Here's a puzzle for you...

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Vorpal
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Re: Here's a puzzle for you...

Postby Vorpal » 28 Jun 2015, 9:17pm

Manc33 wrote:My only problem with it is whether the Concorde has curved windows or not, only the manufacturer could or would know that (unless someone put a small metal ruler up against the glass to check) but it only needs to be ever so slightly curved for something ten miles away to be affected.

You can go look at one at Duxford.
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TonyR
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Re: Here's a puzzle for you...

Postby TonyR » 28 Jun 2015, 9:59pm

Manc33 wrote:What plane are you getting on that goes to 60,000 feet?

The limit of commercial airplanes is about 45,000 feet.


Concorde was 60,000ft

Something straight that is ten miles away being viewed through curved glass will be more curved than something that is straight that is a few hundred feet away. Bending physics and optics isn't required, just a difference in distance - a big difference - 10 miles (the horizon) is 528 times the distance of 100 feet.


You clearly have no understanding of basic optics. Would you care to tell us which optical distortions are creating this effect you are claiming for a constant thickness piece of glass with a slight curvature on it?

But lets just assume you were correct. How do you explain the horizon not being curved when it is 200 miles away from a plane at 30,000 ft but curved when viewed through the same window at 60,000ft when the horizon is 300 miles away?

Then there's the fact that any photo taken on a plane is with a camera with its own lens, whatever effect that might have on things


But I saw it with my own eyes, not a camera so explain that away.

What is there to not believe about curved glass having this effect given the massive differences in the distance?


Everything!


My only problem with it is whether the Concorde has curved windows or not, only the manufacturer could or would know that (unless someone put a small metal ruler up against the glass to check) but it only needs to be ever so slightly curved for something ten miles away to be affected.


Only in your version of physics and optics, not in the generally accepted version.

jochta
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Re: Here's a puzzle for you...

Postby jochta » 29 Jun 2015, 12:11pm

TonyR wrote:But I saw it with my own eyes, not a camera so explain that away.


Your eye has got a curved lens in it obvs.

Manc33
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Re: Here's a puzzle for you...

Postby Manc33 » 29 Jun 2015, 3:27pm

Tony you said "the next time" and were referring to Concorde. There can't be a next time if it was retired in November 2003.

Which optical distortions?

The optics aren't distorted, the glass is.
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TonyR
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Re: Here's a puzzle for you...

Postby TonyR » 29 Jun 2015, 5:42pm

Manc33 wrote:Tony you said "the next time" and were referring to Concorde. There can't be a next time if it was retired in November 2003.


Yes, and if there was I really would open the window at 60,000 ft to look out.

Which optical distortions?

The optics aren't distorted, the glass is.


Take your pick. You can choose from on-axis distortions, off-axis distortions or geometric distortions.

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gaz
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Re: Here's a puzzle for you...

Postby gaz » 30 Jun 2015, 9:04pm

There's a leap second tonight, don't forget to change your clocks :wink: .
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Manc33
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Re: Here's a puzzle for you...

Postby Manc33 » 1 Jul 2015, 1:54am

gaz wrote:There's a leap second tonight, don't forget to change your clocks :wink: .


I enjoyed every millisecond of it. :P

Here's one and it is a real one, I would love it if an astronomer/photographer/scientist could answer it...

I looked at the moon tonight through a pair of £15 binoculars and I could focus perfectly on the moon. I could see those lines on the moon that come out from a crater, which I would say is quite fine detail. I didn't need a tripod. The focal point wasn't at the end of the focal range, but more like around the middle of its range. If the moon is 238,855 miles away, how is it that I can focus on it from that distance, with cheap handheld binoculars?

Why are there binoculars that cost thousands of pounds, if £15 ones can focus on something that far away?
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661-Pete
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Re: Here's a puzzle for you...

Postby 661-Pete » 1 Jul 2015, 8:56am

You don't need particularly powerful binoculars to see plenty of detail on the moon (the best times of the month to look are when the moon is at one of its quarters and there is plenty of cross-light). Galileo was able to make out quite a lot of the moon's surface and his telescope was considerably inferior in performance to even the cheapest modern binoculars.

If you want to study deep sky, pick out Jupiter's moons, or split easy binary stars like Albireo, you'd need something a bit more upmarket. I use a reasonably good pair of 10x50's - that's about the highest power suitable for the typical user. Anything bigger, you'd probably need a tripod unless you've got exceptionally steady hands.

What you can see also depends on your eyesight. Some people can see far more than others, through the same binoculars. One memorable night, when I and several other amateur astros were congregated in Patrick Moore's back garden, as it happens - while we were waiting our turn at the telescope, I amused myself by trying to pick out the spiral galaxy M33 (the Triangulum galaxy) with my bins - then I invited the others to have a go. I, and some of the others, could see it. Others could not. That's pretty close to the limit for binocular observation and needs really dark skies. If you're willing to have a go (in the Autumn) I can give you directions...

