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127mm f/5.5 binocular

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#176 planetmalc

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Posted 11 January 2013 - 12:23 PM

I don't see this as possible at all... I take it you mean the bino is now oriented such that when pointed toward the horizon, one objective lies directly above the other, effectively having the instrument lying on what would currently be considered the side.

Exactly (and firstly, may I apologise for leaving the word 'sideways' in my original post; it should have been edited out).

Starfields don't have a 'proper orientation' (if so, they'd be 'upside down' in an absolute sense in the southern hemisphere) so it matters not a jot what their actual orientation is when you observe them - OK, it might be unfamiliar, and require star atlases to be rotated, but it wouldn't be 'wrong'. I accept that it seems less 'right' to do this with a binocular than it does with a telescope because we normally use bins with their OG's parallel to the horizon, but whilst this is a necessity in terrestrial use it is irrelevant for astronomy (asymmetric binoculars are an example of this).

There can't be many knowledgable 'scope users who haven't thought, "I'd love a Springfield mount", because having the fixed observing position is just SO convenient, but they're complicated and probably not compatible with low magnification/wide field aspirations. Designing a Springfield-mount binocular would be a nightmare, but if you use large bins and want your observing position to be as static as possible - and are prepared to compromise by accepting that you could enjoy a 'Springfield effect' for objects at ANY declination, but ONLY across a small-ish range of RA - then surely this would be worth going for. I envisage a seated observer, using a bottom-mounted Mr. Bill design, sitting side-on to whatever he is observing (we already do this with Newtonian telescopes), with his head ALWAYS held in its natural position (upright and with the eyes looking parallel to the ground), observing an object at ANY declination through an arc of 180 degrees, with only small movements of the head being required to compensate for changes in declination. As I said in my original post, if the (principal axes of the) OG's are around 9" apart, and the instrument is bottom-mounted, and the 1.25" diagonals have a small footprint, then for diagonals arms whose diagonals have their centres 4.5" apart (as per Mr Bill's layout in post #1), it is ALWAYS possible to orient the diagonal arms so that horizontally-aligned eyepieces are presented to the observer with the correct IPD (you really have to make a life-size scale model of the system to see the complex geometry that's going on when you swing the diagonal arms around - it's not something you can visualize). The eyepiece position (compared to a fixed datum) DOES move a little (both vertically and horizontally) for changes in declination, but can be compensated for - even if the observer is seated in a fixed-height chair - by slight changes in posture. The observer only ever needs to significantly alter the position of his head when he gets up to move his seat so that he can observe another object which has an appreciably different RA.

If you think about it, when forum members are discussing the relative merits of straight-through, 45-degree or 90-degree eyepiece inclinations (and bemoaning the fact that the preferred 90-degree option usually comes with reduced-aperture problems) then we're really talking about keeping head position as natural as possible, to reduce fatigue; the bottom-mounted Mr. Bill instrument achieves this and all the design work has been done.

#177 planetmalc

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Posted 11 January 2013 - 12:30 PM

The alternate position for positioning the diagonals puts eps much closer to the altitude axis so the swing from horizon to zenith is minimized.

I tried both and prefer the diagonals and ep further back as I generally observe standing and don't like leaning over the binos...

Leaning is NEVER required if you use the bottom-mounted system, Bill.

#178 Rich V.

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Posted 11 January 2013 - 01:20 PM

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.

Unless I had a real neck mobility issue, the standard alt/az orientation with 90° viewing is pretty comfortable for me, whether it's an angled bino or a telescope/diagonal.

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.

Rich

#179 Gordon Rayner

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Posted 11 January 2013 - 07:39 PM

Looking at Mr. Bill's picture of his mount, above, gave the following construction insight(?) , unrelated to the mount motions:

A "D" size long dovetail pair from ADM, or Losmandy, or other suppliers of mounting quick-release dovetails, could be milled and/or bored and/or bandsawn and then hand filed, to have a large racetrack shaped, or rectangular, opening. This would be the basis for a linear IPD motion of one 2-mirror "prism", to gain an erect image with only two mirrors.

One roof mirror "prism" , fixed to a segment of dovetail, either male or female,would move laterally on a much longer piece of dovetail of the opposite gender. Another segment would hold the other "prism", which would have no lateral IPD motion. It would be fed via a circular or square opening near the racetrack shaped opening.

The eyepiece fed by the moving "prism" would be moved laterally by twice the lateral motion of its "prism". The motions could be 2:1 linked, as in WW II Zeiss 25 x 100 or 12 x 60, 25 &40 x 200, and others, for real-time synchronization.

Or, the 2:1 motion could be set by an observer who is the usual, or only, user, without linkage, to simplify construction.

ADDENDUM 1/13/13 :

Two ADM DUP7M, or comparable offerings from others, bolted together back-to-back ( available bolted from ADM), would form the structural core. The lower, inner DUP7, facing the inside of the box body, would hold each of the roof mirror pair "prisms", one of which would be laterally slidable .

The upper, outside the box DUP7 would hold the female eyepiece carriers, one of which would be laterally movable .

Suitable openings would be made as described.

#180 Mr. Bill

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Posted 11 January 2013 - 07:49 PM

Hey Gordon

I did this with a radial arm saw and a floor drillpress....

if I had a machine shop I could have been more inventive.

:cool:

#181 ronharper

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Posted 12 January 2013 - 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

#182 planetmalc

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Posted 12 January 2013 - 11:18 AM

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!

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.

#183 GlennLeDrew

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Posted 12 January 2013 - 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!

#184 planetmalc

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Posted 14 January 2013 - 11:17 AM

[quote name="GlennLeDrew"]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.'[/quote]

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.[/quote]

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.[/quote]






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