TELESCOPE FOR VIEWING THE DEEP SKY
Even though they are all very different, the Deep Sky objects (Galaxies / Nebulae / Star Clusters / Galaxy Clusters / Quasars) usually have two similarities :
► Their large sizes
► Their low brightness
► Large diameter
This is the most important criterion for observing the deep sky. A large telescope will catch more light.
► Wide field
It must be large enough to contain the deep sky objects. So there is no need to buy a telescope with high magnification if you want to dedicate yourself to this field.
► Small focal ratio
As we value the tube diameter over its focal length (which is directly related to the magnification), the focal ratio of an instrument intended for deep sky is often small.
► Long focal length
In order not to have too high magnification which would reduce the field of view (Magnification = Tube focal length / Eyepiece focal length).
► Manual or motorized tracking not
If you want to photograph the deep sky, a motorized mount is essential (motorized equatorial mount or azimuthal with Go-To + field derotator). In visual observation it is not necessary, but avoid you to manually re-orient the telescope when the object goes out of the field of view.
To increase the contrast between the deep sky objects and the night sky, and reveal certain colors.
► Bresser Telescope AC 152/760 Messier EXOS 2 GoTo
► Orion Telescope N 203/1000 Atlas EQ-6 GoTo