Can you see star-trails rotating both directions in the same picture?

[StarsWorld]

Hi,

If I understand it right, when you look to the north night sky you will see star-trails turning around in one direction, and when you look to the south night sky you will see star-trails turning in the opposite direction.

How can it be that in the following pictures (don't remember where I found them) you see star-trails turning both Clockwise & Counterclockwise in the same picture?

(including the centers of the rotation!)
 

 

 

Is it even possible?

Shouldn't each center be at totally opposite direction? One in the North and one in the South?
How can it be that you see both of them in the same field of view?

Thanks.
 

[Elp]

They're not singular pictures.

[StarsWorld]

Just now, Elp said:

They're not singular pictures.

Can you please explain?

It looks like a single picture to me.

 

[Elp]

To me it looks like a composite of at least four images. The north and south star trails have been taken over a few hours each with a star trail time lapse mode in camera with possibly another in the middle of them to blend them together. The foreground is a panoramic stitch of over 180 degrees which most mobile phones have a built in mode for. In software it's all been combined to look as one.

[Elp]

I'd say they've also used some sort of stitching software due to the star trails not being uniform arcs and have been distorted to get the straight horizon field of view once combined. If you look up star trail images, they're usually leave perfect circle paths.

Edited February 8 by Elp

[Xilman]

Yes.

Think about it.

Point a very wide-angle lens at the celestial equator. Wait.  Those star with positive and negative declination will circle their respective celestial poles.

[StarsWorld]

4 minutes ago, Elp said:

I'd say they've also used some sort of stitching software due to the star trails not being uniform arcs and have been distorted to get the straight horizon field of view once combined. If you look up star trail images, they're usually leave perfect circle paths.

If it's really kind of a panoramic image, of lets say 220 degrees, shouldn't we see the view distorted and squashed in the horizontal direction? I look at the trees, and the buildings in the background and they looks completely normal to me...
 

[Bugdozer]

1 minute ago, StarsWorld said:

If it's really kind of a panoramic image, of lets say 220 degrees, shouldn't we see the view distorted and squashed in the horizontal direction? I look at the trees, and the buildings in the background and they looks completely normal to me...
 

No. Panoramic images don't squash more in one direction than another, that's why their aspect ratio is elongated. 

[Elp]

The horizon is distorted, you can see it undulating up and down as you normally see in wide angle panoramas which haven't been corrected well, there's also slight pincushion type distortion where each panorama shot starts and ends and joins another. The trees aren't distorted because as I said, it looks like a panorama, multiple images taken horizontally and stitched together via software. If you took this with one lens, well I don't think such a lens exists that can take it as it's presented (well all sky lenses are quite wide but you get a fisheye effect if going too wide, say under 9mm focal length), but you'll have massive distortion at the edges which software is needed to sort.

Edited February 8 by Elp

[vlaiv]

That is quite normal if done with very wide lens - fish eye type that captures more than 180 degrees in single go.

Maybe simplest explanation would be using your own hands.

If you circle with both of your hands in the same direction (like gym exercise), here is drawing of what I mean:

say that you move them in "forward" direction (like butterfly swimming technique) - that is exactly how stars move in north and south hemisphere. They perform large circles - but in reality they circle in the same direction (because it's the earth that is spinning).

But if you look at your left hand while doing this - it will look as if it's circling clockwise and if you turn your head to the right to observe right hand - it will look like it's spinning counter clock wise.

Above images are simply done with lens that can "look at both hands at the same time" - meaning it has more than 180 degrees field of view.

[The Admiral]

Surely it doesn't really matter whether it's a very wide angle lens or is multi-panel mosaic, so long as both celestial poles are in the image.

Ian

[vlaiv]

5 hours ago, The Admiral said:

Surely it doesn't really matter whether it's a very wide angle lens or is multi-panel mosaic, so long as both celestial poles are in the image.

Ian

I guess that continuity of star trails would be giveaway, or rather which stars made which segment of circle.

With panoramic mosaic you need to capture separate parts and combine them - but you can't do that at the same time.

 

[uk_friendly_fire]

I'd guess it's a 360° camera time lapse. A clever idea

[Elp]

It's a composite as I've said. If you time lapse the foreground will be blurred and likely overexposed.

[The Admiral]

9 hours ago, vlaiv said:

I guess that continuity of star trails would be giveaway, or rather which stars made which segment of circle.

With panoramic mosaic you need to capture separate parts and combine them - but you can't do that at the same time.

 

Ah yes, hadn't thought of that.

7 hours ago, Elp said:

If you time lapse the foreground will be blurred and likely overexposed.

The camera will be static so the foreground shouldn't be blurred, but I guess overexposure might be an issue.

Ian

Edited February 10 by The Admiral