巴別塔
巴別塔（敘利亞語：ܡܓܕܠܐ ܕܒܒܠ，Maḡdlā d-Bāḇēl 希伯來語：מִגְדַּל בָּבֶל，Migdal Bāḇēl）；也譯作巴貝爾塔、巴比倫塔，或意譯爲通天塔），本是猶太教《塔納赫·創世紀篇》（該書又被稱作《希伯來聖經》或者《舊約全書》）中的一個故事，說的是人類產生不同語言的起源。[1][2][3][4] 在這個故事中，一群只說一種語言的人在「大洪水」之後從東方來到了示拿（希伯來語：שנער）地區，並且決定在這修建一座城市和一座「能夠通天的」高塔；上帝見此情形，就把他們的語言打亂，讓他們再也不能明白對方的意思，還把他們分散到了世界各地。
根據一些現代學者的看法，巴別塔和一些已知的建築物之間存在聯繫，其中一個十分著名的就是「埃特曼安吉神廟」，一座由巴比倫尼亞國王那波帕拉薩爾修建獻給美索不達米亞的神馬爾杜克的塔廟（大約是在公元前610年建造）。[5][6] 這座「巴比倫大金字塔 」高91公尺（300英尺）。亞歷山大大帝在公元前331年左右下令拆毀這座神廟好在原址上建造他的陵墓。[7][8] 在蘇美爾故事《恩麥卡爾和阿拉塔王》中也出現了相似的情節。[9]
在《光的世界…》系列文本之尾篇，特別提醒讀者
數位相機
數位相機（英語：Digital Camera），是一種利用電子感測器把光學影像轉換成電子數據的照相機，有別於傳統照相機通過光線引起底片上的化學變化來記錄圖像。「數碼」一詞原本是英文Digital（數字的）的港式翻譯，後來傳入大陸，而台灣則使用「數位」。依功能、構造與畫質的不同，目前較常見的數位照相機可區分為消費型數位相機（俗稱傻瓜相機）、類單眼數位相機、數位單鏡反光相機及無反光鏡可換鏡頭相機4種。另也有針對極為專業的特殊需求而設計的數位中片幅（120片幅）相機。
在數位相機中，光感應式電荷耦合元件或互補式金屬氧化物半導體感測器用來取代傳統相機底片的化學感光功能。被捕捉的圖像數據經集成的微處理器通過一定算法編碼後，儲存在相機內部數位存儲設備（記憶卡、微型硬碟、軟碟或可重寫光碟）中。隨著快閃記憶體容量的大幅增加和價格的下降，目前絕大多數數位相機都已採用快閃記憶體作為儲存方案。
雖然早期電子元件性能不佳，但由於數位相機小巧輕便、即拍即有 、使用成本低、相片方便保存、分享與後期編輯等諸多優點，而且畫質進步極快，使其在短 時間得到迅速普及。大部分數位相機兼具有錄音、攝錄動態影像等功能。2009年，全球共售出數位相機（包括帶數位相機功能的手機）超過9億部，而傳統相機 已近乎在市場上絕跡。目前，越來越多的設備如手機、個人數字助理、個人電腦、終端機及平板電腦等也整合進了數位相機功能。
，雖然逐漸取代了過去的膠卷相機，然而許多傳統術語依舊存在。其一就是焦距之巴別塔，它來自各種不同尺寸之感測器
Sensor size and angle of view
Cameras with digital image sensors that are smaller than the typical 35mm film size have a smaller field or angle of view when used with a lens of the same focal length. This is because angle of view is a function of both focal length and the sensor or film size used.
The crop factor is relative to the 35mm film format. If a smaller sensor is used, as in most digicams, the field of view is cropped by the sensor to smaller than the 35mm full-frame format’s field of view. This narrowing of the field of view may be described as crop factor, a factor by which a longer focal length lens would be needed to get the same field of view on a 35mm film camera. Full-frame digital SLRs utilize a sensor of the same size as a frame of 35mm film.
Common values for field of view crop in DSLRs using active pixel sensors include 1.3x for some Canon (APS-H) sensors, 1.5x for Sony APS-C sensors used by Nikon, Pentax and Konica Minolta and for Fujifilm sensors, 1.6 (APS-C) for most Canon sensors, ~1.7x for Sigma‘s Foveon sensors and 2x for Kodak and Panasonic 4/3-inch sensors currently used by Olympus and Panasonic. Crop factors for non-SLR consumer compact and bridge cameras are larger, frequently 4x or more.
| Table of sensor sizes[9] | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Type | Width (mm) | Height (mm) | Size (mm²) | |||||||||||
| 1/3.6″ | 4.00 | 3.00 | 12.0 | |||||||||||
| 1/3.2″ | 4.54 | 3.42 | 15.5 | |||||||||||
| 1/3″ | 4.80 | 3.60 | 17.3 | |||||||||||
| 1/2.7″ | 5.37 | 4.04 | 21.7 | |||||||||||
| 1/2.5″ | 5.76 | 4.29 | 24.7 | |||||||||||
| 1/2.3″ | 6.16 | 4.62 | 28.5 | |||||||||||
| 1/2″ | 6.40 | 4.80 | 30.7 | |||||||||||
| 1/1.8″ | 7.18 | 5.32 | 38.2 | |||||||||||
| 1/1.7″ | 7.60 | 5.70 | 43.3 | |||||||||||
| 2/3″ | 8.80 | 6.60 | 58.1 | |||||||||||
| 1″ | 12.8 | 9.6 | 123 | |||||||||||
| 4/3″ | 18.0 | 13.5 | 243 | |||||||||||
| APS-C | 25.1 | 16.7 | 419 | |||||||||||
| 35 mm | 36 | 24 | 864 | |||||||||||
| Back | 48 | 36 | 1728 | |||||||||||
Field-of-view crop in cameras of different sensor size but the same lens focal length.
Relative sizes of sensors used in most current digital cameras.
以及攝影中所謂 35 mm 等效焦距之說法︰
35 mm equivalent focal length
In photography, the 35 mm equivalent focal length is a measure that indicates the angle of view of a particular combination of a camera lens and film or sensor size. The term is useful because most photographers experienced with interchangeable lenses are most familiar with the 35 mm film format.
On any 35 mm film camera, a 28 mm lens is a wide-angle lens, and a 200 mm lens is a long-focus lens. However, now that digital cameras have mostly replaced 35 mm cameras, there is no uniform relation between the focal length of a lens and the angle of view, since the size of the camera sensor also determines angle of view, and sensor size is not standardized as film size was. The 35 mm equivalent focal length of a particular lens–sensor combination is the focal length that one would need for a 35 mm film camera to obtain the same angle of view.
Most commonly, the 35 mm equivalent focal length is based on equal diagonal angle of view.[1] This definition also in the CIPA guideline DCG-001.[2] Alternatively, it may sometimes be based on horizontal angle of view. Since 35 mm film is normally used for images with an aspect ratio (width-to-height ratio) of 3:2, while many digital cameras have a 4:3 aspect ratio, which have different diagonal-to-width ratios, these two definitions are often not equivalent.
The resulting images from 50 mm and 70 mm lenses for different sensor sizes; 36×24 mm (red) and 24×18 mm (blue)
閱讀鏡頭規格時，務須留心也！