Lost Binoculars: Newsletter Challenge (01/29/08)

This one is so simple I wonder why CR4 even dared to put it up.

They can use the magnifying glass and one lens from Alice's glasses to make a rudimentary telescope.

How to build it is all we are left with to speculate or argue about.

I know it sounds easy, but if the lady is having trouble seeing far, that means she is near sighted and that requires concaved lenses to correct. A telescope uses convex lens for an linear type and a concave mirror, flat mirror and one convex lense for a reflecting type. They are still one lense short. I doubt they can convert one of her glass lenses into a mirror.

Also most people have an astingmatism (not sure about the spelling) in which the vertical and horizontal axis's require a different correction factor. This special correction factor would greatly distort the telescopic feature of the scope that is being suggested.

A binocular has two lenses at the eye piece and one in front. about the same as an old telescope or old surveying instruments. all the images are upside down. The binoculars uses 2 sets of prisms to invert the image.

I think Tom has the concave lenses, he was using the pair as an microscope to look for detail.

Binoculars are very handy as a microscope when used from the other end.

Jane (or whoever) only has reading glasses.

Maybe not so easy after all. Normal glasses don't make good telescopes.

Both of them have rare conditions. The combination of 3 lenses (including a concave one) should do the trick.

Maybe Alice should use Tom and her glasses with the magnifying glass held at a distance. The image will be upside down.

Note: I knew a grumpy person that had a concave lens (55 years ago). I never asked him why. Actually never asked him anything. (sort of scared off him, he had one glass eye as well , The glass eye was always looking in my direction )

All the refracting telescopes I have ever seen have only convex lenses!

The telescope Galileo used had a convex objective lens and a concave eyepiece lens. Nearly all (or maybe all) spyglass telescopes use this same optical arrangement, which gives a correct, non-inverted, image without the need for any additional lenses or prisms. [Surely you've seen a kid's spyglass telescope, or have seen a pirate movie where one was used.]

Astronomical telescopes that uses convex lens arrangements for the objective and the eyepiece give an inverted image.

If you've ever pulled apart a magnifying glass, they're often built from two half-convex lenses, with the two flat sides butted together.

That then gives them four lenses to make a true pair of binoculars! (They'll have to cut the map tube in half with their trusty pocketknife)

I think I would feel I'd been lucky if I could build a usable monocular from the available materials, never mind binoculars.

Regarding the two-part magnifying glass: would that be the lightweight moulded plastics types, or a dispersion compensated pair? If the latter, the lenses wouldn't match.

Even if they matched, and Alice's glasses did not provide significant astigmatic correction, Alice wouldn't be able to use the binoculars (the concave lens would merely compensate for her short sight). And if they were just for Tom, they would have great difficulty building a pair of binoculars with usable alignment in the field.

P.S. In "reality", I have strong doubts as to the viability of this solution - Tom is using a magnifying glass to read a map (instead of spectacles?) and Alice is squinting to look into the distance. Are they both completely incompetent, and/or did they both leave their glasses behind, or have we made the wrong diagnosis - and they both suffer from cataracts?

they brought a video camera with optical zoom

The obvious answer has already been given several times, i.e., the convex lens of the magnifier plus the concave lens of Alice's glasses. But, as a birder, I gotta say I wouldn't put all my eggs in that basket (groan). You've have to get it all in a tube, get the lenses on axis and parallel, live with whatever f-stop this thing has, as well as a field of view of ??? And, will the magnification be positive ....or negative?

I think the reason they didn't turn back is that Tom realized Alice was too near-sighted to see the two saber-toothed tigers (hey, it's my park - I can have what I want!) creeping up on them and Alice had the Weatherby slung across her shoulder. So Tom bid adieu and faced his fate.

They didn't have to turn back because as Tom was looking at the map with the magnifying glass, the dumb $**t realized they had gone in a circle.

They moved in circles! I think that this is the answer. Due to the asymmetrical position of the liver in the human body, one step is a little larger that he other one. In places where there is not possible to orientate yourself (desert, forest, sea - if you can walk on the water), one moves in circles. They reached a point where they had a spare pair of binoculars

I once read that this is partly the reason that comets return regularly (I have no idea if this is true or not!!), due to the fact than any straight line you take in space is still in fact part of a circle. The straighter you go, the larger the circle (takes longer for the comet to return!) etc etc etc....

