Half Dome picture from some where around Turlock

Search
Go

Discussion Topic

Return to Forum List
Post a Reply
Messages 141 - 160 of total 178 in this topic << First  |  < Previous  |  Show All  |  Next >  |  Last >>
mouse from merced

Trad climber
The finger of fate, my friends, is fickle.
Dec 28, 2012 - 09:38am PT
"Hey, way out there," Patrick! (the best I could do for a view of what you wished to see)

Search "Mount Diablo Vistas" on "Google" "OK"?

"Mouse"
I posted the copied link, but it's failing.
mouse from merced

Trad climber
The finger of fate, my friends, is fickle.
Dec 28, 2012 - 11:11am PT
Credit: mouse from merced
This morning, just After Seven, from Mouse's.

No wind last night, freezing at rooftop level.
8:00 a.m., ice water on the next-door roof.  Don't need a weather repo...
8:00 a.m., ice water on the next-door roof. Don't need a weather report at my place. Just look out the window.
Credit: mouse from merced

That moonrise was real nicely-edited and the music's mellow, Ed. Good on you.
Banquo

climber
Amerricka
Dec 28, 2012 - 01:03pm PT
I went to take a look but from a different spot than Ed. I opted for a shorter drive from my house. This was taken from the I5 overpass at Taglio Road near Gustine.

Based on the Naval Observatory http://aa.usno.navy.mil/data/docs/AltAz.php the predicted Gustine moon position was:

PST ------ Alt(deg) - bearing(deg)
16:46 ----- 0.5 ------ 64.9
16:47 ----- 0.7 ------ 65.1
16:48 ----- 0.8 ------ 65.2
16:49 ----- 1.0 ------ 65.3
16:50 ----- 1.1 ------ 65.5

From my location Half Dome should have been in a bearing of 66.3 degrees and 92.5 miles away. I've sketched in Half Dome roughly the correct size but I simply guessed how high to place it in the image. The clock in my camera was about 12 seconds slow if you check the EXIF data.

Credit: Banquo

Moonrise over Half Dome
Moonrise over Half Dome
Credit: Banquo
Dingus Milktoast

Gym climber
And every fool knows, a dog needs a home, and...
Dec 28, 2012 - 01:27pm PT
From my personal experience its the snowy backdrop of the high Sierra behind, which renders Half Dome visible. Given the sun will have set and the moon is rising behind half dome, doesn't this lighting play against the goal?

You need a really big flash!

DMT
Banquo

climber
Amerricka
Dec 28, 2012 - 01:58pm PT
DMT -

Yeah, moon photography is a problem. The moon is in full sunlight and should be exposed accordingly. Dusk is getting pretty dark for the terrestrial part of the image. Summer would be good since the sun sets much later but the visibility is never good then.

The next full moon is on Jan 27 but it doesn't rise until 6:30 pm when it will be too dark to see half dome.

On January 24 the moon will be 95% and rises at 3:30. This might be good enough if it is clear.

Dan
Ed Hartouni

Trad climber
Livermore, CA
Dec 28, 2012 - 02:01pm PT
the trick will be to get the Moon rise with sun still on Half Dome
and with a very long lens... which stresses the accuracy of the calculation of the trajectory of the Moon as seen from some location in the central valley...

I'd hope to get 360mm or 500mm lens on the scene, perhaps even 1000mm if the light is excellent...

the angular field-of-view at 1000mm is about 1.4 on my sensor, the Moon is 0.5 so it takes up a very large area, but it's also moving fast, requiring a quick exposure time... the aperture can be set larger than the typical full Moon setting of f11 at 1/125 s because the atmospheric attenuation is large viewing it on the horizon... looks like f4 at 1/125 s was fine for my last effort... 3 stops down (1/8 th the light) but that doesn't give much room for the exposure unless the lens is very fast (my 500 mm reflex is f8, with a x2 teleconverter this goes to f11)... if the scene is too light, the Moon-sky contrast is not so great and the effect is diminished...


anyway... it's a fun project...
Banquo

climber
Amerricka
Dec 28, 2012 - 05:54pm PT
Ed-

If Jan. 24 is a clear day it should work.

