What is a good focal length for a reflector telescope?
The main specifications for a really useful first telescope should be: a minimum aperture of at least 90mm for a refractor or 130mm for a reflector and 1,000mm focal length for each. This combination will provide enough light grasp and permit a high enough magnification to see detail on the brighter planets.
What telescope has the longest focal length?
Currently, the largest telescope in operation is the Gran Telescopio Canaris. Its main mirror has a diameter of 10.4 meter (34.12 foot) The actual focal length is 16.5 meter which corresponds to a 16,500mm f/1.586 lens.
Are longer or shorter telescopes better?
Keeping it just to refractor style telescopes; long telescopes have a narrow field of view. Which means, their lens have less curve ground into them. Less curvature means less possible distortions and halos known as chromatic aberration, thus giving a crisper image.
Why is a longer telescope better?
“The bigger a telescope is, the more light it can catch and the better the sharpness of the image becomes.” Larger telescopes enable astronomers to observe fainter objects. Larger telescopes also enable astronomers to observe and analyze planets around distant stars – and maybe find another Earth out there.
Should I get a refractor or reflector telescope?
If you are interested in astrophotography, purchasing a refractor is a better option because of it’s specialized optic design that captures deep space objects like galaxies and nebulae. If you are interested in brighter celestial objects like the Moon or planets or a beginner, a reflector telescope is ideal.
What is the downside of refracting telescopes?
Disadvantages. All refractors suffer from an effect called chromatic aberration (“color deviation or distortion”) that produces a rainbow of colors around the image. This is why the early refracting telescopes were made very long. How well the light passes through the lens varies with the wavelength of the light.
Is it better to have a longer focal length?
Focal length, usually represented in millimeters (mm), is the basic description of a photographic lens. The longer the focal length, the narrower the angle of view and the higher the magnification. The shorter the focal length, the wider the angle of view and the lower the magnification.
Is 1000mm focal length good?
Personally, I consider 1,000mm to be just about the perfect focal length given that the seeing at most amateur observing sites runs about 2 to 3 arcseconds, and your 7.4 inches of aperture will sample that very well.
What is the best focal ratio?
Focal Ratio – Faster, Brighter, Smaller For such objects, a focal ratio of f/10 or more is ideal. But if you want to see wide views of star clusters, galaxies, and the Milky Way, a lower focal ratio is better. You get less magnification, but you see more of the sky.
Is the focal length of a telescope long or short?
* i.e., scopes where long focal length means a long tube, Some of the above factors don’t apply to long focal length telescopes with short tubes such as SCTs and Maks Edited by therealdmt, 30 December 2020 – 08:24 AM.
How is the focal ratio of a telescope calculated?
The specifications for focal length and aperture are measurements given in inches or millimeters (or both), while the focal ratio is calculated by dividing the focal length by the aperture.
Where does the focal length start in a refractor?
In a refractor or a reflecting telescope, the focal length start at the aperture (primary mirror or objective lens) and ends at the focuser where the light rays come together. Generally, when looking at a telescope, it’s safe to assume that a long tube means a long focal length and a short tube means a shorter focal length.
How are refracting telescopes different from reflector telescopes?
Refracting telescopes have a glass objective lens that collects light. As light passes through this lens, they are split into their respective colors or wavelengths. They continue to travel and eventually meet at a focal point within the tube while parallel lightwaves fall onto a focal plane.