Reticle

Under reticle or reticle of a measurement or other telescope refers to the attached on the inner side of the eyepiece glass plate with fine lines.

They are used for estimation or measuring small angles and are either delicately engraved or photographically exposed on the glass.

The name comes from the filaments, which were previously used for its fineness. For important measurements until about 1920 even special spiders were taken away in a box.

The simplest case of a reticle is the crosshair. The micrometer, a particularly close-knit reticle allows for precise angle and distance measurement and is mainly used in astrometry and microscopy. For astronomical instruments there were simple explanations around 1700, for microscopes in the 19th century.

Provides you the crosshair of theodolite on an object whose horizontal and vertical angles can be measured simultaneously. Somewhat accurate the separate setting (at 30 -fold magnification approximately 1 ").

Reticle

The reticle is located in the inner ( object side ) focal point of the eyepiece and therefore appears to the normal eye sharp. In wide - or short-sightedness, there is a diopter compensation.

In focusing of the telescope at infinity ( in fact from a few kilometers ), the glass plate is in the focal point of the lens. If the observed object closer, the telescope is extended by an extendable tube, or move an inner focusing lens.

The reticle may consist of a few lines or have an entire reticle. The latter is common in astronomy and astrometry in order to achieve a higher accuracy in position or time measurement.

Theodolite

In general, simpler thread nets are used in geodesy; usually the more important vertical thread is twice per half and easily. The double thread has about 20 " spacing and is suitable for calibrating many goals:

• Ranging Pole (escape rod ) from distances 10-200 meters
• Bar from distances of about 20-500 meters
• Steeple or chimney of a few kilometers.

Military Telescopes

The so-called reticle often have strokes or a reticle in line graduation ( 6400 lines are 360 °). The distance calculated is as follows:

Distance = 1000 × size of the object / number of bars that fills the object in binoculars.

Example: a car ( length approx 6 meters ) covers 12 strokes.

1000 × 6 m / 12 = 500 m (distance observer - car).

Marine binoculars

These have a reticle often yields a vertical and a horizontal reticle, these are used for distance determination, vertical bar pitch: distance = ( object size / number of lines) × 100

Special feature of the horizontal lines: This show half increment because object is taken in the middle, and on one side of the stroke size is read. The graduated scale is divided here into degrees so that the distance of about radians = ( object size / number of lines) × ( 360/2π ) = ( object size / number of lines) × 57.32 calculated.

In many glasses, a compass is displayed.