Search results
Results from the WOW.Com Content Network
An improvised pinhole has a similar but better effect. The same principle has also been applied as an alternative to corrective lenses: a screen of pinholes is mounted on an eyeglass frame and worn as pinhole glasses. Differential diagnosis: pinhole worsen vision: Macular diseases, [5] central lens opacities [6] Vision static with pinhole ...
Pinhole glasses, also known as stenopeic glasses, are eyeglasses with a series of pinhole-sized perforations filling an opaque sheet of plastic in place of each lens. Similar to the workings of a pinhole camera , each perforation allows only a very narrow beam of light to enter the eye which reduces the size of the circle of confusion on the ...
The first known example of a tumbler lock was found in the ruins of the Palace of Khorsabad built by king Sargon II (721–705 BC.) in Iraq. [1] Basic principles of the pin tumbler lock may date as far back as 2000 BC in Egypt; the lock consisted of a wooden post affixed to the door and a horizontal bolt that slid into the post.
A home-made pinhole camera lens A pinhole camera is a simple camera without a lens but with a tiny aperture (the so-called pinhole )—effectively a light-proof box with a small hole in one side. Light from a scene passes through the aperture and projects an inverted image on the opposite side of the box, which is known as the camera obscura ...
The M42 lens mount is a screw thread mounting standard for attaching lenses to 35 mm cameras, primarily single-lens reflex models. It is more accurately known as the M42 × 1 mm standard, which means that it is a metric screw thread of 42 mm diameter and 1 mm thread pitch.
Lenses that support it include those labelled 'SMC Pentax', 'SMC Pentax-M' and 'SMC Pentax-A'. These K-mount bodies cannot use lenses that lack an aperture ring, such as FAJ or DA. K-mount lenses can be used on all Pentax bodies, but are restricted to stopped down mode when used with "crippled" K AF-mount bodies (see below).
In this arrangement, the eye lens is a plano-concave/ double convex achromatic doublet (the flat part of the former facing the eye) and the field lens is a double-convex singlet. A reversed Kellner eyepiece was developed in 1975 and in it the field lens is a double concave/ double convex achromatic doublet and the eye lens is a double convex ...
Virtual manuals help manufacturers adapt to rapidly-changing product designs, as digital instructions are more easily edited and distributed compared to physical manuals. [161] Digital instructions increase operator safety by removing the need for operators to look at a screen or manual away from the working area, which can be hazardous.