We are often asked what sort of field of view will one get with the fast F/2 Celestron RASA 8″ imaging telescope.
The answer does depend on the size of sensor in your imaging camera and Celestron state that the image circle is 22mm in diameter which gives a 3.15° field. They also mention that the RASA 8″ has a usable field diameter of 32mm, with a 4.6° view, with some minimal performance loss at edge.
Although its good to have numbers what does this mean in practice from an “illustrative” viewpoint?
As we are now into the time where the sky is dark enough to do some imaging, we decided to pick a selection of autumnal objects that are visible after sunset and before midnight. Using Stellarium we entered the necessary parameters of the RASA 8″ and selected a popular CMOS camera with a diagonal size close to Celestron’s quoted 22mm image circle. We then used the Stellarium program field-of-view overlay to see the resulting field of view and how each object could be captured. The field of view with the camera-RASA 8″ is shown with a yellow rectangle.
We hope you find this useful to visualise and give some indication of how a small selection of autumnal targets would appear with such a camera-RASA 8″ telescope configuration. For some objects the camera could of course be rotated for better framing but it gives you a general idea of how the objects would appear.
North America and Pelican in Cygnus
Butterfly nebula around Sadr in Cygnus
Crescent nebula in Cygnus
Veil Nebula in Cygnus
NGC6823/6820 in Vulpecula
Lagoon and Triffid nebula in Sagittarius
Double Cluster in Perseus
Heart Nebula in Cassiopeia
Soul Nebula in Cassiopeia
IC1396/Elephants Trunk Nebula in Cepheus
NGC7822 in Cepheus
M33 galaxy in Triangulum
The Andromeda galaxy Messier 33.
As a final comparison below is the Andromeda galaxy with the same camera but how the field of view would be attached to a same size aperture 8″ (but F/10) SCT telescope. You can see looking above how wide the field of view is with the 8″ aperture RASA 8″ compared to that with an 8″ SCT (below).
The Celestron 8″ RASA is available direct from ourselves. The size and weight of the telescope means that is can be used on medium sized mounts such as the Celestron Advanced VX and above.