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"Build a binocular mirror mount" in November '14 Sky at Night magazine

trynda1701

By trynda1701
in Discussions - Binoculars

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BinocularSky

BinocularSky

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The A4 size first surface mirrors from old style Xerox photocopiers made excellent mirror mounts for binoculars.  :smiley:

When did you last see one of those, Peter? The last discarded photocopier that I plundered for bits (sometime in the last century :laugh: ) had mirrors that were only about 2" wide; I was most disappointed.

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Peter Drew

Peter Drew

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As far back as only I, you and a few others can remember :grin: , many years ago I bought a job lot of these mirrors, 20 I think at £1 each, I've used them over the years for Camera Obscura mirrors but never a binocular mirror, I think I have a couple left so maybe one day.  :smiley: 

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trynda1701

trynda1701

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Sounds like a great idea....

I found a front surface mirror of suitable size and acceptable accuracy very difficult to find. Then protecting the mirror from dew became a show stopper.

Hmmm, I suppose that's a problem here in the UK indeed.

Anyone used one of these style mounts reguarly in the UK. On a typical night, how much use do you get before it dews up? I know you could just use a hairdryer to demist the mirror, but has anyone tried another solution? Heater strips for example?

Mark

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Sporadic Dobstronomer

Sporadic Dobstronomer

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I have not seen the design but I've made one of my own.  However it is still early days so I can't comment on dewing.

Mine has separate main mirrors which makes finding suitable items a lot easier.  They don't need to be coplanar as long as they can be adjusted to be parallel.  There is a third mirror so I can aim it with a laser pointer.

It is not finished but here is a picture.  There have been some developments since it was taken.

post-39514-0-78851600-1415373694_thumb.j

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MAN or ASTROMAN

MAN or ASTROMAN

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Sounds like a great idea....

I found a front surface mirror of suitable size and acceptable accuracy very difficult to find. Then protecting the mirror from dew became a show stopper.

 This fellow lives in Belgium,where the climate is much the same as ours (unless you live in the Highlands),and seems to do o.k. http//rodelaet.xtreemhost.com/binocular_astronomy.html. I really like his sketches.
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Sporadic Dobstronomer

Sporadic Dobstronomer

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@Sporadic Dobstronomer

WOW! That is some intricate bit of kit! What size and make of binos are those?

They are Revelation 25x100 (from Telescope House).  Under £200 and not giving pinpoint stars, but a bit of fun!

I bought them while waiting for my Dob to arrive but quickly found it was literally a pain in the neck using them so I made that thing.  The float-glass mirrors I used originally were not good enough so it is only recently that I have had something that works.  The 100x100mm flats are a little undersized but not disastrously so.  That picture was taken on the night of first light.  First light under dark skies is yet to come.

The intention is eventually to fit large Dobsonian-style bearings instead of those wonky screws.  The mirrors do tilt within the box, or I can tilt the whole thing.

And thanks for the compliment!

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Merlin

Merlin

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A problem I have with mounting a laser pen to the mirror-mount is that it doesn't work in cold conditions. I've several pens and all of them have diodes that are sensitive to low temperatures.

A partial solution is to keep the pen warm in a pocket, then, place the pen quickly along the binocular body and fire at the mirror long enough to home in on the target object. Mind you, on frosty evenings, it's only a matter of seconds before the exposed diode wilts.

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Sporadic Dobstronomer

Sporadic Dobstronomer

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A problem I have with mounting a laser pen to the mirror-mount is that it doesn't work in cold conditions...

I too have had that problem.  I have heard that a new kind of laser pointer (with a slightly different wavelength) will be available in several months' time that is not troubled by the cold.

Meanwhile, I am also going to try making a temperature controller to fit on the end of the pointer.  You might find that putting an insulating jacket on yours will slow down the wilting effect (but I have not tried that myself).

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BinocularSky

BinocularSky

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I keep my laser inside the waistband of my trousers.Not only does it stay very warm, but it also discourages others from borrowing it :evil: . If it'll be in my hand for a while, I shove it down the index finger-hole of a fingerless glove (and do that "magic" thing where I point at something then laser it witha blast of green light from my finger :grin: ).

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Merlin

Merlin

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Some observers do, of course, wrap a heating strip round their laser pens, but I prefer to keep things simple and not be dependent on a power supply.

There are/were temperature-tolerant ORION laser pens in the USA, but quite pricey. Are they still available?

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