Welcome to Binoculars 101

I am assuming you are thinking about purchasing binoculars, otherwise you wouldn’t have navigated to this page. There are many things to consider before buying. I hope the following information will help you choose the correct instrument for your situation.

                                Things to Consider:

  1. 1. Are they primarily going to be used for astronomy?

  2. 2. Are they going to be used just by you and/or family member?

  3. 3. Do you wear glasses?

  4. 4. How old are you?

  5. 5. How much have you considered spending?

  6. 6. Who you purchase them from.

There are basically two types of binoculars

Porro Prism

Roof Prism

Sleek & Straight - Light & Compact

but they produce a slightly dimmer image and are more expensive because of the precision required for assembly.

Good for wild life viewing; birds, animals etc.

Not the first choice for astronomy

Bulkier & Heavier than Roof Prism

but with high quality BAK-4 coating

will reflect more light to your eye resulting in brighter images than roof prisms.

They also cost less on average then roof prisms.

Porro prisms would be my first choice for astronomy.


COLOR of glass coatings.

    Look into objective end of the binoculars (the large end) and notice what color you see.

White - no coating

Blue - partial coating

Green - usually fully coated

Fully coated is best because it reflects more of the light through to your eye resulting in a brighter image.

Bottom line - Green is best

What is the best  SIZE?

7x50 seems the best choice to start with. “7” represent power and is enough to give you spectacular views over the naked eye. If you go over 10 power you may have to put your instrument on a tripod to steady the image.

“50” (the large end) will allow adequate light to enter the binoculars for you to see. When you go over 50 the instrument becomes much heavier and may need additional support.

10x50 may be your second purchase.

Good eye R E L I E F.

This is important if you wear glasses.

15 to 20mm eye relief is good.

Check with your seller for this information.

Orion binoculars offers retractable eye cups on many products. If you are the only family member that wears glasses, this option is an easy solution for sharing your instrument.

What about PRICE. $$$$$$$$

Good quality binoculars (7x50-10x50)will cost $150-250. Over a 10-20 year period, binoculars fitted to your specifications and of good quality will end up being a bargain.

Also, don’t forget to check for proper focusing, scratches and internal dust on the glass. This should not be a problem when buying new.

Check to see if the center hinge will adjust to the width of your eyes.

They should also have a socket for tripod mounting.

“Try before you buy is recommended”. If you haven’t a reputable vendor nearby, you can purchase by mail order or internet. Just remember to check their return policy.

If you have any questions, don’t hesitate to email me at...    l.wenzel@mchsi.com