How to Calculate the Field of View of the Sky-Watcher SK707AZ2 Refractor Telescope

The area that you can see through your telescope is known as the true field of view or the actual field of view. The field of view of your telescope is determined by the design of the eyepiece of the telescope. Calculating the field of view of a telescope can be done by following a few steps in the proper order.

Difficulty: Easy

Instructions

1. Find out the value of the apparent field of view. Every eyepiece has its own value of the apparent field of view. This value of the eyepiece is supplied from the manufacturer.

2. Find the value of magnification. The value for magnification can be found by dividing the value of the focal length of your telescope by the focal length of the eyepiece. Assuming that your telescope has a focal length of 750 mm and the focal length of the eyepiece is 10 mm, the magnification for your telescope will be 750 / 10 = 75. It is usually denoted as 75X. The focal length for this model is 900 mm.

3. Divide the value of apparent field of view by the value of magnification to get the value of field of view. For example, if the eyepiece has a value of apparent field of view of 50 degrees and a magnification of 75X, then the value of the actual field of view is equal to 50 degrees / 75X = 0.66 degrees.

Tips & Warnings

• Take care that the magnification is not too high and the field of view does not have a very small value. In such a situation, finding the objects you want to watch through your telescope may become a little difficult.
• Ideally, the magnification of your telescope should be 2X per each mm of aperture for good viewing.