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127mm f/5.5 binocular

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#26 mercedes_sl1970

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Posted 27 June 2012 - 07:39 AM

Looking forward to following the build of these binos. Should be fascinating.

Andrew

#27 Mr. Bill

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Posted 27 June 2012 - 04:22 PM

Finished layout...cut box pieces out of cabinet grade birch plywood.

:cool:

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  • 5291920-Box pieces cut.JPG


#28 Mr. Bill

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Posted 27 June 2012 - 04:41 PM

Diagonals (99% dielectric) and low profile helical focuser with 1 3/4 inch travel....

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  • 5291961-diagonals+helical focuser.JPG


#29 Mr. Bill

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Posted 28 June 2012 - 02:57 PM

Box assembled and waiting for parts...

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#30 Rich V.

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Posted 28 June 2012 - 03:12 PM

Moving along nicely, Bill!

:D

Rich

#31 Mr. Bill

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Posted 28 June 2012 - 03:22 PM

Yeah Rich....

I'm getting better at this box building after the 6 inch f/5 EE Barnard box considering the *BLEEP* radial arm saw I have.

The rail apparently has a slight amount of roll in it over full travel.

"Good enough for government work"....(I should know)

:grin:

#32 Andresin150

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Posted 28 June 2012 - 04:05 PM

looks promising! :waytogo: :waytogo:

#33 GlennLeDrew

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Posted 28 June 2012 - 04:35 PM

A suggestion. Place a thin-walled divider between the two optical paths so as to ensure no light leakage through one objective onward to the opposite eyepiece. It may not be necessary--especially so if the optical path length from first mirror to focus is long--but it never hurts.

This is looking rather reminiscent of my first 5" build, of which I will eventually post photos, both of the outside and the innards. (But I made use of black anodized aluminum plates for both the objective cell and focuser/mirror system supports.)

#34 Mr. Bill

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Posted 28 June 2012 - 05:55 PM

Thanks Glenn...wow, that's weird. I was JUST thinking about a divider between the objectives.

Will do.

:cool:

#35 marcelof

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Posted 28 June 2012 - 08:32 PM

It is the style box!!! I understand that to use pipes of aluminium would complicate the things and to raise the costs. We wait anxious for the results!!
Good luck! :jump:

#36 Mr. Bill

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Posted 29 June 2012 - 11:33 AM

Box with divider on mount...

Secondary holders on truck for delivery, according to UPS tracking so I will be able to put together at least one side to check out this weekend.

3.1 mirror and flocking material (the last of parts ordered) should show up today or tomorrow....

Got my fingers crossed that I got it right on paper...

:cool:

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#37 Mr. Bill

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Posted 29 June 2012 - 08:39 PM

First light with one side....other 3.1 mirror hasn't arrived...maybe tomorrow.

Collimation appears to be fairly straightforward (at least for one barrel.)

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  • 5295549-first light with binoscope.JPG


#38 Mr. Bill

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Posted 29 June 2012 - 09:10 PM

Once I shorten long adjustment knobs, I can move diagonal back another inch and push components back further into lightcone, increasing edge of field illumination even more (about 60-70% now) Like to get 80% which I think is very doable.

I'll still have a couple of inches for hinged trapdoor in rear to tweak adjustments.

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  • 5295596-inside box.JPG


#39 Rich V.

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Posted 29 June 2012 - 10:10 PM

Looking great, Bill. What is the minimum IPD as shown in the photo above when the diagonals meet?

Any sign of sag in the diagonal/focuser train?

The Bino Box lives! :waytogo:

Rich

#40 Mr. Bill

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Posted 29 June 2012 - 10:23 PM

Minimum IPD as shown around 65mm (can get less by offsetting)...mine is 67mm. I probably could have increased objective spacing, but things worked out OK. Whew!!

Optical train looks very robust....still lots of tweaking but looks like everything will work out.

That's a relief after spending $2K betting on paper raytrace.

:p

#41 Smithfr2000

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Posted 30 June 2012 - 05:29 AM

Very interesting work ! Well done !

I do not understand how you achieve collimation with knobs inside the box ? Any explication ?
Thanks a lot.

#42 GlennLeDrew

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Posted 30 June 2012 - 10:54 AM

What's the weight? My 1996 version of the 5" weighed 27 pounds, and I want to shave a fair bit off the 2012 re-do.

