Quote:
Originally Posted by chris lewis
Sorry that is very incorrect. The optical qualities required for astronomical use are generally greater then those for terrestrial use. 'Cheap' binococular's do not work for astronomical use. Distortions and aberrations will soon show up. Stars need to be pin point with no secondary reflections or flareing esp. on bright objects. There needs to be minimal curvature of field. Collimation needs to be exact. Those qualities are not found in cheap or entry level binos.
Cheap binoculars do work for astro or birding use. It is best to get as high quality bino if you can.
Chris
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Fair enough, but my personal experience is that colour fringing, a bane of cheaper binoculars, is not very evident when using bins for astronomy. On the other hand when using them for birding it can be extremely annoying, particularly when a bird is silhouetted against the sky. Also poor focussing is less annoying for astro use as well, because you typically only focus them occasionally and don't have to keep changing focus. Finally, for casual use I don't think field curvature is too much of a problem either due to the large field of view, but I'm sure that with serious use it would be.
However, it was in fact astro use that showed the collimation to be out on an older pair of my bins, the double star effect was much more obvious than the more general blurring during the day. So I certainly wouldn't disagree with you there. However, I've generally found collimation to be fine on new bins, even those at the $100 level.
Horses for courses, but personally I'd be happy with $200 bins from AoE or the like for casual astronomy use, but can't stand that type of binocular for daytime use (birdwatching) - and I'm not talking just from the experience of the bins I currently own.
Anyhow, your advice to get the best binoculars you can afford is always correct!