Binorum Kellner 25mm 50° 1.25 Low Magnification Telescope Eyepiece

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Binorum Kellner 25mm 50° 1.25″ Eyepiece

Article No.: 77353
Manufactured by: Binorum
Shipping weight: 0.08 kg

Our price: 25.15 €

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This product is available in the following variants:
Binorum Kellner 6mm 50° 1,25″ Eyepiece	24.30 €
Eyepiece Binorum Kellner 10mm 50° 1,25″	24.50 €
Binorum Kellner 15mm 50° 1.25″ Eyepiece	24.95 €
Binorum Kellner 20mm 50° 1.25″ Eyepiece	25.15 €
Binorum Kellner 25mm 50° 1.25″ Eyepiece	25.15 €

Binorum Kellner 25mm 50° 1.25″ Eyepiece

The Kellner eyepiece design offers reliable optical performance at an accessible price point. This 25mm focal length eyepiece features a classic 3-element construction with a 50° apparent field of view, ideal for low magnification wide-field observations of the night sky.

The eyepiece is suitable for basic refractor and reflector telescopes with standard 1.25″ focusers. The 25mm focal length provides comfortable low magnification, perfect for viewing large star clusters, extended nebulae, the full lunar disk, and scanning rich Milky Way star fields. Multi-coated optics ensure good light transmission and contrast.

Key features include metal barrel construction for durability, filter threads for adding moon or light pollution filters, and a rubber eyecup for comfortable viewing. The generous eye relief makes extended observing sessions comfortable for most observers. This eyepiece serves as an excellent starting point for beginners or as a wide-field addition to any eyepiece collection.

Binorum eyepieces combine time-proven optical designs with modern manufacturing quality control, delivering dependable performance for amateur astronomers. Each eyepiece undergoes rigorous testing to ensure consistent optical quality and mechanical precision at an exceptional price-to-performance ratio.

Specifications

Type of eyepiece: Kellner

Focal length: 25 mm

Connection type: 1.25″

Apparent field of view: 50°

Telescope parameters using this eyepiece

Aperture mm

Focal length telescope mm

Specifications:

Magnification:

Telescope magnification is calculated by dividing the telescope's focal length by the eyepiece focal length. A Barlow lens also affects magnification: the power increases according to the Barlow's multiplication factor.

Field of View:

The field of view is the angular size of the sky area visible through the telescope with a given eyepiece. It depends on both the magnification and the eyepiece's apparent field of view. For comparison, the Moon's average apparent diameter is 0° 31' 5" (0.518°).

Exit Pupil:

The exit pupil is the diameter of the light beam that exits the eyepiece and enters your eye. A larger exit pupil produces a brighter image. Exit pupil is calculated by dividing the aperture diameter by the magnification.

Focal Ratio:

The focal ratio (also called f-number or f-stop) is the ratio of the telescope's focal length to its aperture diameter. Telescopes with focal ratios from f/4 to f/6 are typically called "fast" telescopes, suitable for both visual observation and astrophotography. Telescopes with focal ratios between f/6 and f/15 are better suited for visual observation than photography, and generally make it easier to achieve higher magnifications.

Resolution (Dawes Limit):

Resolution is the angular size of the smallest details and objects that can be distinguished through this telescope under excellent observing conditions. This theoretical limit assumes perfect optics and atmospheric conditions.

Limiting Magnitude:

This is the faintest star magnitude visible through this telescope under excellent observing conditions with dark, clear skies and a fully dark-adapted eye.

Magnification with this eyepiece

330

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480

500

600

650

660

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750

770

800

13x

14x

16x

17x

18x

19x

20x

24x

26x

28x

30x

31x

32x

880

900

920

1000

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1250

1400

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1800

2000

2350

2800

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3910

35x

36x

37x

40x

48x

50x

56x

60x

72x

80x

94x

112x

120x

156x

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