Finderscope

One finderscope (also viewfinder or finderscope called ) is a small telescope at low magnification, the parallel to a larger - is mounted - the main telescope. It facilitates the identification of an object in the main telescope because of its weaker magnification and the resulting wider viewing angle.

Application

Means of adjusting screws is provided with its optical axis parallel to the main pipe. In the beam path of the viewfinder crosshairs is mostly placed to facilitate this adjustment and centric adjustment of the star. Most seekers are of the Kepler telescope, so that their image is upside down. For astronomical purposes, does not interfere with the further and avoids loss of light by reversing systems. An Amici prism, which produces an upright and side correct image and a 90 ° viewing angle enables easy orientation in the sky.

Magnification

In search scopes can be found (as well as on any binoculars or binoculars ) Information about magnification and aperture. So is 6 × 30 a six-fold magnification and 30 mm objective aperture. Finder scopes with 5 × 25 or 6 × 30 are often, but rather faint; Better results are obtained using an 8 x 50 telescope or more. At magnifications of 10 ×, however, the finding of objects is becoming increasingly difficult as the field becomes correspondingly smaller, while a larger opening any disadvantages (except higher price and weight) has. The advantage of larger size lies in the better light gathering ability and thus the easier to find faint objects. In telescopes for amateur astronomers therefore four times to a maximum of nine times magnification is common.

Attachment

Simple amateur telescopes usually have only one unstable viewfinder. However, a prerequisite for problem use the viewfinder a stable attachment to the telescope. To avoid transport damages should the viewfinder are secured with a quick release on a mounted on the telescope adapter rail. Alternatively, can be mounted on this adapter, another viewfinder or camera.

Dissemination

For a long time, almost all astronomical telescopes with Einstellkreisen or, increasingly, with digital control are provided, so that the seeker must not be used as often as before. For small telescopes or those with low magnification ( eg for satellite observation) even a visor in the sense of sight and foresight enough.

Also, there are telescopes in which the magnification can be changed to prospect over a folding mirror. A similar function may possibly take a Okularrevolver with interchangeable eyepieces.

Alternatives

Especially for astronomical observations in the amateur astronomy, there are other installation aids:

• The Telrad finder ( separate page )
• The " Rigel quick-finder ", a device resembling the Telrad, but with only two instead of three partial circles. In contrast to the Telrad finder of the Quick-Finder is far less sensitive to dew, the pitch circles have a continuously adjustable pulsing feature. It is especially suitable for telescopes, which require a good balance (eg Dobson telescopes ) Due to the low weight.

• The red dot finder is identical with the reflex sight, a device that raises a point on a specially coated glass surface. Due to the remuneration of the red light dot is clearly visible. Due to the parallel beam path of the light source (usually an LED whose light is guided through an optical fiber ) has the eye unable to focus on the very close point, but sees the star through the " window" you look just as sharp as the luminous point. This type of adjustment aid is only helpful in the visible with the naked eye objects. The red dot finder is very accurate for a ( unique ) adjustment.

Special red dot finder, such as the " PDA - seekers" can optionally also represent target groups or target sign.

• Level with Goto - mount: Use the spirit level the telescope is pointed at the zenith, so that the synchronization of the Goto - mount is accurate enough to safely make a star with main telescope or camera.