APOD: Orion Over and Under Tibet (2015 Oct 05)

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APOD: Orion Over and Under Tibet (2015 Oct 05)

Post by APOD Robot » Mon Oct 05, 2015 4:06 am

Image Orion Over and Under Tibet

Explanation: This night was so serene you could see Orion rise downwards. The unusual spectacle was captured in this single-exposure image, featuring a deep sky around the famous constellation of Orion that appeared both above -- and reflected in -- a peaceful lake in the Gyirong Valley of Tibet, China. Taken last year at this time, the three belt stars of Orion can be seen lined up almost vertically above and below the Himalayan Mountains. The complex Orion Nebula can be seen to the belt stars' right, while the red-glowing circular structure surrounding Orion is Barnard's Loop. Also, the bright red star Betelgeuse is doubly visible on the image left, while bright blue Rigel appears twice on the image right. Familiar Orion is becoming increasingly visible as Winter (Summer) descends on the Northern (Southern) hemisphere.

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Re: APOD: Orion Over and Under Tibet (2015 Oct 05)

Post by Ann » Mon Oct 05, 2015 5:12 am

What a wonderful picture! Look how the lake not only reflects the stars and the nebulas but also enhances their colors. The Orion Nebula is two-colored in the watery reflection, white and a deep, saturated rose color. Betelgeuse is glowing like an ember and seems to be involved in some nebulosity too, although that must be caused by the slightly wave surface of the lake. In the "sky version" of Orion you can make out a little black protrusion that is the Horsehead Nebula. I can't see the Horsehead in the lake, but I can see its red nebulosity background.

That's a lovely image! Thanks so much, Jeff Dai!

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first

Re: APOD: Orion Over and Under Tibet (2015 Oct 05)

Post by first » Mon Oct 05, 2015 6:11 am

In the water, I see star trails. The stars in the sky are pinpoints. Is this truly a "single-exposure" image? The star trails in the water has me to believe there are more than one exposure in the image, but I could be wrong.

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Re: APOD: Orion Over and Under Tibet (2015 Oct 05)

Post by geckzilla » Mon Oct 05, 2015 6:27 am

first wrote:In the water, I see star trails. The stars in the sky are pinpoints. Is this truly a "single-exposure" image? The star trails in the water has me to believe there are more than one exposure in the image, but I could be wrong.
It looks typical to me. Water reflections in long exposures with stars always end up a little bit unlike what one might expect. If you look at enough of them then you'll realize that this appearance is normal. They can streak even when the water seems almost mirror-like and perfectly still.
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first

Re: APOD: Orion Over and Under Tibet (2015 Oct 05)

Post by first » Mon Oct 05, 2015 6:57 am

It looks typical to me. Water reflections in long exposures with stars always end up a little bit unlike what one might expect. If you look at enough of them then you'll realize that this appearance is normal. They can streak even when the water seems almost mirror-like and perfectly still.
There is too much of a variance from the stars in the sky compared to the stars in the water. When I shoot a scene with sky and water at night, I do get a mirror image, with the stars in the water, however, being somewhat fainter. I have done this for decades. I have never gotten pinpoints of light and star trails in the water.

Why are the mountains and cabin looking somewhat out-of-focus, and yet the stars are so crisp? I like the picture, but the statement of a single exposure doesn't ring true.

mickwilson

Re: APOD: Orion Over and Under Tibet (2015 Oct 05)

Post by mickwilson » Mon Oct 05, 2015 7:24 am

I, too, have my suspicions about the composition of this shot. Apart from the anomalies around the star trails, I also wonder why the images of the cabin and mountains have not 'smeared' as the camera tracked Orion.

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Re: APOD: Orion Over and Under Tibet (2015 Oct 05)

Post by Jeff Dai » Mon Oct 05, 2015 7:30 am

Ann wrote:What a wonderful picture! Look how the lake not only reflects the stars and the nebulas but also enhances their colors. The Orion Nebula is two-colored in the watery reflection, white and a deep, saturated rose color. Betelgeuse is glowing like an ember and seems to be involved in some nebulosity too, although that must be caused by the slightly wave surface of the lake. In the "sky version" of Orion you can make out a little black protrusion that is the Horsehead Nebula. I can't see the Horsehead in the lake, but I can see its red nebulosity background.

