Telescope Reviews: Re: Is aperture king? Does aperture rule?

Thank you very much to EdZ for a great reply! And to the others who have replied thoughtfully in the spirit of the serious question - about BINOCULARS (not telescopes).

If it's necessary in order to move away from monarchy jokes, we can rephrase it "Is aperture everything?" or "Is aperture the be all and end all?", or something like that. (I used the subject that I did because I've seen it written both ways recently, here and elsewhere - not because I'm concerned, or not, about monarchism.)

After reading various forums about and comparisons of binoculars for at least five or six years now, I find it hard to believe that - in relation to BINOCULARS - people still repeat, mantra-like, "Ommmm. Aperture. Ommmm." (The same would go for magnification alone, by itself.)

If you are young and observe from dark sites and want to see low-contrast objects, then definitely you can benefit from larger exit pupils (more aperture per unit of magnification - given equal optical quality otherwise), so an 8x56 would be better than 8x40 - under those conditions. But at least a third to a half of every month the sky is not dark due to moonlight. Many observers are not young. People who observe from cities and suburbs don't have dark skies. Some people usually observe variable and/or multiple stars and star clusters more than faint fuzzies (not to mention birds, butterflies, etc.).

Under all of those conditions, and given the extra weight of the larger objectives, etc., there's little to gain from the larger exit pupil (more aperture per unit of magnification) - when talking about BINOCULARS.

The reason they put both magnification and aperture on the BINOCULARS is because they BOTH matter! So the Adler and Bishop and Ed Zarenski performance measurements that take both aperture and magnification into account are all very much better than a simplistic unthinking myth that takes only one of the two specifications and throws the other one away.

If you are advising someone asking "What binocular should I buy?" all of the following questions are important:

1. What do you want to see?
2. For astronomy, how dark is your observing site?
3. Will you be using the binocular handheld?
4. Will you be observing with eyeglasses on (even just sunglasses in daylight)?
5. What is your budget? Are you sure you can't spend more, in order to get higher quality?

What questions did I omit...?

It seems to me that if there's any single valid rule of thumb for choosing BINOCULARS, it's "fully multicoated". That's not a bad mantra (although it's no guarantee).
But beyond that, the other questions above always need to be considered.

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Ed Cannon - Austin, Texas, USA

As of 23 August 2008 - Celestron Skymaster 12x60

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