A Celestial Angel's Landing

[LittleMike]

Here's my week 6 photo! There's a hike going to the top of this cliff face known as Angel's Landing, hence the name of the shot. C&C please!

Canon 5DmkII w/24-105L lens
f/5
37 min 54 second exposure
ISO 100

 

[amateuraperture]

Very nice shot!

 

[NikonNewbie]

That is fantastic...whats that at the top there? the swirls?

 

[sunlou]

cool

 

[jay125]

That is fantastic...whats that at the top there? the swirls?

Those are star tracks. Using a long exposure at night on a tripod will brighten the scene and also record the stars as the earth moves.

Great shot!

 

[tirediron]

Well captured!

 

[Shawnda]

That is fantastic...whats that at the top there? the swirls?

Those are star tracks. Using a long exposure at night on a tripod will brighten the scene and also record the stars as the earth moves.

Great shot!

Wouldn't this require for long exposure to be open for a very long time as the earth moves. As we know, it's not moving super fast. I would think that is an all night venture.

 

[OrionsByte]

That is fantastic...whats that at the top there? the swirls?

Those are star tracks. Using a long exposure at night on a tripod will brighten the scene and also record the stars as the earth moves.

Great shot!

Wouldn't this require for long exposure to be open for a very long time as the earth moves. As we know, it's not moving super fast. I would think that is an all night venture.

It moves a lot faster than you think. Even as little as a 30-second exposure will give you star trails (small, but noticeable).

Go outside right after it gets dark, find a constellation you recognize, and note its location in reference to a landmark or something. Then go out an hour later and look again. You'll be surprised how much it moved.

 

[LittleMike]

Jay and OrionsByte hit the nail on the head. They're star streaks from a single long exposure. If you really think about it, the earth makes one full rotation every 24 hours, meaning that each star would make a complete circle in that amount of time. So since the shutter was open for a little over half an hour, it would leave just over 1/48 of a circle. Looking at an individual streak, you can tell it is just a very small portion of a complete circle.

 

[OrionsByte]

Also, since he was facing north, you'll notice that the streaks towards the center of the spiral are shorter than the ones farther out. That's because the Earth's axis points almost exactly at the North Star, so from our perspective it doesn't move perceptibly at all ;that's why it's good as a guide star - it's always in the same place.

So the whole sky, including the sun, moon, and stars, all appear to rotate around the North Star (assuming you're in the northern hemisphere). Therefore, the closer something is to the North Star, the more slowly it will appear to move, because there is less "distance" for it to "travel" in 24 hours, and vice versa.

 

[Ron Evers]

Now explain how the rotation is centred over the pinnacle.

 

[quiddity]

how do you decide on a exposure length

great shot

 

[MCPorche]

Now explain how the rotation is centred over the pinnacle.

Locate your tripod in such a way that the North Star is directly behind the pinnacle.

 

[LittleMike]

how do you decide on a exposure length

great shot

Honestly, for me it's more just trial and error. I've done enough that I can usually guess pretty close. And when you're dealing with exposures that are that long, a couple of minutes one way or the other won't make a huge difference.