That's a lovely image! Thanks so much, Jeff Dai!

Ann
Thank you very much for your kindly words, Ann
I also surprise about the final result of this image, The Barnard's Loop in the reflections is beyond my imagination.
Thanks to the perfect sky conditions of Tibet and a little bit lucky without wind :ssmile:

Best regards,
Jeff

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Re: APOD: Orion Over and Under Tibet (2015 Oct 05)

Post by Jeff Dai » Mon Oct 05, 2015 7:45 am

Hi @first and @mickwilson

The image is achieved by the classical single exposure. I used a modified DSLR and the sky-glow filter to increase the nebulosity contrast.

Photo Details:
Camera: Canon EOS 6D DSLR (Astro modified);
Lens: Samyang 35mm f/1.4 AS UMC lens;
Equatorial mount: iOptron Skytracker
Filter: Astronomik CLS Filter + Cokin P820 Soft filter;
FocaI ratio:35mm; ISO: 5000; Aperature:f/2.2; Exposure time: 30s;

I just tracked the stars with full speed at only 30 seconds. So you can see the mountain and the house is not sharp, but almost acceptable.
As i track the stars above, the reflections of the lake must be startrails of 30×2 seconds.

Best regards,
Jeff

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Re: APOD: Orion Over and Under Tibet (2015 Oct 05)

Post by mfavret » Mon Oct 05, 2015 10:36 am

Thank you for the technical data.

On a french astro forum we discussed also if it is realy a single exposure (and if you used an EOS 6D or a Sony Alpha 7s with a greatest gain). Your answer is clear about that.

I have a Ioptron Skytracker too. For such a picture with both sky objets and landscape, why you didn't use the half-speed tracking ? It's exactely its main use : to share the blur between stars and landscape (but it's also usefull for time-lapse : to have a dynamic effect of sky objects moving within the frame when the frame is panning the landscape).

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Re: APOD: Orion Over and Under Tibet (2015 Oct 05)

Post by Jeff Dai » Mon Oct 05, 2015 3:07 pm

mfavret wrote:Thank you for the technical data.

On a french astro forum we discussed also if it is realy a single exposure (and if you used an EOS 6D or a Sony Alpha 7s with a greatest gain). Your answer is clear about that.

I have a Ioptron Skytracker too. For such a picture with both sky objets and landscape, why you didn't use the half-speed tracking ? It's exactely its main use : to share the blur between stars and landscape (but it's also usefull for time-lapse : to have a dynamic effect of sky objects moving within the frame when the frame is panning the landscape).
Hi Mfavret,

The skyglow filter will reduce half of the exposure, as u can the EXIF, the total exposure is very high.
So the shuttle speed is 30 seconds, This shuttle speed is too long for 35mm lens at Half speed.
And as you see, our focus is not the foreground, Right ?

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Re: APOD: Orion Over and Under Tibet (2015 Oct 05)

Post by geckzilla » Mon Oct 05, 2015 3:48 pm

Jeff, you could share the raw exposure if you want to clear things up for skeptical individuals. I know sometimes sharpening filters and other post-processing can give an artificial look to things. It looks clearly like a single exposure to me. If it happened to not be, I would have to commend you for your skills in combining the photos. ;)
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Re: APOD: Orion Over and Under Tibet (2015 Oct 05)

Post by mfavret » Mon Oct 05, 2015 4:06 pm

Ok Jeff.

But I use to compute the exposure time on a tripod without stars trails with an old equation of 24x36 film camera : Tmax = 500s / F (with F being the focal length in mm). My experience is that it is quite Ok with full-frame digital camera (I have a 6D too).

With 35mm, the result is about 14s. So I guess that with a half-speed tracking, 30s was possible (half-speed -> double time).

In my opinion, stars trails on the water aren't due to Earth rotation but rather to reflection on the small waves/ripples (as it is on clouds in the case of solar pilar). I made a lot of night pictures ("nightscape") by a pond and it always looks like that. If it was an effect of Earth rotatIon, they would not be such "vertical".
Last edited by mfavret on Mon Oct 05, 2015 4:16 pm, edited 1 time in total.

