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Rock Eagle
Trad climber
Central Coast
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Jan 17, 2010 - 11:37am PT
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It is true - Half Dome is visible from the Central Valley on a clear day. I was extremely skeptical when I first read these threads a year ago. So we decided to check it out last March when the visibility was good. Sure enough, the unmistakable image of Half Dome was visible in the distance.
My photo isn't very good, but does show Half Dome.
The coordinates where the photo was taken are N 37° 32.492 W 120° 44.229.
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Peter Haan
Trad climber
San Francisco, CA
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Jan 17, 2010 - 11:49am PT
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Of course agreeing with Clint. I just did the same research the last 30 minutes. Plus I too have seen Yosemite Valley a few times in the last 50 years, from the Central Valley. It is not that unusual; You only need 50-70 mile visibility, which often happens after fall-winter-spring storms. And Half Dome is 8836 ft high, so if you line it up through the mouth of the Valley, you have "Heywhatsthat.com's" visibility claim. Its simple math.
Further, I used the ruler tool and laid out the viewing vector from the spot the photo was taken from (It's actually marked on Google Earth) to the summit of Half Dome and aligning everything, El Cap included, to establish what we view in the photo. The two buildings are also there in the GE viewing.
So no the photo is not a composite but is a fun completely innocent and not-all-that unbelievable 400mm shot, actually.
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Banquo
Trad climber
Morgan Hill, CA
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Jan 17, 2010 - 06:39pm PT
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The gift shop at Mt. Hamilton used to sell prints of photos of Half Dome taken through one of the telescopes.
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neebee
Social climber
calif/texas
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Jan 17, 2010 - 10:13pm PT
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hey there john hansen, and all, say thanks for all this interesting photo stuff, maps and all... and all the links...
thanks again... fun stuff... :)
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Double D
climber
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Jan 17, 2010 - 11:55pm PT
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One of my high school teachers, Phil Arnot, had a picture of HD taken from Mt. Hamilton...near San Jose. It was way cool.
A few years ago on a very clear winter day I took off from SJ on a commercial flight and you could see it clear as day once we circled around and gained a few thousand feet.
Surely that picture will crop up on the internet somewhere.
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ß Î Ø T Ç H
climber
. . . not !
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Jan 18, 2010 - 12:46am PT
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. . Not to weigh down the thread anymore , but look at the edges of the silo or whatever , they look so cut out / ragged compared to the telephone poles in the same area (the wires of the poles don't make sense either) . The photo on my original post is the original size , not an enlargement that would have anomalies or whatever . The camera is obviously of quality too . That's why I think the photo is cooked . Also there is a faint straight line going all the way across the middle of it that seems suspicious .
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Ben Emery
Trad climber
Bay Area
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Jan 18, 2010 - 01:03am PT
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Er, the suspicious faint line I think you're referring to seems to have a slight droop and some possible birds (?) roosting on it at the right; are you sure it's not just an out of focus wire?
The author of the photo (Tony Imoos) has some other good ones of California and Yosemite up on a few photography sites; e.g.: http://www.flickriver.com/photos/trimmoos/popular-interesting/
But maybe I'm just gullible.
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ß Î Ø T Ç H
climber
. . . not !
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Jan 18, 2010 - 01:10am PT
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Again . . the wire is out of focus and the "birds" (more like fleas) are sharply in focus . You can't have the silo that in-focus along with Half Dome etc in the background unless the silo was at least about 10 miles away .
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Ed Hartouni
Trad climber
Livermore, CA
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Jan 18, 2010 - 01:42am PT
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sounds like a job for the SuperTopo mythbusters... except that Rock Eagle already got the photo...
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Clint Cummins
Trad climber
SF Bay area, CA
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Jan 18, 2010 - 03:37am PT
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> look at the edges of the silo or whatever , they look so cut out / ragged compared to the telephone poles in the same area (the wires of the poles don't make sense either) . The photo on my original post is the original size , not an enlargement that would have anomalies or whatever . The camera is obviously of quality too . That's why I think the photo is cooked . Also there is a faint straight line going all the way across the middle of it that seems suspicious .
The cows, trees, grain elevators, roof to right, telephone/power poles, foothill ridges, El Cap, Half Dome, and peaks behind are all in focus.
The grass is the foreground is not. Looks normal to me for a good lens, shot with a small aperture (high F stop).
The telephone/power wires aren't ultra sharp, but that would be asking a lot from a lens at that distance.
Are you saying the grain elevators were pasted in?
They appear in the shots by other people, so they seem to be quite real.
Maybe what several people "feel" is wrong with the photo is that Half Dome looks "too big".
The harvest moon also looks "too big", because it's close to the horizon.
But I and many others believe the moon is real and is not changing size.
Maybe we get fooled by our feelings sometimes.
It may be wiser to be skeptical about your own feelings,
than to suspect others are trying to trick you.
"A wise fox checks his own hole first." :-)
or
"AT A CARDIAC ARREST, THE FIRST PROCEDURE IS TO TAKE YOUR OWN PULSE."
(rule 3. of The House of God)
http://en.wikipedia.org/wiki/The_House_of_God
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monolith
climber
Berkeley, CA
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Jan 18, 2010 - 12:35pm PT
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As Clint mentioned, explanations of the Moon Illusion may apply here.
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John Moosie
climber
Beautiful California
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Jan 18, 2010 - 12:50pm PT
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Dammit Dingus man, now you are making me hungry. hahaha.. Man that looks good.
