วันจันทร์ที่ 15 พฤศจิกายน พ.ศ. 2553

Twin-lens reflex camera

A twin-lens reflex camera (TLR) is a type of camera with two objective lenses of the same focal length. One of the lenses is the photographic objective (the lens that takes the picture), while the other is used for the waist-level viewfinder system. In addition to the objective, the viewfinder consists of a 45-degree mirror (the reason for the word reflex in the name), a matte focusing screen at the top of the camera, and a pop-up hood surrounding it. The two objectives are connected, so that the focus shown on the focusing screen will be exactly the same as on the film. However, many inexpensive TLRs are fixed-focus models. Most TLRs use leaf shutters with shutter speeds up to 1/500th sec with a B setting.
For practical purposes, all TLRs are film cameras, most often using 120 film, although there are many examples which used other formats. No general-user digital TLRs exist, since their heyday ended prior to the digital era. The main specialist/collector-oriented exception is the Rollei Mini-Digi, introduced as a rather expensive "toy" in 2004

Ukulele


The ukulele, (pronounced /ˌjuːkəˈleɪliː/ EW-kə-LAY-lee,[1] from Hawaiian: ʻukulele [ˈʔukuˈlɛlɛ]; variantly spelled ukelele in the UK), sometimes abbreviated to uke, is a chordophone classified as a plucked lute; it is a subset of the guitar family of instruments, generally with four nylon or gut strings or four courses of strings.[2]
The ukulele originated in the 19th century as a Hawaiian interpretation of the cavaquinho or braguinha and the rajão, small guitar-like instruments taken to Hawaiʻi by Portuguese immigrants.[3] It gained great popularity elsewhere in the United States during the early 20th century, and from there spread internationally.
Tone and volume of the instrument vary with size and construction. Ukuleles commonly come in four sizes: soprano, concert, tenor, and baritone.