What you can see...
  ...and what you WON'T see!
Back to scope choices.....


   First of all, you will NOT see deep space objects in color. Our drawing at left is to illustrate what a nebula would look like in a photograph, or what you might see on the box of a department store telescope.

   But color in dim objects is NOT perceivable by the human eye. It can only be detected on film or by CCD equipment. Color is only perceived by the human eye in bright objects like stars and planets.


   This is more like it. This more closely illustrates how the human eye would  perceive the same nebula in the eyepiece of a telescope. Colors in dim objects (like nebulae and galaxies) can easily be detected and reproduced by photographic film. But for the most part, the human eye sees them only as shades of gray, even with powerful telescopes.


Illustrations © The Belmont Society

   Some newcomers are enticed into astronomy by the visual impact of the color photographs they see. They haven't yet looked through a telescope to see for themselves that deep space objects don't show up in the same stunning colors they've seen in magazines and advertisements. It's unfortunate that the major telescope manufacturers are somewhat responsible for both creating and nurturing this false impression.

   Virtually all manufacturers are eager to publish quality photographs and CCD images that are produced with their equipment. After all, it's a good selling point to show potential buyers that their product will deliver quality performance. Before the advent of color astrophotography this was not a problem. However, somewhere along the line, an "awareness gap" occurred between potential buyers and the 'show-and-tellers', which provokes a disturbing misconception. Look at almost any telescope advertisement these days, and you're likely to see a full-color deep space astrophoto alongside a picture of their product. The unfortunate inference (intended or not) is unavoidable: "That's what you'll see with this telescope".

Aperture rules!

   Secondly, there's a "rule" you must remember: 'Size matters!' Aperture-size, not power, determines how well a telescope will render an image. The quality of an image that you see in the eyepiece depends on a telescope's light gathering ability, which in turn is dependent on aperture size. The amount of power that a telescope is capable of has virtually nothing to do with the quality of the image it delivers, except to say that higher power has a way of actually spoiling an image at times, especially in smaller apertures.

Power vs Aperture - NGC 2841

    This is a good example of a deep space object that's obtainable with almost any size telescope. But to make a point, this image was rendered with two different aperture sizes. The top drawing was done with a 4.5-inch Newtonian at high power; the drawing at the bottom with a large Dob at moderate power. There is no substitute for aperture size! Although many deep space targets are accessible with smaller instruments, you will always get better and clearer views with bigger scopes and darker skies. 

    The moon is a fascinating subject, even with small-aperture telescopes. As illustrated by our sketch at left, a great amount of detail can be seen. Use a lunar filter to cut glare. The moon will tolerate high power, so get out the Barlow!


Drawing © The Belmont Society


   Even with a small aperture you can see quite a lot at moderate power. In fact, a 70mm telescope will put you in touch with a surprising number of celestial objects, including dozens of the Messier's, all the planets out to Jupiter and Saturn, and some very pleasing images of the moon. There are several dozen good small telescopes available, running from a hundred dollars to about $800 for a computerized scope equipped with a GOTO remote. Meade manufactures several popular 70 to 90mm telescopes that are both manual and computerized. Orion offers several also.

   As aperture size increases the price of course goes up, along with the ability to see even more objects. The next popular size over 90mm is 102mm, then 120mm, then 6-inch, 8-inch, etc... all the way up to... well, you name it!

   Remember: deep space objects will NOT appear in living color, but instead will be rendered in 'black and white'. Human eye color sensitivity is more suited for the bright surface tones of planets, and the spectral colors of stars. At times, some nebulae will appear slightly tinted (sometimes green). The color pictures you've seen in magazines are the result of photographic film absorbing light over extended periods (or through CCD processing) - which the human eye is not capable of detecting in darkness.

   Also, you should know that stars will always look like points of light, no matter how much power you use. This is because they are so far away. You can't compress all those light years of distance with an eyepiece.

   The colorful bands and belts of Jupiter, as well as its four major moons, and the rings of Saturn are clearly visible in a 70mm telescope. Mars, Venus and Mercury are visible in a small scope as well, but are extremely reluctant to give up any detail because of their overwhelming brightness. Also, a small telescope will do very nicely on the Orion Nebula and some other prominent Messier objects plus scores of double stars. So it naturally follows that a larger telescope will do even better.

   Uranus and Neptune are also reachable with small telescopes. At opposition, Uranus shines dull green at magnitude 5.6, so that it can actually be seen with 7x50 binoculars and a 3-inch telescope. Neptune - at magnitude 7.7 - is obtainable with a slightly larger telescope in dark skies, but is very difficult to discern against a busy starry background. Both these planets however, can require a great deal of skill and patience to pick out and identify. Pluto, at magnitude 13.7 is visible only in 8-inch or larger apertures (it's almost 40 times farther from the Sun than the Earth is - about 4 billion miles out - and is very small).

   An aperture of 120mm will grab tons of objects. Beyond that, (6-inch, 8-inch, 10-inch, etc) you will begin to see those objects that are referred to as "faint fuzzies", i.e.: - the more difficult nebulae, and many more distant galaxies. At this stage you are limited only by the darkness and clarity of your skies and the quality of your optics.

   An amateur in Australia discovered a probable nova amongst a star cluster in M16 with an 8-inch Newtonian reflector. That's fair proof of the "power" of amateur astronomy! And more recently, Canadian amateur Jack Newton has captured the optical jet of 13th magnitude quasar 3c273 with CCD equipment on a homemade Dobsonian!

Nomenclature - the typical Dob

What's an f/number? - Fast vs slow

The Cost of Amateur Astronomy

Finderscopes, Telrads, etc.

What is "GO-TO"?

Recommendations - GO-TO Systems

Misleading Astronomy

How things REALLY look in the eyepiece

Light Pollution