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Equipment Discussions >> Binoculars

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ronharper
Carpal Tunnel
*****

Reged: 02/14/06

Re: 127mm f/5.5 binocular new [Re: Mr. Bill]
      #5618336 - 01/12/13 12:55 AM

That is awesome Mr. Bill. An original and versatile design, and nice work. Your talent and the thing itself are both enviable.
Ron


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planetmalc
sage


Reged: 10/21/09

Re: 127mm f/5.5 binocular new [Re: Rich V.]
      #5618837 - 01/12/13 11:18 AM

Quote:

I understand your point, Planetmalc, keeping the eyepieces near and in line with the alt axis limits the viewer's movement for a single eyepiece but with the BinoBox it seems fiddly to have to keep re-setting the diagonals to maintain a relatively level viewing position and still achieve proper IPD from low to high viewing angles.

You've essentially changed the neck motion from up/down to right/left lean. To keep the right/left lean minimal, you'd have to be adjusting the swing of the diagonals frequently.




Rich: when I modelled it in cardboard - the ONLY way to see what's really going on - I joined the centres of the 'eyepieces' together with a tie-bar and drawing pins, with the distance between the two drawing pins being equal to my IPD. The two cardboard 'diagonal arms' then swing as a single unit with the IPD being maintained, and the process seems completely natural because there's only one possible position the unit can be swung to if you want the eyepieces to end up precisely horizontal (not a necessity of course, but probably the orientation that most observers would go for). This is obviously simpler than adjusting the relative positions of two real diagonal arms on a real instument, but if I was making a binocular like this - and I just might - then I'd probably try to fashion some kind of tie-bar on the actual instrument itself (shaped like a o--o, with the ring-shaped bits around an exposed section of the 1.25" tubes that slide into the focuser). It might eventually prove not to work, but I'd sure try it! The big problem that I forsee would be the one that Mr. Bill encountered: insufficient friction in the pivoting bits. I could use Mr. Bill's remedy, but there'd be so much more diagonal arm-swinging in my system that I think this particular area might require frequent maintenance.

The amount of vertical/horizontal head movement required to compensate for changes in declination can be reduced to a minimum by attaching the bino-box to the mount at an optimum point that needs to be determined by pre-modelling in cardboard - it is NOT where you'd intuitively expect it to be!

Quote:

For many of us, I think, the familiar up/down orientation of the sky in binoculars (even if L/R reversed in this case) makes moving the bino or scope towards a target more intuitive. YMMV, of course.




I agree entirely, but I think I'd eventually get used to the bottom-mounted system (and if I couldn't, I could always convert it to side-mount). The type of finder used could be crucial here: I think I'd want a correct-orientation image, so I'd probably have to have (say) a low-power rifle scope with its long eye-relief allowing the use of a small pentaprism between scope & eye. Annoyingly, this would completely go against the concept of minimal head movement.

Edited by planetmalc (01/12/13 12:31 PM)


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GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: 127mm f/5.5 binocular new [Re: planetmalc]
      #5619609 - 01/12/13 06:33 PM

I've just sketched out the geometry of the independently rotating eyepiece assemblies, and can see that in principle one should be able to devise a scheme which will allow to keep the eyepieces oriented horizontally as the bino is swung in altitude while 'lying on its side.'

This arrangement requires that the mechanical dimensions be such that the swinging arms do not interfere with each other, and at first examination may make it difficult to build for the 2" eyepiece format. This also seems to require a relatively close observance of the ratio of objective separation to radius of swing of the eyepieces.

When the altitude axis coincides with the middle of the eyepiece pair's range of motion, the required vertical head movement is quite minimal. To get the pivot point moved rearward to the required degree and regain balance, it requires only to have a counterweight on a bar extending rearward, as part of the mount, said bar doubling as a handle.

An idea which has merit!


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planetmalc
sage


Reged: 10/21/09

Re: 127mm f/5.5 binocular new [Re: GlennLeDrew]
      #5622483 - 01/14/13 11:17 AM

Quote:

I've just sketched out the geometry of the independently rotating eyepiece assemblies, and can see that in principle one should be able to devise a scheme which will allow to keep the eyepieces oriented horizontally as the bino is swung in altitude while 'lying on its side.'




I'm impressed; I had to build a life-size cardboard model to figure all this out!


Quote:

This arrangement requires that the mechanical dimensions be such that the swinging arms do not interfere with each other, and at first examination may make it difficult to build for the 2" eyepiece format. This also seems to require a relatively close observance of the ratio of objective separation to radius of swing of the eyepieces.




Indeed. Even the footprint of the splendid Stellarvue 1.25" units that Mr. Bill has used might be too much for observers with narrow IPD's - it's those protruding corners that cause all the trouble. There's no doubt that people who have widely-spaced eyes could be much more cavalier in their choice of the 3rd diagonal. Someone, somewhere makes a 2" diagonal with a circular - rather than square - footprint, but I can't remember the name of the brand. A bit of serendipity might be all that's needed to make their use feasible.




Edited by planetmalc (01/16/13 12:00 PM)


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