Orion 120mm 9005 Refractor Telescope Optical Tube Assembly. ·
The Orion 120mm 9005 Refractor Telescope Optical Tube Assembly (OTA) is a great choice for amateur astronomers who want to observe distant galaxies, stars, and planets. This telescope features a 120mm aperture, a focal length of 900mm, and a focal ratio of f/7.5. It is constructed with a 2-element air-spaced objective lens and incorporates a 2-element field flattener to reduce chromatic aberration. The OTA also includes a 1.25″ focuser, a 9×50 finder scope, and a 2″ star diagonal.
Optical Elements
The Orion 120mm 9005 Refractor Telescope OTA consists of two optical elements: the objective lens and the field flattener. The objective lens is a doublet, meaning that it consists of two lenses made of different types of glass. The two lenses are air-spaced, meaning that there is a gap between the two lenses filled with air. This type of lens design is beneficial in that it minimizes chromatic and spherical aberration, resulting in a crisp, clear image. The field flattener is also a doublet and is used to further reduce chromatic aberration.
The telescope’s focal length of 900mm and focal ratio of f/7.5 result in an exceptionally wide field of view, making it perfect for astro-photography. This is because the focal ratio is low, meaning that the telescope can collect more light over a larger area. This increases the amount of detail that can be seen in an image and reduces the amount of noise.
The OTA also includes a 1.25″ focuser and a 2″ star diagonal. The focuser is used to adjust the focus of the telescope, while the star diagonal is used to direct the light from the telescope to the eyepiece. It is important to note that the star diagonal is only compatible with 2″ eyepieces.
Finally, the OTA comes with a 9×50 finder scope. The finder scope is used to help locate objects in the night sky. It is a simple telescope that is used to point the main telescope in the right direction.
The Orion 120mm 9005 Refractor Telescope OTA is a great choice for amateur astronomers who want to observe distant galaxies, stars, and planets. Its optical elements provide excellent image quality, while its wide field of view makes it ideal for astro-photography. The included accessories make it even more versatile, allowing for further exploration of the night sky.
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Orion 120ST Short Tube Refractor. The Orion 120ST (Short Tube) is a 120mm achromatic, f/5 refractor. As the Orion ads state, this is designed for wide field., Orion 120mm 9005 Refractor Telescope Optical Tube Assembly.
