At least twice in different threads, the following topic has come up: It was stated that 7x binoculars are particularly bright because they have one lens element less than 8x models. I'd like to know why this is possible and whether this holds for all brands and objective diameters.
As a second question then, I wonder whether higher magnifications like 10x or 12x need even more lenses than 8x models. And if not, why is the 7x an exception (if it really is one)?
[QUOTE=Swissboy]At least twice in different threads, the following topic has come up: It was stated that 7x binoculars are particularly bright because they have one lens element less than 8x models. I'd like to know why this is possible and whether this holds for all brands and objective diameters.
As a second question then, I wonder whether higher magnifications like 10x or 12x need even more lenses than 8x models. And if not, why is the 7x an exception (if it really is one)?[/QUOTE]
There is no reason the eyepiece of an 8x (or a 10x) binocular needs more elements than a 7x pair. There may, however, be a correlation between apparent field and how many elements are in the eyepiece. In the world of astronomy you pay a premium for eyepieces with large apparent fields for a simple reason - you need to do more work to get good images at the edge of a wider field, and this means a more complex design with more elements.
With modern coatings, which are very effective, and glasses, which are very transparent across the spectrum, one or two elements more or less is unlikely to make enough of a difference to be perceived.
Clear skies, Alan