If you normally wear glasses, particularly those with astigmatic correction (as I do), keep them on and choose a pair of bins with large eye relief. Often they will have rubber cups around the eyepieces which you can fold back.

But certainly, the £1000-plus binoculars are strictly for the 'professional' amateurs like comet-hunters. That hobby needs serious dedication!
Pete

Et qui rit des curés d'Oc?/De Meuse raines, houp! de cloques./De quelles loques ce turque coin./Et ne d'anes ni rennes,/Ecuries des curés d'Oc. - Louis d'Antin

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661-Pete
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Re: Here's a puzzle for you...

Postby 661-Pete » 1 Jul 2015, 9:04am

Manc33 wrote:The focal point wasn't at the end of the focal range, but more like around the middle of its range.
That would be because many binoculars are designed to focus 'beyond infinity', this is helpful to users with severe myopia (shortsightedness) who prefer to observe without their glasses or contacts.
Pete

Et qui rit des curés d'Oc?/De Meuse raines, houp! de cloques./De quelles loques ce turque coin./Et ne d'anes ni rennes,/Ecuries des curés d'Oc. - Louis d'Antin

TonyR
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Re: Here's a puzzle for you...

Postby TonyR » 1 Jul 2015, 10:04am

Manc33 wrote:
gaz wrote:There's a leap second tonight, don't forget to change your clocks :wink: .


I enjoyed every millisecond of it. :P


Surely not celebrating the heliocentric spherical earth hegemony :shock:

Here's one and it is a real one, I would love it if an astronomer/photographer/scientist could answer it...

I looked at the moon tonight through a pair of £15 binoculars and I could focus perfectly on the moon. I could see those lines on the moon that come out from a crater, which I would say is quite fine detail. I didn't need a tripod. The focal point wasn't at the end of the focal range, but more like around the middle of its range. If the moon is 238,855 miles away, how is it that I can focus on it from that distance, with cheap handheld binoculars?

Why are there binoculars that cost thousands of pounds, if £15 ones can focus on something that far away?


What you should really be concerned about is why when you look through them one way the moon is so close but if you look through the other end it's so far away. If you are looking through binoculars one way and a friend is looking through the other way at the same time how can it be in two places at once? :roll:

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Re: Here's a puzzle for you...

Postby Manc33 » 1 Jul 2015, 1:31pm

I just find it amazing that it can be focused on in that way considering it is a quarter of a million miles away.

You'd think it would need micro adjustments to focus on it. For this reason I can't comprehend how it can possibly be that far away. The binoculars are just made for amateur bird watching or whatever.

Its not the focusing to infinity part itself I have any problem with, but its the fact that it doesn't need a micro adjustment and you can - with quite a big turn of the focus wheel - bring it in and out of focus. :shock:

Take the circumference of the Earth at the equator and multiply that by ten times and that's where they tell us the moon is. I am sure there's an explanation, not necessarily an answer, but an "explanation". :wink:
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Re: Here's a puzzle for you...

Postby Vorpal » 1 Jul 2015, 1:34pm

Clearly, it's because the earth is flat and the moon is a lamp in the ceiling.
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TonyR
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Re: Here's a puzzle for you...

Postby TonyR » 1 Jul 2015, 1:51pm

Manc33 wrote:I just find it amazing that it can be focused on in that way considering it is a quarter of a million miles away.

You'd think it would need micro adjustments to focus on it. For this reason I can't comprehend how it can possibly be that far away. The binoculars are just made for amateur bird watching or whatever.

Its not the focusing to infinity part itself I have any problem with, but its the fact that it doesn't need a micro adjustment and you can - with quite a big turn of the focus wheel - bring it in and out of focus. :shock:

Take the circumference of the Earth at the equator and multiply that by ten times and that's where they tell us the moon is. I am sure there's an explanation, not necessarily an answer, but an "explanation". :wink:


You need to look up "depth of focus". Basically anything beyond a hundred metres to infinity and beyond is in focus at the same time as far as the binocular optics are concerned

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Re: Here's a puzzle for you...

Postby Manc33 » 1 Jul 2015, 2:08pm

Yeah it is I remember it on camera lenses years ago as a kid, my bad. :oops:
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Mick F
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Re: Here's a puzzle for you...

Postby Mick F » 1 Jul 2015, 2:11pm

Not ours.
Ours need focusing up to a mile or thereabouts.
Ours are small 10x25 Bushmasters.

I suppose the focusing thing is dependent on the magnification. Bigger magnification means the need to focus further out.
Mick F. Cornwall