My Big Binocular Mount

[erick]

When I got my 20x80s, I realised that my Velbon tripod was not up to the job. Generally supported them OK, but couldn't get particularly high altitude before I got tangled up in the tripod and, worse still, a little wind and the image would jump around.

So I looked to see what I could buy - Gulp at the $US prices! Time to build my own.

Below is a shot of the mount dismantled, ready to pack in the car, and two shots set up - overall views.

(yes, they are not 20x80s but my new pair of 30x100s mounted - I couldn't resist.)

[h0ughy]

so how does it tilt?

[erick]

Here are a couple of close-ups of the fork mount itself. I decided not to have a vertical up/down motion at the tripod pivot point, nor an azimuth motion - adds complication and potential wobble points. I decided to live with azimuth and altitude at the binocular pivot point, and rely on the up/down of my gas lift chair to cope with the different hieght position of the eyepieces.

By having the fork mount come out at 45 deg, I can point the binoculars sort of close to the zenith without getting caught up in the mount. I do move the binoculars forward on the central mounting bar since my gas lift chair won't go low enough. Though they are then quite top heavy, the mount locks well in place.

[erick]

"Adopting the position!" Easy up to (whatever) degrees - I've set it up for me and my gas lift chair. Gas lift fully up - I'm looking a bit above the horizon. Smaller people - sit on a cushion! Taller people - not sure?

Drop the gas lift as I go up in altitude, tilt head and, eventually, lean back. The second shot was a quick one for the camera before it rainned (the grass shows we need it) so I hadn't adjusted the bins properly on the central mounting bar for that altitude.

(ps - book appointment with chiropractor for day after viewing at altitude.;) )

More details and "road test" next post.

[erick]

Parts list - rough :) .

Back of cupboard - old broken tripod that cost $20 in the 70s - rip the guts out of it and saw off the legs, leaving enough of the tubing to connect to some solid hardwood legs. Fit a solid hardwood platform and vertical bolt to mount transverse arm (the only piece of pine in the project).

Chair graveyard (at my work) - broken gas lift chairs as long as gas lift working, and a few extra knobs with embedded nuts.

Out the back of the lawnmower shop near the dumpmaster - few more threaded knobs from the handle fold position of old lawnmowers.

Recycling bin - a few milk bottles from which to cut out the "friction bearings".

Hardware store - various bits of wood, screws, bolts etc, couple of strong metal brackets.

Local fitness world store - some weights (go back next day and swap the 2.5kg for a second 5kg when you observe your first calculation was a bit of an underestimate!)

Construction :)

Design as you go! Use lots of big strong screws and bolts. Cross fingers that the guts of a lightweight aluminium tripod will hold up some 20 Kg! (It does - I'm careful to fully extend the tripod legs to leave no slack in the mount.)

Ignore some basic problems like when you mount the two brackets together, the already drilled holes no longer line up horizontally - if necessary, tilt the binoculars on the central mounting bar to compensate! Mind you, even picking the best bit of pine I could for the transverse, it still had a small twist in it.

"Test Drive" next post.

[erick]

"Test Drive"

I've had it out once in the car - last Friday night all the way to Snake Valley to try Ken's dark skies. Have set it up a few times in the back yard. One evening and once for the photos today.

Yes, it's not super robust - If you dropped the tripod or vigorously twisted it, I expect the aluminium mechanism would crack - but I can treat it with care.

Easy to set up - couple of minutes and it's ready to accept the binoculars - but I'll probably keep a pocket full of spare washers and PTFE "friction bearings" - I can see myself dropping one or two in the dark one day.

(In the photos, you'll notice a extra block of wood at the binoculars mount point. I'd seen this problem highlighted before - when the bins are at their balance point, the central mounting bar is too short. I know there is a spacer available and I may buy it yet - at the moment the block of wood is doing the job, also it stops the 1/2 inch bolt from falling out when I disconnect the binoculars and I'm more concerned with placing them safely than I am about some 30 cent bolt falling on the ground.)

When all set up, I have only four movements available to me:-

* Azimuth at the binocular mount point
* Altitude at the fork mount
* Slide back forth at the binocular central mounting bar
* Follow the eyepiences up/down and in a semicircle on my gas lift chair (I've kept the wheels on the chair - which will probably be hopeless when the ground gets soft.:( )

So I spent three hours at Snake Valley testing it out two nights ago. I was thrilled with the performance of both the mount and the 30x100 bins (which arrived Thursday!). I was able to easily set the "friction bearings" to allow me to adjust the binoculars to the desired view and have them stay there (up to a reasonable altitude - eg. Crux and Carina area and the Moon - no problem up to midnight). I was able to find a comfortable way to set up on higher altitude objects and study them for a good period of time. I just adjust the binoculars forward on the central mounting bar, lock the altitude friction bearings some more, drop my seat right down, slide forward under the transverse bar, hold onto my legs and lean back a bit. I was able to look at M42, LMC, 47 Tuc quite comfortably for minutes. I am going to experiment with a chair I've bought that supports my head back to almost horizontal, but my eyes are them well below the eyepiences - I'll think about a solution.

Now the bump test! There was some wind and I noticed that I did not see the jittery movement I had with the 20x80s on a Velbon tripod (where this story started!). So I tapped the mount and observed that the movement very quickly became a slow rock - nothing that was a problem given the FOV of the binoculars. In fact, it would die within 7-8 seconds. When the wind came up again, a gentle sway was all that I could observe and I can live with that.

I've a couple dew shields to come - the paint was drying in the garage when I took the photographs. Am I the only person who goes supermarket shopping with a set of calipers? I found some cylindrical dog food containers that were close enough and could be modified to slide over the binoculars with a bit of the loop part of velcro in place as the seal - in fact the containers had plastic end caps that I've kept and can place over the ends of the dew shields if I'm going to not observe for a while. (Dog food went into the bin - sorry - no dogs here.)

If you've read this far - well done!

I'll report any failures/collapses if they happen!

Now to spend a year learning the sky with my binoculars - using my 12x60s handheld or on the Velbon tripod, and my 30x100s on this mount.

Thanks
Eric

[ballaratdragons]

Wow Eric, Sterling job on the mount!!!

You are certainly a man with a great talent of using trash, just the way I like it.

Trash is great for making stuff.

Excellent write up and explanations on all subjects. Wish I knew you were up at our SVAA observing spot though, I wouldv'e joined you, but the 19th is approaching :thumbsup:

[erick]

Only at the fork, Houghy. I debated adding a see-saw and rotation at the top of the tripod and figured 1) too complicated and 2) it would probably wobble all over the place. :)