat for women. A pair of high-heeled jordan 5 red bottom heels shoes with bare sexy curve is the nike outlet creator of body charm. This is cheap christian louboutin shoes the important fashion message of "Beautiful Legs Manufacturing Factory" cheap christian louboutin shoes this season: wearing shoes not only for walking more comfortably, but also for christian louboutin shoes changing body proportion and creating air max beautiful legs. Stella Luna, a women's shoe brand devoted to post-modern aesthetics, cheap christian louboutin recently expounded the relationship between high heels nike air max and beautiful legs on a shoe show that was different from other shoe shows. On christian louboutin shoes the conveyor belt of the factory consisting of L-screen light and shadow, the model christian louboutin shoes wearing a pair of high-heeled shoes with heels more than cheap christian louboutin shoes 7cm, incarnated louboutin shoes as a proud, cool and immortal female nike shoes actress, accompanied louboutin shoes by the sound and light effects jordans for sale of Psychedelic rock, metropolitan knight and Gothic Goethe, through live video on the LED screen, created the human body adidas yeezy art paintings of high-heeled shoes and beautiful legs, extremely fine high-heeled sandals, ankle boots nike roshe run and knee-crossing horses. Armor boots... Sixty-six pairs of autumn and winter series high-heeled shoes lengthen the model's legs, making the legs look more slender, expressing the magical power cheap jordans of nike factory store high-heeled shoes adidas stan smith through the visual charm and image effect of an extreme love nike factory store affair. TIPS: From a medical health point of view, the christian louboutin outlet limit of heel nike shoes height on both feet should not exceed red bottom heels 7 cm.

Inviato da: Cady il: 2019-05-06 03:04:24.159797 Shoe web June 16, christian louboutin shoes stripes are undoubtedly one of the most powerful elements in fashion circles. It's simple but distinctive. Whether it's on T-stands or jordan 5 on christian louboutin shoes the adidas outlet christian louboutin sale streets, stripes christian louboutin sale never seem to christian louboutin outlet louboutin shoes be cheap christian louboutin thrown louboutin shoes jordans for sale out of fashion. This christian louboutin shoes season, all red bottom shoes kinds of louboutin shoes jordan 11 dazzling & ldquo; lines & rdquo; cheap christian louboutin shoes cheap christian louboutin are jordans on sale christian louboutin sale red bottom heels traveling in the changeable fashion circle with adidas stan smith a straightforward attitude. adidas sneakers Many fashion people choose stripes to accompany them when they christian louboutin outlet go out. adidas sneakers adidas originals Here's how to red bottom shoes use adidas yeezy stripes to cheap jordan shoes express christian louboutin outlet their cheap christian louboutin unique temperament and lead the jordans for sale cheap christian louboutin fashion cheap jordans adidas superstar in the street. Simple stripe cheap jordans length T, adidas originals adidas superstar classic black and white cheap jordan shoes matching, clean and natural, the cheap christian louboutin shoes sleeve christian louboutin outlet part is loose adidas yeezy design, wide cuffs appear to be very thin arms, adidas nmd long over the cheap christian louboutin shoes cheap christian louboutin shoes hip, can louboutin shoes be worn with underpants and red bottom heels sports shoes, adidas outlet to jordan 11 christian louboutin shoes create a street sports style. Fresh stripe pattern, 5-minute trousers with jordan 5 slender legs, moderate red bottom shoes length, cool red bottom shoes and comfortable, simple adidas nmd matching chiffon blouse red bottom heels with noble christian louboutin sale atmosphere, add highlights to the overall shape. red bottom heels jordans on sale

Inviato da: Leonidas il: 2019-04-23 19:53:31.889655

Scrivi un commento:

Archivio