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Re: APOD: Orion Over and Under Tibet (2015 Oct 05)

Post by saturno2 » Mon Oct 05, 2015 4:13 pm

Interesting
Beautiful image.
The exposition is only one ( I think)

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Re: APOD: Orion Over and Under Tibet (2015 Oct 05)

Post by Chris Peterson » Mon Oct 05, 2015 4:27 pm

geckzilla wrote:
first wrote:In the water, I see star trails. The stars in the sky are pinpoints. Is this truly a "single-exposure" image? The star trails in the water has me to believe there are more than one exposure in the image, but I could be wrong.
It looks typical to me. Water reflections in long exposures with stars always end up a little bit unlike what one might expect. If you look at enough of them then you'll realize that this appearance is normal. They can streak even when the water seems almost mirror-like and perfectly still.
While I don't think we're seeing star trails here, but rather some kind of reflection artifact, it's worth considering that we should see star trails in reflections where the sky is being actively tracked. The reflection is a mirror image: the direction of star rotation is reversed. So if we're tracking the sky, the reflected stars will actually move through twice the angle we'd expect for the exposure interval- half of that from ordinary stellar rotation and half from the fact that we're tracking in the wrong direction.
Chris

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Re: APOD: Orion Over and Under Tibet (2015 Oct 05)

Post by jfgout » Mon Oct 05, 2015 6:36 pm

Hi agree with geckzilla. The best way to end the polemic is to share the raw image.

jf

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Re: APOD: Orion Over and Under Tibet (2015 Oct 05)

Post by Boomer12k » Mon Oct 05, 2015 6:50 pm

WOW, what a splendid shot!!!

My favorite Nebula, the Great Nebula in Orion, and you can see SOOOOO MUCH MORE!!!!

Awesome!

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Re: APOD: Orion Over and Under Tibet (2015 Oct 05)

Post by geckzilla » Mon Oct 05, 2015 10:31 pm

Chris Peterson wrote:While I don't think we're seeing star trails here, but rather some kind of reflection artifact, it's worth considering that we should see star trails in reflections where the sky is being actively tracked. The reflection is a mirror image: the direction of star rotation is reversed. So if we're tracking the sky, the reflected stars will actually move through twice the angle we'd expect for the exposure interval- half of that from ordinary stellar rotation and half from the fact that we're tracking in the wrong direction.
I agree, not star trails but the water being ever so slightly disturbed by a very low frequency wave.
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Re: APOD: Orion Over and Under Tibet (2015 Oct 05)

Post by Jeff Dai » Tue Oct 06, 2015 12:40 am

Hi,

Yes the best way is sending RAW to all, But it's a pity that i'am traveling at Tibet now, i can't offer at this moment.
For the startrails in the water. As you know Orion always comes up sideways(azimuth is close to 90 degree). That means the left in the water is nearly vertical and right is slant.

By the way, I don't care too much about every people believe or not. Maybe i need proud of myself, as i can do the impossible of some clever guys.

Best regards,
Jeff

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Re: APOD: Orion Over and Under Tibet (2015 Oct 05)

Post by BillBixby » Tue Oct 06, 2015 2:12 am

Arrrrrrrrr matey, The picture be wonderful. I would like to say many a similar scene has exposed itself to my eyes as I traveled the Pacific, Atlantic, Arctic and Med seas. Yes, I would like to say that. But I was in a submarine and didn't get to see the beautiful skies reflected in the ponds I was sailing. Thank you for sharing your experience of this scene with us. Safe travels and enjoy Tibet.

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Re: APOD: Orion Over and Under Tibet (2015 Oct 05)

Post by neufer » Tue Oct 06, 2015 2:41 am

Jeff Dai wrote:
I just tracked the stars with full speed at only 30 seconds. So you can see the mountain and the house is not sharp, but almost acceptable. As i track the stars above, the reflections of the lake must be startrails of 30×2 seconds.
geckzilla wrote:
Chris Peterson wrote:
While I don't think we're seeing star trails here, but rather some kind of reflection artifact, it's worth considering that we should see star trails in reflections where the sky is being actively tracked. The reflection is a mirror image: the direction of star rotation is reversed. So if we're tracking the sky, the reflected stars will actually move through twice the angle we'd expect for the exposure interval- half of that from ordinary stellar rotation and half from the fact that we're tracking in the wrong direction.
I agree, not star trails but the water being ever so slightly disturbed by a very low frequency wave.

The bright streaks are probably Jeff's
30×2 seconds = 15' arc star tracking trails.

