How Do I Determine The Field Of View For My Ccd Chip And Telescope

How do I determine the field of view for my CCD chip and telescope?

You must have peeked at the sky using your telescope countless of times. Have you ever wondered how much of the sky you are observing?

Or what could help you identify the celestial objects that you see? If that is the case, we have a case to make.

Follow along to learn about the calculations on the field of view. We also have some insight into ingenious CCD chips.

What are CCD chips?

Charged Couple Devices (CCDs) are photon detectors. They are typically used in telescopes. They replace a camera in the telescope to produce images.

A CCD is a present as a tiny chip in the telescope. It consists of large grids called Pixels. Pixels are the elements that sense the photons.

The light collected by the telescope is focused on the CCD chip. When light reaches the Pixels on the chip, electrons are released.

You can calculate the total number of electrons released. This helps in determining the amount of falling on the CCD chip.

The Area of pixels is the amount of coverage. The pixel denotes an image’s resolution.

What are the advantages of CCD chips?

CCD chips were an ingenious technology, especially for astronomers. It has simplified several fields of astronomy ever since its inception.

Consider the following advantages of CCD chips:

  • Better sensitivity and noise reduction.
  • Lesser defective pixels. This is possible due to the simplicity of the structure.
  • Homogenous images.

What is a CCD telescope?

CCCD telescope is infamous for producing clear images of celestial objects. It is quite similar to any other telescope, structurally.

Instead of an eyepiece, a special camera is mounted at the front of the scope. While looking at celestial objects, we are risking exposure.

A CCD chip eliminates this risk. The CCD camera makes all the difference. It continually collects photons reducing the exposure on your eyes.

What is the field of view of a telescope (fov)?

Calculating the field of view of an imaging image is vital for several reason. Out of those, the main goal is to know how much of the sky is visible to you.

This enables you to compare the charts with your calculation. This will help you find what celestial object you are observing.

The amount of galaxy you can view with an imaging device varies dramatically. Therefore, astronomers are so anal about eyepieces offering a wider field of view.

How to determine the field of view of a telescope?

Typically, eyepieces mention the necessary calibrations. Calibrations such as apparent field of view and focal length.

Apparent Field of View

The apparent field of view the amount of sky visible through an eyepiece. This is true when the eyepiece is detached from the telescope.

The True Field of View

The true field of view is also the measure of how much the sky is visible to you. Now, the eyepiece is attached to the telescope.

You can find the true field of view through the following formula:

True field of view = apparent field of view ÷ magnification

Magnification of the telescope can be calculated with the focal length. Divide the telescope’s focal length with the Eyepeice’s focal length.

How to determine the field of view for a CCD chip?

There are two essential variables that you need to figure out for this process. The size of the sensor of the CCD chip. And the focal length of your telescope.

The field of a CCD chip is the total amount of coverage it offers for observation. The field of view of a CCD is determined using twp factors. The size of the CCD chip and the focal length of the telescope.

For instance, each CCD has 1,000,000 pixels. Each pixel is 25µm × 25µm. The size of the pixel is 1.25 arc seconds.

Then the field of view is number of Pixel in CCD multiplied by the pixel size. the field of view in this case is 1250 arc seconds.

Formula for determining the field of view of your imaging device.

The presented formula might appear too simple. And you are right, it is. The formula is an approximation of another complicated calculation.

You have the sensor size of the CCD chip and the telescope. All there is left to do it to apply the following formula:

(135.3 × D) ÷ L

Here, D- is the size of the sensor of the CCD chip (in mm). L- is the focal length of the telescope (in inches).

To employ this formula, you must have the same units for both components. This formula gives you a field of view in arc minutes. If you wish to have it in degrees or minutes, convert accordingly.

Recommended Reading:


  1. Universe Optics
  2. Love the Night Sky
  3. Mark Thompson Astronomy
  4. Panavision
  5. Optique Ingenieur
  6. Celestron