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Reilly
Mountain climber
The Other Monrovia- CA
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Dec 28, 2012 - 07:43pm PT
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Isn't 1/125th a little slow for a 500 without VR? I suppose with the
mirror up on a good tripod it will do? How fast does the moon move?
I know you mentioned it before but I guess 1/125 is fast enough for that?
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Ed Hartouni
Trad climber
Livermore, CA
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Dec 29, 2012 - 04:00pm PT
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ok, got a chance to reduce my data...
the first hint of the Moon was at 16:48
here rising over the Sierra crest
This was a bit later than I had expected in my calculations, but points out a problem with this shoot, I didn't setup good landmarks for determining azimuth or altitude... owing to the fact that I had gone with the expectation of seeing Half Dome which would have been the landmark.
In the future I'll have to make sure to have secondary "targets" to establish the directions from my station.
The data from the images with the moon are seen in this plot of apparent altitude versus azimuth:
which shows the expected trajectory as the red dashed line. This is consistent with a 0.29º shift in azimuth which is very possible since I established the azimuth off of the pine tree in the image above... about 3/4 miles away.
Another task for this shoot was to establish probable exposures. The image above was shot at f8, 1/125s and ISO 100, and was very dark (the image is corrected in Photoshop with Brightness=2.94 to make it equivalent to f4) . I could have shot at f4, two stops down. The bright Moon overhead is usually shot at f11. You expect that the light going through the atmosphere is attenuated more at the horizon since the length through the atmosphere is longer than when the Moon is at its zenith (over head). I averaged the brightness of the pixels on the moon images as a function of apparent altitude and was surprised to see this:
the red dots are the data, the 6 "low" points are taken with f8 (the lowest) f5.6 (the two intermediate) the rest at f4... a rough correction shows that the Moon gets brighter as it ascends, but that there is a point below which it doesn't change. The solid line is what you'd expect if the attenuation was due to the light's travel length in the atmosphere.
Thinking about this it is possible to contrive an explanation which has all of the light of a particular wavelength extinguished, while light of other wavelengths is passed, which could be due to aerosol size, for instance, so it is not unreasonable. Once the path length gets short enough, the light starts to get through and the overall brightness of the Moon increases.
The speed of the Moon here is 0.0037º/s, and for this camera with this lens that translates into a 2.1 pixel/s motion. Blur due to the Moon's transit will not be a factor at 1/125 s exposure times, basically 0.02 px... The distortions of the image are due to the convection changing the index of refraction along the light path.
The whole scene would have been nice in this image:
with Half Dome down and to the left of the Moon... but for the clouds...
The darkness of the foothills is due to low cloud cover all the way out to the coast... the hope would have been for clear skies and an alpinglow cast on the Sierra, and Half Dome.
The reason for all the calculations is that the shot doesn't last that long, so everything has to be setup for the shot ahead of time... and basically happening automatically during the time. Here is what the different lens Fields-of-View look like:
where the bright purple line is the presumed azimuth of Half Dome. Had the conditions been excellent I might have attempted the shot with my 500mm reflex and the x2 teleconverter, so 1000mm effective, but at f16 fixed I'd have had to decrease my exposure times to 1/8 s, the Moon would be traveling across the scene at 12 px/s, which would have lead to a 1.5 pixel blur, probably not horrible given the very soft focus of that lens combination.
With these calculations I would have gotten the shot having lined up on Half Dome. That's good to know, I would probably not have gotten a good exposure, but I'll work on setting up automatic bracketing in the camera.
I'd love to get that shot though... for me February will be the next possible time... maybe Banquo will have something for us in late January!
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Ed Hartouni
Trad climber
Livermore, CA
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Feb 18, 2013 - 12:18am PT
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it's that time again, and weather will be a consideration...
there are three days:
Fri 2/22, moon rise: 15:13, azimuth 71.15º
Sat 2/23, moon rise: 16:21, azimuth 75.55º
Sun 2/24, moon rise: 17:21, azimuth 80.77º
sunset is around 17:45
The weather forecast is for cloudy on Fri and Sat, and clear on Sun, then it get's cloudy again, so there is a small window which is a moving target...
On Sunday, the closest location in the Half Dome view space is on Montpellier Rd., 0.2 miles south of the intersection with Hall Rd. looks like open fields to the east in Google Earth.
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Ed Hartouni
Trad climber
Livermore, CA
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Feb 23, 2013 - 12:09pm PT
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ok, missed yesterday... couldn't work it into the schedule....
four potential sites for today, listed in order of distance:
site 1: on East Ave., 0.95 miles east of Santa Fe Ave
site 2: on Santa Fe Ave, 0.28 miles southeast of the intersection with East Ave.
site 3: on N. Vincent Rd., 0.48 miles south of East Ave.
site 4: on S. Story Rd, 0.69 miles south of East Ave.
main criteria will be visual sighting of Half Dome... hopefully it will be breezy enough to blow the haze away...
