BirdForum is the net's largest birding community dedicated to wild birds and birding, and is absolutely FREE!

Register for an account to take part in lively discussions in the forum, post your pictures in the gallery and more.

Reply to thread

Message: <blockquote data-quote="Kevin Purcell" data-source="post: 1563031" data-attributes="member: 68323">I think about 1 turn from close focus to infinity with over and under-run for hyperopes and myopes. But the usable range from 6 feet to infinity in 1 to 1.25 turn would be about right. Try out some binoculars to see what your team thinks. I think faster but not too fast is better.The other consideration is how the focus rate is distributed over the rotation e.g. it shouldn't get excessively slow at close focus. Most passarine birding is done between 3m and 40m with the rest at infinity (bigger birds).Another consideration is focuser tension in addition to focus rate. Both contribute to the perceived focus speed. Having a fast rate and high tension doesn't feel faster. A fast rate and low tension can feel fiddly and prone to overshoot. A slow rate or high tension can make it difficult to track birds. Finding the balance is critical: some sort of medium rate and medium tension. User testing for this is critical.Zoom bins have a terrible reputation for weight, poor transmission and lack of FOV. To be interesting you would have to overcome those problems and I'm not sure you can do that with a zoom bin. I'd be curious about a "switch power" 7x and 12x with good FOV and ED glass would be very interesting. Both Leica and Leupold have one in their collection. But you need a decent FOV at the low power.8x is most common. Some (including me) like 7x. 10x is still popular with some.</blockquote>

Verification