#43 Mr. Bill

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Posted 30 June 2012 - 01:00 PM

Looks like just under 30 pounds, Glenn.

#44 Mr. Bill

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Posted 30 June 2012 - 07:11 PM

Received second 3.1 mirror by priority mail today.

Achieved near perfect binocular collimation centering a telephone pole 1 mile distant while maintaining reasonable intrabarrel collimation.

Once figured out what I was doing it was easy and alignments very robust.

Next step, star test.

Focusers work perfect in position shown and will result in very little change in position during altitude rotation. Should be able to sit and sweep from horizon to zenith without much if any seat adjustment.

Note: found helical threading to be too sloppy to precise maintain collimation alignment....used Teflon pipe tape on drawtube to provide stiffness and friction without stiction.

:jump:

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  • 5296894-first light binocular vision.JPG


#45 Mr. Bill

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Posted 30 June 2012 - 10:22 PM

Another interesting thing now that collimation is achieved is there is a 3-4mm difference in ep height when fine focused with the same eye.

I assume that is the difference in focal length between objectives.

That's around 1/2% so I guess that's probably normal.

I could put a shim on the long barrel to even out the ep height.

#46 Mr. Bill

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Posted 01 July 2012 - 09:39 AM

First light this morning between moonset and first light of dawn (3:00-4:00 AM)

"My God, it's full of stars."

This is going to be the "killer app" of Milky Way cruising machines. Panoptic 19 seems to be a perfect match for this...37x and 3.5mm exit pupil.

Much more to do...flocking, staining, varnishing but optical design proved.

Contrast even without flocking is excellent and dark nebulae and starclouds are breathtaking...even better than my trusty BT100s.

Maybe someday I'll be able to compare side by side with the Fuji 25x100s.

Total cost without eyepieces was around $2200.

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  • 5297647-first light.JPG


#47 marcelof

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Posted 01 July 2012 - 10:20 AM

That advantages has this disposition versus place only four diagonals going out on the later part?
(Besides saving both biggest mirrors.) :question:
Anyhow remain the eyepieces vertical to up, achieving the 90 º of inclination so looked.

#48 Rich V.

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Posted 01 July 2012 - 10:48 AM

Marcelo, if I understand you correctly, using two diagonals attached to the rear of the box so as to allow 90° viewing would present images 180° rotated relative to each other. One side would have the image rotated right 90° and the other side rotated left 90°.

Using the larger first mirrors to orient the images 90° initially allows the two diagonals on each side to mimic a rhomb which creates no rotational error as they are turned for IPD adjustment.

Rich

#49 GlennLeDrew

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Posted 01 July 2012 - 11:15 AM

I knew you'd succeed, Bill! And talk about short order, too--it came together mighty quickly. I'm not surprised to see that even non-blackened, the contrast is good. This is due in part to the fact that unlike a 'streamlined' bino, wherein the main tubes closely follow the converging light cone and thus too easily allow scattered light to do harm, your box has its walls, for the most part, well removed from the image-forming light cone. And the self-shadowing provided by the back side of the front board and lens cells is a big contributor, too.

Making your own binocular isn't so hard, is it? The very first astro instrument I built was a 5" bino, too. If one gets over the needless fear of super precision being required, it's not much harder than designing a Dobsonian scope.

#50 Mr. Bill

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Posted 01 July 2012 - 01:35 PM

I knew you'd succeed, Bill! And talk about short order, too--it came together mighty quickly. I'm not surprised to see that even non-blackened, the contrast is good. This is due in part to the fact that unlike a 'streamlined' bino, wherein the main tubes closely follow the converging light cone and thus too easily allow scattered light to do harm, your box has its walls, for the most part, well removed from the image-forming light cone. And the self-shadowing provided by the back side of the front board and lens cells is a big contributor, too.

Making your own binocular isn't so hard, is it? The very first astro instrument I built was a 5" bino, too. If one gets over the needless fear of super precision being required, it's not much harder than designing a Dobsonian scope.


That's about right....

Preparation before cutting pieces is essential. Raytracing and measuring backfocus of components like diagonals will prevent surprises.

Making the box refractor before this allowed me to hone up my woodworking skills but one slip and.... :o

This was done using only a radial arm saw and floor drill press. I would not attempt this project without them; the precision of cuts is beyond hand tools and Skil saws.

Taking a break today from project...my 80 trees are hollering for a deep watering!

:p

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  • 5298010-circle cutter setup.JPG



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