These are on the azimuthal bearing of the moon rise, the moon will be slightly south of Half Dome when it appears over the Sierra crest at roughly 16:15
I'll bring a lot of cameras and get other "opportunity shots" if the blossom is in
I plan on being on site an hour before the moon rise... but I don't know which of these 4 places I'll be...
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climbski2
Mountain climber
Anchorage AK, Reno NV
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Feb 23, 2013 - 12:17pm PT
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The intersection of astronomy and surveying is making for a compelling photographic discipline! Hopefuly the meteorology will cooperate. Good luck!
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Reilly
Mountain climber
The Other Monrovia- CA
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Feb 23, 2013 - 12:38pm PT
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Too bad you don't have the new Nikon 800mm- it would be perfect! ;-)
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Banquo
climber
Amerricka
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Feb 23, 2013 - 02:23pm PT
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Good luck. I'll be in SF having dinner with my kid.
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Ed Hartouni
Trad climber
Livermore, CA
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Feb 24, 2013 - 12:36am PT
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not a good day...
shot with the FujiFilm S5Pro
180 mm Nikon lens
2x Nikon teleconverter
f8 1/125s exposure at ISO 100
...clouds over the Sierra, none of the potential sites worked out with a view either... perhaps I'll try again tomorrow if the weather is better.
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john hansen
climber
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Topic Author's Reply - Feb 24, 2013 - 12:42am PT
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Hey Ed, thanks for trying,, the quest continue's.
Looking forward to when you get it.
The valley air looks pretty clear, and the Moon looks great,, you can see the clouds over the coast range and the mountains accross the vally, nice photo. someday soon, perhaps tomorrow.
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Mike Bolte
Trad climber
Planet Earth
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Feb 24, 2013 - 01:06am PT
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Ed - this is a lot of fun to follow your thinking and efforts!
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mouse from merced
Trad climber
The finger of fate, my friends, is fickle.
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Feb 24, 2013 - 11:16am PT
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It certainly is, Ollie!
I keep looking for some signs like the wind last night, and the chill as a result, hoping for clarity. This a.m. the mountains just seemed so far away compared to other days. It's really clear, but the distance seems rather MORE distant than close, in comparison with other clear mornings...
What's up with that, Newton (rhetorical) ?
This morning.
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Ed Hartouni
Trad climber
Livermore, CA
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Feb 24, 2013 - 11:36am PT
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I'll start differently today... on the west side of the Central Valley southeast of Grayson (on Elm Ave near Loquat Ave) and move along the moon-rise-over-half-dome bearing of 80.77º with the intention of spotting Half Dome first...
8 potential sites are identified on the basis of the Google Earth (GE) indicator of possible locations with a view (e.g. no groves or buildings)... the altitude of the Sierra Crest is about 1º (0.0175 radians) which means that a 20' tall tree obscures the view if you're closer than 1146' (0.21 miles)...
This is more of a problem farther away from Half Dome than closer... but it provides a bigger range of possibilities of views.
another improvement for today: I finally looked up the magnetic declination in the area, -13.72º (magnetic north is east of true, e.g. GE, north) which means I can use my compass to get an idea of just where I'm looking rather than trying to do that off of sight cues, I don't know the Sierra Crest that well (yet) and even if I did, the cloud cover obscures many of the important points.
the farthest east potential view point is on Montpellier Rd south of Hickman (just south of the intersection of Hall Rd.)
as far as why it looks so far and seems to be clear?
don't know exactly but we perceive distance by a number of cues, one of which is the "atmosphere" which attenuates light as a function of the distance it travels... the ground fog this morning gives you 100% humidity near the ground, so the base of the mountains might look far, but the tops of the mountains don't travel through as much atmosphere, the humidity might be half or less... so the tops look close... your brain puts that all together and the result is a rhetorical question...
the humidity today isn't going to be very low, 54% around the time of sunset, and 18% cloud cover... so I'm not hoping for too much...
for photography you want to have clouds, but in the right place... given the constraints of this shoot, it's a timing issue... and so far the timing hasn't happened...
...but it's still fun.
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Srbphoto
climber
Kennewick wa
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Feb 24, 2013 - 03:35pm PT
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Am I the only one who doesn't understand half of what Ed writes? :)
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Ed Hartouni
Trad climber
Livermore, CA
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Feb 25, 2013 - 03:38am PT
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well, close, and artistic, but not quite a success…
The schedule for today:
Sunday
2/24/13
-2.38 78.87 17:00
0.00 80.77 17:13 moon rise
0.43 81.11 17:15
1.00 81.56 17:18 moon at Sierra Crest
3.26 83.34 17:30
6.11 85.56 17:45 sunset
80.77º true
67.05º magnetic
after a morning gym sesh with Dr. Sharpe I launched from home with a thorough plan, 8 possible view points. The drive over and back from Sunnyvale was revealing high clouds, lots of moisture, and still winds aloft which seemed considerable.
I was on the road by 1:10pm and after a fuel up the first real indication of conditions was summiting Altamont Pass on I-580, and I saw the snow clad Sierra. That was a relief since actually seeing it gave me a chance.