If you wanted to go to the nearest star for example, several course corrections would be needed to "break out of the circle" so to say......(assuming one had the necessary life span and speed for such an endeavour!!)

Perhaps someone with better knowledge can chime in at this point!!!

Because Tom realises that hes found them laying next to his foot?

Because a park ranger pulls up beside them in a jeep and offers to take them back?

Alice remembers she has a telescope in her back pocket?

Because Tom doesn't need glasses and he see's something up ahead?

Dont want to state the blindingly (sorry!) obvious here but....

If he is using a magnifying glass to read the map and she is squinting to see things in the distance why dont they simply swap over what they are doing?!?!?!?!? Then she will be looking at the map and he will be able to see everything in the distance.

They should then be fine - as long as there are landmarks such as shops, cafe's and restaurants on the map!

Women don't read maps. they only ask for directions :^)) But, perhaps that's why you said there needs to be those types of landmarks.

I suspect a "smart" (arse) answer coming as the solution;
e.g. They have sat down on someone else's lost binoculars, or
simply ask their Ranger guide to lend them his binoculars.

However, if this is a "genuine" problem, then Tom will roll up the
map into a tube and use the glass lenses to make a telescope

The lenses held in place by kinks set or slots cut in the tube.

jt.

I used to be an archaeologist; but moved on, when I realised my career
was in ruins.

Such a "smart" answer may be...

"....turn back to get another pair of binoculars."

Because... they are already facing the right way! (back)

jt.

Have a free web page on http://www.mfnb.com

He realized that she had forgotten her glasses, what help will binoculars be?

I guess it depends on your vision but I cant see thru binoc's with glasses on I must take them off.

Well, the real answer is that they can make a monocular with the magnifying glass and the eyeglasses, but the real life answer is that the origninal pair of binoculars are hanging around the blonde's neck...

Conan Doyle would approve of your solution!

Watson: "Holmes, what do you make of this. They will wander in the wilderness until they perish, surely!"

Holmes: "Ah, my dear Watson! As usual, you are reasoning with your heart! They are in no danger, nor will they have to return for extra binoculars. They will continue with their birding expedition to a satisfactory conclusion."

Watson: "But how, Holmes? They require eyeglasses and binoculars which they apparently lack."

Holmes: "Not so. They have all they need. Since you are blessed with excellent eyesight, Watson, you have never tried to look through a pair of binoculars while wearing eye glasses. Most people with poor eyesight will remove their spectacles to use the binoculars. That is evidently what has happened in this case. We have two people, one afflicted with myopia and one afflicted with hyperopia who have removed their eyeglasses in order to use the binoculars. Or perhaps Tom did not even bring his eyeglasses, out of vanity. Without assistance, they are unable to find nearby objects. Tom has finally realized this, and one Alice replaces her glasses, she will be able to retrieve the binoculars!"

Watson: "But, Holmes. How can this be? If Alice is nearsighted, and Tom is farsighted, shouldn't one of them be able to spot the binoculars which are evidently nearby?"

Holmes: "Not necessarily, Watson. Farsighted people cannot see objects clearly which are close. The same often applies to nearsighted people, depending on the severity of their affliction. So, we have two people, with differing vision, who are unable to see objects clearly which are near at hand."

Watson: "Incredible, Holmes! Once you explain it, it seems so absurdly simple!"

Holmes: "Hmph! Just so. Now, we have just enough time for a quick supper at Simpson's and then on to Covent Garden where Irene Adler is performing tonight."

Beautiful, entertaining logic thanks, a sovereign is in the mail. "Hey, BBC 7 bring back the Holmes series. I miss my daily sustenance"

With the map tube, the magnifying glass and the lens of Alices glasses, Tom has enough to make a simple telescope. If he doesn't have a map tube he may have to roll the map around the glass and the lens and make a makeshift tube, which might work better than a map tube anyway. The eye glass lens would serve as an objective lens and the magnifying glass as the eyepiece. Unless he had the means to calculate the distance it may take a few trys to get the correct focal distance. The image would be upside down, but magnified.

