Oct 29 2007
binoculars?
souper_nerd asked:
how do you know how powerful a set of binoculars is. What does like 8 x 21 mean? If the numbers go higher or lower does that mean it is weaker or more powerful?
how do you know how powerful a set of binoculars is. What does like 8 x 21 mean? If the numbers go higher or lower does that mean it is weaker or more powerful?
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6 responses so far
8 iis the magnification, 21 if the field of view at a certain distance.
I prefer a minimum of 10 magnification.
Also, you can get these in variable magnification, so you can zoom in close, or zoom back to see more area.
The first one is the power (magnification) and the second one the diameter of the lens in millimeter.
the higher numbers, the stronger the power of resolution. if you want some pretty cool binos, they now have ones that automatically focus.
It means that it has 8 times magnification and the 21 means the diameter size of the lens that collects light (the front glass on the binoculars). Hope that helps…
In a binocular (or spotting scope or rifle scope) the designation goes as follows:
magnification x diameter of the objective lens (the lens the light comes in) measured in mm.
8×21 is a binocular that magnifies 8 times and has objective lenses 21 mm in diameter.
7×50 would magnify less, but would gather far more light and be generally brighter.
10×42 would magnify more but would be more likely to have noticeable shakes as you hold them up – everyone has fine hand tremors and the higher the magnification, the more noticeable it is.
Magnification isn’t always good but is usually what is meant when the word power is used. The 8×21 is often called an 8 power binocular for instance.
The 8 refers to the magnification power. 8 says that the image will be magnified 8 times. The 21 refers to the diameter of the lens in front–the objective lens. It in this case would be 21 mm.
8 power is perhaps the most popular power for a binocular because that for many people is the highest power at which the image remains steady (not shakey) when viewed. 10 power is also popular because they are 25% more powerful and although the image may be slightly shakey for some people, it is not bad. 21 mm binoculars are compact binoculars, easy to carry around and pack in luggage. The advantage of having a larger objective lense is that it gives a brighter image (lets more light in). 50 mm binoculars are pretty large but still fairly portable but heavy. 40 mm binoculars are extremely popular because the are not too large and not too heavy but let in a significant amount of light. Star gazers sometimes use very large binoculars 20×100. They have to have a tripod to mount them on, but they are super for looking at comets.