The coma corrector is a very important accessory for all NEWTON telescopes with an aperture ratio between f/3.5 and f/6 , especially for photographic use.
With this corrector you can also correct the field on cameras with large sensors up to full format ("FULL FRAME") .
On the inside (camera side) there is a 2" filter thread , e.g. for using a narrow band filter or a light pollution filter.
The Artesky coma corrector also reduces the focal length of your Newtonian telescope:
For example, a Newtonian with a native focal length of f/4 is reduced to a resulting focal length of f/3.4. This shortens the exposure times considerably and also results in a fully illuminated field of view - ideal for recordings with full-frame DSLR cameras!
Compatible for Newtonians between 150mm and 300mm aperture with a focal ratio between f/3.5 and f/6.
Field: Full Frame
Optical elements: 4 optical elements with multi-coating
Outer Diameter: 76.3mm (3")
Back focus: 55mm
Total length of the corrector: 119.81mm
What is coma and what causes it?
Coma is an optical aberration that derives its name from the classic comet-like appearance (coma = tail of a comet).
The coma occurs when the imaged object (eg a star) is moved laterally by a certain angle with respect to the axis of the system. The rays passing in the periphery of the optical axis are focused at a different point on the axis. This gives the star a "tail" and makes it look like a small hook. This effect occurs mainly on fast Newtonian telescopes in the peripheral area of the field of view. A ray of light passing through the lens at a certain distance from the center is focused in a ring on the focal plane. The overlapping of these different rings creates a V-shape similar to the tail ("coma") of a comet.
As with spherical aberration in refractors, coma can be reduced or even completely eliminated by using suitable coma correctors for the affected optical system.