Since Alice is squinting (stopping her eye down to a smaller aperture) to see distant objects she is myopic, and will use glasses with negative lenses. Tom has a magnifying glass, which is a positive lens. The map can be rolled up into a tube. These are the necessary components for a Gallilean telescope. They can cement the tube and lenses in place with tree sap. Focusing will be a problem, since Tom who needs a magnifier to read maps is probably hyperopic.

This is going sound simplistic but couldn't Alice compound the far field magnification effects of her glasses using Tom's magnifying glass? I'm sure there is a better way to explain my point in optical terminology but I had to take a stab at it.

They walked to an edge of a cliff. When they looked acrossed, they were even with the tops of several trees, near the tops of the trees, aeries were noted and were within close enough eyesight to clearly see the activity in each aerie. Also, when viewing down the face of the cliff....guess what? More aeries were discovered and well within eyesight. No binoculars were needed!

take magnifying glass and glasses holding them in line to produce a telescope

Tom aims his magnifying glass at a clump of dried hay causing a fire (small and contained one mind you), and then hides. Because it is a national forest there will be steady and intense satellite surveillance. When the smoke is spotted, crews are dispatched to the origin of the smoke where Alice uses her womanly charms to both borrow a pair of binoculars, and be forgiven for starting a fire in a national park.

Sounds easier for Tom than dragging a half-blind Alice around the wilderness after he dismantles her glasses, and wastes hours trying to focus 3 lenses without mechanical precision.

I would think with two concave lenses and a magnifying glass they could roll the lenses into the map adjusting the lens spacing for focus, assuming alice is squinting because of her eyesight. maybe she is squinting because its nearly sunset, the sun is in her eyes and they don't need to go back and get binoculars, they need to go back because its getting dark. After all they were hiking for many hours.

Because he just saw them around his neck, what an Idiot....

Now they don't have to go back,

I hate when that happens.

Would that be Alice of "Alice through the looking glass"?

Forget all of the claptrap about building telescopes out of reading glasses. All they would need to do is put a pinhole in their map and look through this. Pinhole lenses have been around since the first daguerreotype and probably earlier. There are tricks to making this work better. One is to use foil (luckily Alice's New Year's Resolution to quit smoking was a total failure). The foil allows for a smaller, rounder hole and a darker surrounding area. Also, excluding stray light helps the eye deal only with "image" light, giving better contrast.

Try this: on a sunny day, find a sign that is just too distant to read. Then stretch a piece of aluminum foil over the end of a half length toilet paper inner roll and look again. I'll bet you can read it now. Good clean fun to amaze friends and gain "cool" points with kids.

A refinement on this are pinhole "glasses" that provide a series of pinholes in solid plastic lenses, available from any health food shop in Australia. Cheap as chips and, daw shucks, I have given my last pair away to an amazed short sighted person, time to GoogleShop for some more.

Yes, a sunny day. Very sunny

This can help by reducing glare if the day is very bright. If your eyes are not perfect (you have astigmatism, or are short-sighted or extreme long-sighted), it can also provide a significant improvement in the quality of focus. Finally, it can provide a very small measure of enlargement if (and only if) you are long-sighted. But act as a telescope - not so far as I can tell - neither experimentally nor by ray tracing.

Given one is looking for landmarks, and one is studying a map, should it be considered that they are lost? If after 2 hours Tom is still the magnifying-glass-map-reader, and Alice is the squinting-landmark-spotter, then they have not selected tasks appropriate to their capabilities (see #14).

Let's assume they are lost. Returning for another pair of binoculars is not necessary because it is not possible. If they could return, then they are not lost. Who bothers with maps these days? What happended to their GPS? They are only a couple hundred bucks.

Tom chokes on issuing the sarcastic comment because he realises that they are lost, without GPS and that is not funny. But he still thinks of the irony. Hey, he's an optimist. Yep, they are lost. No GPS. Thinning the herd. Hope they don't have kids.

Alice is far-sighted, Tom is near-sighted. If Alice uses the magnifying glass she will be able to focus at a much greater distance - her vision and the magnifying creates a telescope.

