Telescope Reviews: Re: What does the 'Visibility Index' tell you?

< "Magnification (Adler index) will have greater emphasis IF your targets are stars. Aperture and exit pupil will have greater emphasis if your targets are extended objects such as faint nebula and galaxies." >

Neoweb ,

I've copied and pasted the above paragraph , yet again , for a reason . EMPHASIS !

Although I must have read literally THOUSANDS of binocular reviews and articles about binoculars and binocular astronomy , Ed Zarenski is the ONLY person I know of to have presented such a wonderfully simple and accurate summarisation of " visibility index " -- which could even ( correct me if I'm wrong , Ed ! ) be a term created by EdZ himself .

In NO way do I intend to be critical or sarcastic here , neoweb , but in my humble opinion , it's such a valuable summary of the way things happen to be with binoculars , that to ask the question : ---

" My targets are galaxies, nebula AND star clusters.
So an emphasis on aperture? " ----

---- is ALMOST akin to NOT having understood the statement !

I'm sure Ed will answer in his own way , anyway , but the crux of the matter is that WE CAN'T HAVE IT ALL WAYS !

For what it's worth , my own opinion is that a GOOD 20 x 90 , in DARK SKIES , would be a better choice for YOUR trilateral requirements , than would , say , a 25 x 80 of equal quality .

Of course , I COULD be wrong ! :-)

Regards , Kenny

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If everyone is thinking the same thing , no-one is thinking - General George S.Patton

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