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Examples: Ever heard of a fixed power scope? Sure you have. They are still the most superb for clarity, although not as well accepted as a few years ago. The standards were 6X42mm and 8x56mm. Fine European scopes, such as Kahles, Swarovski, Schmidt & Bender and Zeiss used these power ranges (and still do) for decades! Divide the mm (Lens diameter) by the power of the scope...Wallah: 7cms !!
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(side topic)
Funny how most scope manufacturers have gotten away from building fixed-power scopes. Of those that you listed, only S&B are still making them (in fixed flavor).
Not picking on high-end Euro scopes, domestic market is much the same way.
I prefer fixed power; less crap inside which means less weight and less likely to break when I need it the most.