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 Post subject: Celestron big (25x100) binoculars
PostPosted: Fri Oct 30, 2009 12:43 pm 
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Joined: Mon Oct 12, 2009 6:47 pm
Posts: 1268
Location: Bolton
Yes, these are big: 25x magnification and 4" diameter object-lenses.

The problem is keeping them steady when looking up at the sky: I solved this with my home-made double-sided version of the "parallel-motion" mount.
Attachment:
File comment: The binoculars fitted to my home-made parallel-motion mount.
The cardboard tubes on the ends are home-made "dew-caps", to slow the rate of condensation on cold damp nights.
One of my colleagues at work came up with a great caption for this picture: "should have gone to Spec-Savers!" :-)

binoculars.jpg
binoculars.jpg [ 60.01 KiB | Viewed 3188 times ]

This is very useful at star-parties (I've taken it to Kelling Heath three times), since it can be adjusted to suit the different viewers' heights without losing the target.

Their field of view is 3 degrees, so from a dark-sky site the view of larger objects (such as the Double Cluster) is fantastic, and they are also great for "Messier marathon" events and comet-spotting. There is some colour-fringing on very bright objects, and "coma" towards the edge of the field, but remember that these are not very expensive APO optics.

And they share the advantage of all binoculars in that they can be used for terrestrial observing too, so long as you're not aiming them up in the sky then a standard camera tripod is all you need as a support.


Last edited by rwilkinson on Fri Oct 30, 2009 12:45 pm, edited 1 time in total.
added note to caption


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