三年前樹莓派論壇上有篇名為
《Camera focus distance and macro lenses》
By now there’s plenty of videos and distance shots out there, so I’m concentrating on closer in:
Fixed focus seems quite long and begins at 60cm+ anything closer is blurred:
20cm:
60cm away (those are 30cm rulers)
So I whipped out the cheapy clip on macro lens for my iphone, clipped it over the raspicam and here’s the result:
That’s at 2cm ..bit of a dusty pi 
– now I need some middle ground
……
eckythump wrote:did something similar with a plastic eyeglass, decent pictures at about 12 cm but fairly poor closer or further away. (pictures posted but post awaits moderation), can you tell me which particular macro lens adapter you are using? there are some really cheap ones out there and some less cheap.
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……
For those not into photography and optics, the dioptre value is the reciprical of the focal length in metres, so 1 dioptre is 1m focal length, 2 dioptre 500mm, 4 = 250mm and 10 = 100mm. By putting them in front of a camera lens you shorten the closest focussing point without affecting the focal length too much.
The formula is:
(New closest point) = x/(Dx +1)
where x is the old closest focus point (in metres) and D is the dioptre value of the close up lens.So, if the current lens gives sharpish focus to 2 foot = 600mm = 0.6m, then with a 10dioptre lens the new closest focus will be:
0.6/((10 x 0.6) + 1) = 0.6/(6+1) = 0.6/7 = .086m = 86mm
or about 3.4 inches with similar sharpness.
(I will leave the calculation for other dioptre values as an exercise for the reader
)───
的主題文章，就此展開 RaspiCam
【允許相機】︰
Enable Camera
樹莓派上有一個『 CSI 』 連接器，用來連接相機模組。它需要 GPU 上的『韌體』firmware 支援，這個選項可以『啟用』或『禁用』這個支援。目前樹莓派上提供了三個命令列的應用程式 raspistill ， raspivid 和 raspistillyu 。你可以到這裡下載『RaspiCam Documentation』使用手冊。
目前樹莓派基金會已發行了兩款相機模組，『綠色模組』提供1080p 30fps 的 h264 Full HD 錄影，和 2592 x 1944 畫素的靜態拍照。『咖啡色模組』，基本同於綠色模組，拿掉了紅外線 IR 濾光片，因此可以拍攝紅外線，所以叫做 NoIR 。買時送了一片藍色的濾光片，它的吸收光譜類似於葉綠素，因此能用來調查植物的健康狀況，用於一種稱為 Infragram 的攝像術。
─── 摘自《raspi-config 再探！！》
近攝鏡
近攝鏡（Close-up filter）是一個簡單的二次使用鏡頭（secondary lens），可以安裝在普通鏡頭前實現微距拍攝，而無需使用專門的微距鏡頭。近攝鏡安裝後，可將鏡頭的放大比例增大，讓相機的最近對焦距離得以縮短，得到放大比例的成像。
簡單的近攝鏡可能僅有單片凸透鏡，會造成像差；較為複雜的近攝鏡可能帶有雙合透鏡結構以獲得出色的成像。
三組近攝鏡
傳統的近攝鏡
之討論與應用。
雖然現今尚且無法明白《卡夫卡村》的三光眼鏡到底如何製造︰
不知何時 Mrphs 遞給了我一副眼鏡，說道︰這是小學堂『教具室』研發的『三光眼鏡』，可以觀看而且調變『可見光』、『紅外線』 、『紫外線』的影像顯示。直須戴上就好，和貴處普通眼鏡一般。戴上後，向著『幽竟夢卿』望去，當真是目瞪口呆。只見
星空綺麗
This infrared space telescope image has (false color) blue, green and red corresponding to 3.4, 4.6, and 12 µm wavelengths, respectively.
砂石熒熒
A collection of mineral samples brilliantly fluorescing at various wavelengths as seen while being irradiated by UV light.
草木含情。
心思這個世界在不同的光照下竟會是那麼的奇特美麗。心想為何要叫做『三光』的呢？『教具室』是何處的耶？？剛打算開口問，就聽 Mrphs 講︰『三光』之名來自《三字經》的
意在研究『日月星』的『光譜』與『生命』之關係。當地人都知道這個『教具室』雖只致力研發『教具』與『教材』，事實上卻是《卡夫卡村》尖端之科技的代表，推動『科學教育』目標之實踐。努力『科技護生』宗旨之完成。因此才催促先生快點前行的哩。
今夕何夕欲語無言，只能說光一個『 Infragram 』就需鼓吹多年，
─── 摘自《勇闖新世界︰ W!o《卡夫卡村》變形祭︰感知自然‧幽夢‧四》
眼下令人好奇的是
New closest point = x/(Dx +1)
到底打從哪來？？