|
|
What should I look for?
Home » Astronomy » Binoculars » What should I look for?Now that you’re ready to look at binoculars, what will be the first pair you pick up? That’s right. The porro prism model. They are easy to tell from their zig-zag, old-fashioned shape. If they are compact, designed side-by-side, or look like a little box, put them down. What suits a bird-watcher or a hunter does not suit an astronomer.
Ask to examine the binoculars. The correct ones will be hinged in the middle to allow you to adjust for your eye width. While some models may have both the right and left lens adjustment, they must at least have a right diopter—meaning the right lens can be adjusted for your right eye independent of the central focus. Closing your left eye, adjust the right diopter until a distant object is in focus. Then open both eyes and use the central focus to bring everything sharp. If you see a double image, an outline of color, have to press your eyes against the lenses or cannot bring a distant point to clean focus—these are not for you.
When you have found a suitable pair, examine the lenses in the light. White reflections mean poorly coated optics while dark appearing, or green to purple reflections are the most desired. Now hold them at a distance and look down at the eyepieces. Are both fields evenly illuminated? If the edges are squared off, they may have a low quality prism. Holding them to your eyes, pass your hand first in front of one lens—then the other. If the image seems to switch locations, these binoculars are out of collimation—a serious defect.
If they pass these simple tests, regardless of expense, these are worthy “twin telescopes.”
Related Binoculars Articles
- Choosing Binoculars
- Are all binoculars made the same?
- What type of binoculars is best for astronomy?
- Where should I buy binoculars?
- What should I look for?
- What size and power are best for me?