But the long thin streaks (along more or less the same direction) are more likely to be reflections from a very temporary train of high frequency water ripples generated by Jeff himself (from approximately the opposite direction of Orion).
Art Neuendorffer

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Re: APOD: Orion Over and Under Tibet (2015 Oct 05)

Post by BillBixby » Tue Oct 06, 2015 6:05 pm

I agree, not star trails but the water being ever so slightly disturbed by a very low frequency wave.[/quote]

The bright streaks are probably Jeff's
30×2 seconds = 15' arc star tracking trails.

But the long thin streaks (along more or less the same direction) are more likely to be reflections from a very temporary train of high frequency water ripples generated by Jeff himself (from approximately the opposite direction of Orion).[/quote]

__________________________________________

Thank you, Neufer, for the information above.

The passage of any or every person leaves a ripple upon the surface and passage of time? I had not thought of how sensitive the Earth could be to our movements.

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Re: APOD: Orion Over and Under Tibet (2015 Oct 05)

Post by jfgout » Thu Oct 08, 2015 2:24 pm

Jeff Dai wrote:Hi,

Yes the best way is sending RAW to all, But it's a pity that i'am traveling at Tibet now, i can't offer at this moment.
For the startrails in the water. As you know Orion always comes up sideways(azimuth is close to 90 degree). That means the left in the water is nearly vertical and right is slant.

By the way, I don't care too much about every people believe or not. Maybe i need proud of myself, as i can do the impossible of some clever guys.

Best regards,
Jeff
Hi Jeff,

No worries. I guess you can always send a link to the raw image when you come back from your trip. I must say I was a bit sceptical at first when I saw your pictures, but after thinking a bit more and following some discussions on astronomy forums I now have very little doubt about the authenticity of the image. I'm still curious to see what the raw image looks like.
This image is kind of a shock for people like me who were struggling to capture Barnard's loop on film (I started astrophotography in 1997, when I was still a teenager and before I could afford a digital camera). Seeing the loop appear on a 30 seconds exposure + its reflection in the water is a shock, showing us how far technology has moved in the past ~15 years.

I'm still surprised that the editors selected this picture and not one of your beautiful milky way pictures for the APOD. I mean, this picture directly speaks to astrophotographers. It is a great illustration of the progress made in the field. But for the general public, this will probably simply look like a noisy, not really jaw dropping picture. On the other hand, some of your milky way shots are really jaw dropping, and would probably have a great reception on the APOD. Just my 2 cents...

Hope you have a safe trip and bring back some more amazing pictures!

jf

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Re: APOD: Orion Over and Under Tibet (2015 Oct 05)

Post by geckzilla » Thu Oct 08, 2015 4:22 pm

jfgout wrote:I'm still surprised that the editors selected this picture and not one of your beautiful milky way pictures for the APOD. I mean, this picture directly speaks to astrophotographers. It is a great illustration of the progress made in the field. But for the general public, this will probably simply look like a noisy, not really jaw dropping picture. On the other hand, some of your milky way shots are really jaw dropping, and would probably have a great reception on the APOD. Just my 2 cents..,
Using Facebook reach as a metric for what the general public thought about this image (more shares means they liked it more) this image received more reach than any other image for the week and so far this month. People loved it!
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Re: APOD: Orion Over and Under Tibet (2015 Oct 05)

Post by jfgout » Thu Oct 08, 2015 9:06 pm

geckzilla wrote: Using Facebook reach as a metric for what the general public thought about this image (more shares means they liked it more) this image received more reach than any other image for the week and so far this month. People loved it!

Woa, that's a surprise for me! Thanks for the info.

jf

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Re: APOD: Orion Over and Under Tibet (2015 Oct 05)

Post by geckzilla » Thu Oct 08, 2015 9:12 pm

jfgout wrote:
geckzilla wrote: Using Facebook reach as a metric for what the general public thought about this image (more shares means they liked it more) this image received more reach than any other image for the week and so far this month. People loved it!

Woa, that's a surprise for me! Thanks for the info.

jf
It often surprises me, as well. Supermoon Total Lunar Eclipse got three times as much reach as this one. Anything with lightning in it seems to perform strangely well, especially volcanic lightning storms! I think if we had a mission to Io and captured some close ups of its volcanic activity we'd break APOD.
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