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Message: <blockquote data-quote="Omid" data-source="post: 3392901" data-attributes="member: 16724">Very well said. I am a hunter and I fully agree with your comments. Now, this is a bid watching forum so lets go back to the topic of zoom binoculars. Zoom is a very useful feature in binoculars but it is very hard to provide for several technical reasons. On the other hand, zoom is not the most desirable feature in a rifle scope (which is an "aiming device" not an observation device) but it has been included in rifle-scopes and it has been pushed to insane extremes (Swarovski just introduced their 8X zoom-ratio scopes in IWA this March). The reason riflescopes have zoom is because it is easy to do: Rifle scopes (mostly) use lens based erector systems. This makes it very easy to provide zoom: the erector lenses are moved back and forth in a coordinated way and this changes magnification.There are two main reasons that making zoom binoculars is very difficult:a) Binoculars use prism erectors and the only way to make zoom is to make some of the eyepiece lens elements movable. This doesn't provide much zoom (1.5X to 2X at best) and correcting optical aberrations are also difficult.b) The second, and perhaps more challenging, problem is that both barrels should provide exactly the same magnification during zoom and this is not easy to achieve. Even a very small magnification mismatch (or alignment mismatch) can cause eyestrain and headache. That's why Leica made their Duovid binoculars 8+12X42 not 8-12X42. I have a pair and they are great. You can see me wearing them on my website:<a href="http://www.omidjahromi.com" target="_blank">www.omidjahromi.com</a>Cheers,-Omid</blockquote>

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