I Can't See Anything Clearly Through My Telescope At Night

I can’t see anything clearly through my telescope at night

Have you just bought a new telescope? You are excited about what wonders you will come across? The night sky is the most enchanting for astronomers.

But what if your view of the celestial bodies is pitch black darkness. No, it isn’t the sky that’s empty. It’s your telescope and the technique that needs some guidance.

If you are not able to see anything through your scope now, Don’t fret. After you are through with this article. Your observation will be as clear as day, even during night-time.

Considerations for choosing the right eyepiece for you telescope

Not every eyepiece works well with every telescope. Even a particular situation can ruin the view if you are not careful. The maximum recommended magnification is a critical deliberation.

Keeping within the limits of 50x per inch of the scope’s aperture is a universal rule. If you go beyond 50x, the view will surely get dim and blurry.

During the night when the viewing conditions are average, the magnification is 30x or 40x.

It is best to choose an eyepiece that works for all nights rather than a few.

Maximum magnification is limited because of several factors. Your eye power, the eyepiece’s exit pupil, and the telescope are the significant factors.

What is an exit pupil of an eyepiece?

The exit pupil is a vital consideration for deciding the magnification of an eyepiece. Under darker conditions, the eye’s pupil only opens up to 7mm in diameter.

If you are older than 40 years of age, this diameter further drops to 5 or 6mm. The specific diameter to which your eye opens in the dark limits the exit pupil of the eyepiece.

In case the exit pupil is higher than this diameter, no light will enter the eye. If that happens, the vision at that moment is practically wasted.

In reflecting telescopes, the exit pupil is a more significant concern. This is due to the central obstruction in the secondary mirror.

Refracting telescopes don’t have central obstruction. Therefore, this is not a problem with this kind of scope.

Is there an optimum magnification for a telescope?

The optimum magnification for a telescope isn’t available as a fact. However, for deep-sky objects, experts use an exit pupil of 2mm.

At this diameter of 2mm, the light falls on your retina’s most sensitive region. This makes up for the best visual experience for astronomers.

It is important to stress that there is no precise guideline for exit pupil measurement. As the magnification gets higher, objects get dimmer. This is especially true for extended objects such as nebulae and galaxies.

Your telescope collects the same amount of light no matter the eyepiece. This is a fundamental law of physics applies to all kinds of astronomy.

Can’t see anything through your telescope at night? Here are some solutions to your problem.

Here are some pointers that will most likely help you troubleshoot the problem:

Get more practice during daytime

If visibility is a problem at night, we suggest that you practice in the morning. You can learn, focus, aims, and alignment of the scope easily in sunlight.

Eyepiece troubleshooting

Begin with a low powered eyepiece. To avoid confusion, low powered eyepieces have higher calibration. The calibration is typically present around the eyepiece in millimetres.

A low-powered eyepiece has a wider field of view. As a beginner, you will find it helpful to aim and focus better with such an eyepiece.

The drawtube is a 2-inch tube located on the posterior side of a refractor scope. Whereas in a reflector telescope, it is present at the front-side end.

Find the drawtube depending on the type of telescope you have. Insert the eyepiece in the tube and rotate to tighten it securely.

Aiming for a distant object

Point your telescope at a landscape located hundreds of yards away. The infinity focus of the telescope is meant for viewing objects even further in the sky.

For aiming, you can hold the tube from behind. Now move the scope while keeping an eye on the tube.

Once you find the right aim, clamp both axes of the scope. This ensures that the telescope is stable and secure. You can also pan the handle of the scope for stability.

Now peek through the eyepiece, from behind the scope. Do not place your eye right against the lens of the eyepiece. This will cause strain for your eyes.

Turn either of the two knobs sidewise or in the direction of the drawtube. Turn the knobs simultaneously until you have the terrestrial aim in the scope’s focus.

Recommended Reading:

References

  1. Agena Astro
  2. Sky and Telescope
  3. Physics Forums
  4. Cloudy Nights
  5. Cosmoquest
  6. Celestron

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