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Old 16-10-2007, 08:43 AM
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Satchmo (Mark)
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Join Date: Dec 2005
Location: Sydney
Posts: 1,858
If I can add there , the focus IPD thing with Crayfords is no issue, just a matter of always follwing the routine. Just rough focus each eye first. Then set you IPD , then touch up fine focus : the fine focus is maybe a few tenths of a mm so doesn't upset the IPD .

We had 6 people from Macarthur AS looking through Paul Shopiss' 12" binos , they were complete newbies and had no trouble with the adjustments.

A note on focal length differnece for bino mirrors. 2% differnce is the where the brain might start to not co-add images in stereo. I prefer to allow a figure of half that, consisting of 0.5% margin for eyepiece FL difference and 0.5% for mirrors. Which means ideally 6mm for a 50" focal length scope. Mirrors matched in production allow them to be much closer than that.
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