Celestron 8" RASA (Rowe-Ackermann Schmidt Astrograph): A field of view example

Celestron 8" RASA (Rowe-Ackermann Schmidt Astrograph): A field of view example

Last week we published an introductory blog about the new 8" version of Celestron's Rowe-Ackermann Schmidt Astrograph outlining its main features. To read that blog see >>here<<. In this short blog we will look at an example of the field of viewing you can get using one of the popular astroimaging cameras currently available.

RASA 8" with camera attached

Celestron 8" RASA with a camera attached.

We at David Hinds Ltd are really looking forward to this 8" version of the RASA (Rowe-Ackermann Schmidt Astrograph) being released and becoming widely available (see our dealer list >>here<<). This telescope will open the door, to many people, to fast wide field imaging, as the scope

  • is affordable
  • is not bulky - at only 628mm (24.7" long), 235mm (9.3") in diameter
  • is not heavy - weighing only 7.7kg (17lb) 

Its relatively low weight means that the RASA 8" can easily be used on mid range, affordable and very popular mounts (rather than very heavy, bulky, usually permanently-sited mounts). This also means the telescope (and suitable) mount can be easily transported to dark sky sites too to image your favourite celestial targets.

So with targets in mind, what will the field of view with the RASA 8" be like?

That will depend on the camera that you would use. The RASA 8" was optimised to be used with cameras having sensors with up to a 22mm diagonal, although APS-C sized sensors can also be used. To show that the field of view could be like with the RASA 8", we have chosen a popular camera with a 16Mp sensor, having a diagonal size of 21.9mm (ASI 1600) - so is just about the right size for the optimised field of view - results in a field of view of 2.53°x1.91° (the RASA 11" the field of view is 1.63°x1.23° and for the RASA 36/14" it is 1.28°x0.97° using the same camera).

So what are these fields of view like "on the sky"? 

Below we show the approximate fields of view, based on the aforementioned 16Mp camera, for the RASA 8", 11" and 14" models using a ppular winter target - the Orion Nebula, Messier (M) 42.

Celestron RASA field of view comparisons

Image above shows an image taken with the RASA 8 taken by Michael Jager who used a popular ASI 1600 16Mp camera and Baader RGB filters. Also shown for reference is the field of view with a RASA 11" (green box) and RASA 36cm/14" (yellow box). 

As can be seen from the image above, the short focal length of the RASA 8" gives a nice wide field of view around the Orion nebula. Its field of view also encompasses the 'Running Man nebula', that sits just above Orion nebula, too. The field of view of the RASA 11" (green) and 14" (blue) using the same camera are also shown for comparison (we will discuss the RASA 11" and 14" models and their features in later blogs). If you want to know what the field of view will be like with a camera that you own, or may be considering, please send email us at: contact@dhinds.co.uk (or via our contact form page >>here<<).

The RASA 8" telescope will be an ideal instrument and ideally suited for those wanting a portable, affordable, telescope to capture images of large celestial objects (such as Andromeda Galaxy, Horsehead nebula, Rosette nebula and much more) quickly (short exposure times) and easily (guiding not always required). 

Watch out for our next blog on the RASA 8" soon.....

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