Starting this quest from East to West the first stop was near Westley. But I blew the approach by not having my instructions and ended up way South. Still, I had plenty of time, I arrived at "Site 8" at 3:06pm, which was supposed to be 0.1 mile SE on Elm Ave from Loquat Ave… 37.52988ºN, 121.12800ºW which was about 123' short of my intended line… not bad.
Sighting Half Dome was the main task, and though it was hazy, and this location was 88.71 miles from the summit, I still was able to locate it and get two images, one with the 180mm x2 and one with the 500mm x2:
Half Dome is just up an left of the tower at image center.
It is HUGE compared to the background… didn't expect that, at least with a 1500mm lens (equivalent on the DX format sensor).
The next stop "Site 7" was on Vivian Ave 0.73 miles south of W. Keyes Rd. at 3:34pm, my location was 37.54195ºN, 121.04860ºW, which was 390' north of where I intended… once again, Half Dome was located and shot:
look just above the "barn" slight left of center in the image…
here with the longer lens. This site was 84.32 miles away.
Site 6 was at 37.54760ºN, 120.99370ºW, 385' south of the line, the view was obstructed by hedges on the road and at the other side of that particular lot of land. When I look at Google Earth (GE) again I can see the hedges, the shadow angle didn't reveal their height.
I missed Site 5, didn't write the distance down, Site 4 view was obstructed by trees, as was Site 3. These trees were distant on the GE look, but the tree height was sufficient to block the Sierra crest view. I hit the Site 3 location at 37.56570ºN, -120.87272ºW just 27 feet East of intended. My anxiety was rising, however, since I hadn't spotted Half Dome since Site 7, there was little more than an hour to Moon Rise and the thought of going all the way back to Site 8, the best view of the two seemed a bit improbable.
I landed at Site 2 at 4:15pm and found it to be a terrific site, though I was having trouble spotting Half Dome. With time running short a quick hope over to Site 1 revealed it to be obstructed by a hill and trees, so quickly back to Site 2 at 4:26pm, 37.58155ºN, 120.75567ºW, 212 feet South of the intended position.
With the view, and the low light, I didn't see Half Dome. I should have looked at the set of images that I had taken, but decided, instead on going with a slightly wider angular field of view afforded by the 180mm x2 combination 3.66º and hope to find Half Dome in the image.
This was the scene:
and you'll notice right away that Half Dome isn't there, it's off frame to the left. This should have been a disaster, but it wasn't, somehow I messed up my calculation of the azimuth of the Moon Rise, or the bearing from the view point.
My times where correct, however, though in disagreement with Debbie's Garmin GPS Celestial page information. Of course this caused a lot of angst (GPS calculated 3 minutes earlier). I expected the Moon to be at the Sierra Crest around 5:18pm.
Having setup, I started the exposure timer at 5:05pm. This was set to "click" every 7 seconds. I had the camera in "mirror up" mode, so the first "click" brought the mirror up, the "click" after that exposed an image. I also had the camera "auto bracket" the exposure +/- 0.7 stops. In this mode the timer "clicked" the mirror up, then "clicked" an exposure with my settings, then clicked the mirror up, exposed with +0.7 stops then clicked the mirror up, and exposed with -0.7 stops. So every 6x7=42 seconds the process repeated itself.
I had the iPod tunes running and the binoculars out trying to chill. The haze was a bother, but the state of the atmosphere east of the Sierra crest was an unknown. The Moon will arrive like the Cheshire Cat's smile, slowly emerging from the mirk, it's not obvious at first, but then it is there:
By my calculation, this should have been off the image to the left…
two minutes later:
I dropped out the x2 Teleconverter and got a wider view:
if you're good you can pick out the top of Half Dome just above the foreground ridge in the bottom left of the image… I'll ID the peaks over the next week, too tired to do it now.
final view through the haze…
My calculations were off, I'll ponder that too... and the images need a bit more work, this is a quick pass through
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The Lisa
Trad climber
Da Bronx, NY
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Feb 25, 2013 - 09:33am PT
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Ed, this sleuthing work is fascinating. Sounds like you had a very productive day yesterday.
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Ed Hartouni
Trad climber
Livermore, CA
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Feb 27, 2013 - 03:23am PT
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the crest...
now I'll be able to check the Moon position as a function of time with azimuth and altitude information... but not tonight.
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john hansen
climber
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Topic Author's Reply - Feb 27, 2013 - 05:44am PT
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That is pretty impresive Ed.
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Roxy
Trad climber
CA Central Coast
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Feb 27, 2013 - 09:34am PT
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Ed your efforts to get the shot are awesome.
thank you for sharing the journey.
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mouse from merced
Trad climber
The finger of fate, my friends, is fickle.
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Feb 27, 2013 - 10:47am PT
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In your light we see light. Psalm 36: 9.
I must thank you, Eddly, for the explanation^^^. Lucid. Didactic, even! do you tap dance, too? :)
Oh, beauteous photos, too. Man-Oh-Man!
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