Thanks to the experienced oldtimers writing here and on CN over a decade, I wrote out the following 'list' in 2019:
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Considerations when choosing your binoculars
1. Ergonomics:
Are you able to hold it comfortably?
Will you be able to carry it in your environment?
Feel for
- weight in your hands and on your neck
- the shape of barrels
- balance
- armouring
- focuser position
Does it fit to your eyes & nose comfortably?
Feel the eyepiece contact, check for sufficient ER & IPD
Build quality:
Are the hinge, the focuser, the dioptre mechanism all easy to adjust? (fast enough)
Are they smooth, light, exact?
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2. Optics:
Do you find the view comfortable?
Look for
- Low or no visible aberrations
- Three-dimensionality of image (not a flat poster)
- Window view (not a tunnel)
- Close focus comfort on the eyes (parallax effects)
- Little or no apparent purple fringing (low CA)
- Veiling glare, minimal over water or near low sun
- Good microcontrast & colour, especially the middle area
- Brightness (buy something over £500)
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3. Overview:
Does the instrument seem to vanish in use?
Does it feel easy & natural like looking through a window?
If it feels awkward in your hands, against your face, or if the image displeases, try another.
Binoculars always compromise
- user wants & needs versus their physical abilities
- manufacturer designs versus size & weight & cost
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Again, my thanks to all the experts who share.