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ydpl8s
Trad climber
Santa Monica, California
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Jan 18, 2010 - 01:18pm PT
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For those of you who know Colorado....I was on top of La Plata Peak (in the Sawatch)with Craig Koontz when we had just completed the long arduous Ellingwood Ridge at about 2:00 in the afternoon. Craig had hauled a 1,000 mm lens with a doubler on it and a tri-pod up there . He was able to take a picture of Uncompaghre (in the San Juans, which I think is about 90 to 100 miles away as the crow flies, probably double that on the pavement) that filled the viewfinder. The hardest part of taking the picture was waiting to snap the photo between the rising "heat waves" that broke up the picture.
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Ed Hartouni
Trad climber
Livermore, CA
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Jan 18, 2010 - 02:12pm PT
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From Google Earth you can measure Half Dome and find that its face is:
0.53 miles wide
bearing 51º (or lays on the diagonal from the compass points SW to NE)
2000 m altitude at its base
2680 m altitude at its summit
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680 m = 2231 ft = 0.42 miles tall
So roughly 0.5 miles by 0.5 miles.
At 100 miles distance this subtends the angle 0.5/100 = 0.005 radians
An object 1 mile away would subtend the same angle if it were 1 mile * 0.005 radians = .005 miles = 26 feet across.
Camera calculations for digital are confusing because they often quote lens sizes in "35mm equivalent" units... so I'll go with just 35 mm calculations.
For a 1000 mm lens the largest angle subtended by the film would be 35mm/1000mm = 0.035, Half Dome, at 100 miles would take up .005/.035 = 1/7 of the width of the landscape view of such a camera, or 14%
If viewed from the west, however, we have to divide the width of Half Dome by sqrt(2) = 1.414 (multiply by 0.707) and that would reduce the size to something like 10% of the picture width.
You can crop the picture to make the fraction of the frame Half Dome occupies larger... but at lower resolution.
With my FM2N I'd shoot a picture at a high f-stop but with a shutter speed not less than the lens size... my best lens for this would be the 180mm with a 2x teleconverter (TC-200) giving me 360 mm on film. This would make the angular width of the film of 0.10 radians, and half dome occupying 0.0025/0.100 = 2.5% of the film... digitized to 4000 dpi I'd see Half Dome in not more than 100 px wide.
Using the same lens on my digital camera, the equivalent focal length is 540 mm (with the teleconverter) which provides a somewhat larger image of Half Dome... 35mm/540mm = 0.065 radian at .0025/.065 = 3.8%, which gives an image of 163 px wide.
I have a 500 mm reflex lens, but I have found it problematic to shoot at a fixed f = 8, which does not produce images I desire... probably unload that lens and take a deep breath to buy a 400 mm prime telephoto (even used glass is pricey though).
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ydpl8s
Trad climber
Santa Monica, California
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Jan 18, 2010 - 02:49pm PT
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Mr. Hartouni gets an A+ with a smiley face for his answer to the optics "word problem". All of the rest of us that took the test are pissed off cuz he wrecked the curve. :-)
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Ed Hartouni
Trad climber
Livermore, CA
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Jan 18, 2010 - 04:22pm PT
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the Moon's radius is 3474 kilometers, and it's distance from the Earth is 384403, so it subtends an angle of 2*3474/384403 = 0.018 radians 3x Half-Dome's 0.005 radian angle at 100 miles.
This means that you could pick a point to see the moonrise over Half Dome with the moon much larger than Half Dome... it would be killer!
So when might this happen?
The next full moon happens on Saturday 1/30/10, that day the moon rises around 1830, but unfortunately the sun set is at 1715 or so... you'd like to have some sun to illuminate your image.
On Wed 1/27/10 you could have a chance of shooting the moon in Yosemite Valley a la AA, moon rise is 1430 sunset is 1700, the moon's azimuth starts at 53.58º and at sunset is at 78.24º at an altitude of 25.38º sometime between those two times you'd get a great shot... but you would have to travel distance, pick a North-South road...
Your chance after this would be the week before Feb 28 2010...
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Ed Hartouni
Trad climber
Livermore, CA
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Jan 18, 2010 - 05:23pm PT
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The moon has to clear the Sierra crest, so say that's about 2.5 miles high, from 100 miles out that is an altitude angle of 2.5/100 = 0.025 radians = 1.4º
at 50 miles this is 2.8º
so the moon will be visible between 1445 and 1500 on 1/27/10
the maximum "height" of the film is for the 360 mm lens will be 0.1 radians = 5.7º
The moon will be at 6.56º at 1515 which means the shot has a 15 minute window around moon rise. The azimuth of the moon at that point will be 64.41º
According to the chart above, if you set yourself up on G St. in Merced between E Olive Ave and Yosemite Ave, you'd have a shot of the Moon Rise and Half Dome sometime between 1445 and 1515
Slightly better might be Thornton Rd, west of the airport between 140 and W. Dickenson Ferry Rd.
Or on S Gurr Rd (south of W. Dickenson Ferry Rd.)
Be prepared to move North-South, but you don't have a very big window to see Half Dome from this vantage point... maybe someone should be up on Snake Dike waving!
wonder what the weather is going to be like?
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wildone
climber
GHOST TOWN
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Jan 18, 2010 - 06:16pm PT
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Ed, good work-thanks for your time.
Ever check out KEH.com for used high quality glass? Some pro photogs told me about it. I ordered a body and some lenses from them. They know how to assess used glass as they are nikon america's warranty workers.
They are also REALLY good for medium/large format stuff.
http://www.keh.com/
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