Don

He simply pulls out his sony camcorder with 990 zoom and films the little guys. or uses a water bottle for the other covex lens if Alice has no glasses. or finds a pop bottle some inconsiderate left behind. if they are lost just get some water in a glass and drop (gently) a needle on the H20 for a handy compass (Yes it will float or at least not sink) due to surface tension. remember to adjust for true north.

Bill Cz

Since Alice has to squint to see landmarks, she is evidently near-sighted, and her glasses are concave (negative focal length). Tom's magnifying glass is convex (positive focal length), and the glasses and magnifying glass together will form a telescope.

What are 2 optical disabled moles doing in the wild?

I think Jane would have been much more for the eye,

And I think a normal sighted Jim would realize "who needs a map and a binoculars to study birds and bees anyway?"

The administrators should get lessons in choosing the right team for the job.

Fancy going walking without a compass, surely "walking gear" refers to such items as Map, compass, GPS, ALL the correct survival gear to under take there expedition, Obviously they did not carry out a risk assessment before leaving.

Although in densly forrested areas the GPS would probably be of no use.

I would never take a pair of binoculars to see landmarks while map reading, Would suggest the guy goes to the opticians if he ever gets out of there alive!

As someone has said roll the map up and tape the lenses to each end, then look for the exit sign, then go home

I don't think the question exactly says that they're lost. They may just want the binoculars for observing the Eagles. Perhaps a naive Eagle has landed in front of them, so they are close enough.

I believe that Tom simply noticed the moss growing on a tree trunk, remembered the reason for that, (lack of sunlight) and from that, he knew one sure direction, north! From that information, they can use the map to get out of the forest, before nightfall.

Never mind the binoculars. They aren't necessary at this stage in their adventure.

Just a thought

So, the answer is that after Alice/John had her sex change operation, Tom simply swiped the surgeon's car, drove back to town and bought a decent monoscope (which is what you really want for birding anyway).

ROFL ! This has got to be one of the funniest mix-ups ever.

Who the heck is John in the answer?

See Alice John

What does a Welsh bald eagle look like?

The answer given to this question is unlikely to work. The magnification of Gallilean telescope depends on the ratio of the focal lengths of the two lenses, namely (focal length of the convex lens)/(-focal length of the concave lens). A weak magnifying glass would have a focal length of about 5 inches, and stronger lenses would be shorter. A strong eyeglass lens for correcting farsightedness would have a focal length of -10 inches, and weaker ones would be longer. Thus the best case of a weak magnifying glass and a strong eyeglass lens would be hard pressed to have any magnifying ability at all.

Don Shepherd

Alice John (born 1881) would be short-sighted - not long as implied in your posting. She actually suffers from a combination of strong myopia and presbyopia, and is still wearing her walking glasses, which is one reason she is squinting*. Strong myopia is defined as more than 6 dioptres, or about 6-inches focal length. Fortunately, Tom May still has a penknife with a screwdriver that can loosen the lenses from Alice's glasses, so he can combine lenses from two pairs (needed because of her extreme presbyopia) to provide a lens with a virtual focus of 1.5". In addition, he is able to unscrew the frame of the magnifying glass to extract one of the lenses, to give a real focal length of 12". That seems to be a satisfactory x8 magnification when used in "standard" Galilean mode.

*The other is her cataracts.

No, I got it! Is it too late to enter? Darn!

Here's the way it plays out. Every year, John dresses up as Alice and goes out with Tom to this spot. Every year, "Alice" pretends to have forgotten the binoculars, and Tom begins to berate her. Then "Alice" sheds her disguise to reveal Forest Ranger John who tells Tom he's under arrest for violating the Endangered Species Act. Then John handcuffs Tom to a tree and says "I just can't quit you."

This is the plotbook for the pilot show of "Brokeback Aerie".

OMG ROFL!!!!!

wow ... got funnier as i read more.

Who the He_ _ is John? Where did he come from?

...and what is Tom doing with a lens from his glasses?

Tom and Alice realize they are deep in the forest with no one around and decide to get naked. They end up pleasuring each other for hours.....

Meanwhile a forest ranger found the binoculars and ..........

That is...until she finds out about John.

Are we still waiting on the "true" answer, or did I miss it?