Good, long focal length lenses are terrifically expensive. I see some nice ones in the 10 k$ range but I won't be buying one. I have a super cheap 500mm reflex lens but it is hard to get good photos with. My aging eyes have trouble with the manual focus and like all reflex lenses the contrast is poor. If one had a big mega pixel camera and a good lens in the 200mm range, a cropped image might do.

I did learn a few things yesterday that will be helpful if I try again. The position predicted by the Naval Observatory seems to match the photo I got. It seems like they must account for atmospheric effects. I would try to get an image when they predict the moon is about 0.7 degrees elevation. I think it would look best with the moon a bit left of HD so I should have been a bit farther south than I was.

My next target is about 3:27 pm on January 24. The moon will be on a bearing of 64.5 degrees. I think a position along a bearing of 65 degrees from HD would be just about right. By I5 where Butts Road crosses the California Aqueduct would work and There is some elevation there to look over the orchards. Also Lincoln Blvd about 0.5 mile south of 140 if there is a clear view from there.
Ed Hartouni

Trad climber
Livermore, CA
Dec 28, 2012 - 06:25pm PT
right now my climbing schedule will have me in Cody WY on the 24th... so I'll miss that one... try for Feb.

I suspect that the differences between the "apparent" altitude and the "actual" would be more to do with timing than with position as the corrections are pretty small...

most of the lenses I've bought are used, that brings the price down a bit... and getting a teleconverter 1.4x and 2x helps though they can soften the focus a bit and reduce the light by a half stop to a full stop, with fast primes I haven't found this to be a limitation.

Reilly

Mountain climber
The Other Monrovia- CA
Dec 28, 2012 - 07:43pm PT
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?
Ed Hartouni

Trad climber
Livermore, CA
Dec 29, 2012 - 04:00pm PT
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 0.29 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 0.0037/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!

Ed Hartouni

Trad climber
Livermore, CA
Feb 18, 2013 - 12:18am PT
it's that time again, and weather will be a consideration...
there are three days:

Fri 2/22, moon rise: 15:13, azimuth 71.15
Sat 2/23, moon rise: 16:21, azimuth 75.55
Sun 2/24, moon rise: 17:21, azimuth 80.77

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.


Dingus Milktoast

Gym climber
And every fool knows, a dog needs a home, and...
Feb 18, 2013 - 12:23am PT
The stone fruit blossoms are opening too. Hope it works for you!

DMT
Ed Hartouni

Trad climber
Livermore, CA
Feb 23, 2013 - 12:09pm PT
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...
climbski2

Mountain climber
Anchorage AK, Reno NV
Feb 23, 2013 - 12:17pm PT
The intersection of astronomy and surveying is making for a compelling photographic discipline! Hopefuly the meteorology will cooperate. Good luck!
Reilly

Mountain climber
The Other Monrovia- CA
Feb 23, 2013 - 12:38pm PT
Too bad you don't have the new Nikon 800mm- it would be perfect! ;-)
Banquo

climber
Amerricka
Feb 23, 2013 - 02:23pm PT
Good luck. I'll be in SF having dinner with my kid.
Ed Hartouni

Trad climber
Livermore, CA
Feb 24, 2013 - 12:36am PT
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.
john hansen

climber
Topic Author's Reply - Feb 24, 2013 - 12:42am PT
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.
Mike Bolte

Trad climber
Planet Earth
Feb 24, 2013 - 01:06am PT
Ed - this is a lot of fun to follow your thinking and efforts!
mouse from merced

Trad climber
The finger of fate, my friends, is fickle.
Feb 24, 2013 - 11:16am PT
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.
Credit: mouse from merced
Messages 141 - 160 of total 178 in this topic << First  |  < Previous  |  Show All  |  Next >  |  Last >>
Return to Forum List
Post a Reply
 
Our Guidebooks
Check 'em out!
SuperTopo Guidebooks


Try a free sample topo!

 
SuperTopo on the Web

Review Categories
Recent Trip Report and Articles
Recent Route Beta
Recent Gear Reviews