After the Telescope

If Santa is going to deliver a telescope after much research and teeth gnashing, that’s great! Your budding astronomer will find any telescopes like those I have posted easy to use and provide nice views.

But, sorry for this, should she or he or they truly embrace the astronomy hobby, that Christmas telescope is just the beginning. But you knew that, right? No? Again, sorry. The astronomy hobby can be a money pit with so many accessories and directions one can go with it.

Eyepieces. Believe me, the ones supplied with most telescopes will need upgrading. Here are options to consider:

Focal Length – determines magnification: Focal length of the telescope ÷ focal length of the eyepiece. Longer eyepiece focal length = lower magnification.

Apparent Field of View (AFOV) – the most comfortable tend to have 52 to 76 degrees AFOV. They are given a variety of names, often based on the optician who invented them.

  • Abbe Orthoscopic – have 4 lens elements and a narrow 40-45 degrees AFOV.
  • Plossl – have 4 lens elements and a natural 50-55 degrees AFOV.
  • Wide Field – various names. Have 4-8 lens elements and a wide 60-76 degrees AFOV.
  • Ultra-Wide Field various names. Have 7-9 lens elements and 80-100+ degrees AFOV.  You have to move your head around to see the entire field of view.

Flat Field – various names. Produce un-distorted views just about to the edge of the visual field. Can be somewhat helpful with fast reflector (f/4 or lower) designs that typically have distortions toward the field edges.

Construction – for wide and ultra-wide field eyepieces those with 6-9 lens elements tend to be of higher quality. Generally, avoid eyepieces with fewer than 4 lens elements.

Barrel Size – common sizes are 1.25” and 2”. 1.25” eyepieces are used for mid-to-high power applications.  2” eyepieces can give wider fields of view and are more commonly used for low to mid power applications.

Coatings – the better eyepieces will indicate they are “fully multicoated”.

Filters. Filters are useful to:

  • Bring out specific details on planets.
  • Improve contrast and reduce the Moon’s brightness.
  • Reduce the effects of achromatic refractor lens chromatic aberrations.
  • Reduce the effects of light pollution.
  • Improve the contrast in nebulae.
  • Safely view the Sun and its various aspects.

Barlow or Amplifier. These optical devices are used in conjunction with eyepieces and multiply the eyepieces magnification. One of these devices can effectively double your eyepiece collection without having to purchase additional eyepieces.

Coma Corrector. An optical device made for fast (f/4 or lower) reflector telescopes. They correct for a distortion called coma that fast telescope’s mirrors typically exhibit.

What’s in the Sky?

December 9; 6:30pm; Astronomy Night at Tye Preston Memorial Library in Canyon Lake.

The 4 gas giant planets lined up: (west to east: Saturn, Neptune, Jupiter, Uranus)