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tivoli_mike

Cool Position of the Sun photos...Analemma

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From spaceweather.com

 

 

If you took a picture of the Sun at the same time each day, would it remain in the same position? The answer is no, and the figure-8 traced out by the Sun over the course of a year is called an analemma:

 

The analemma above was created by Iranian astronomer Mohammad Reaza Noroozi. Using a single piece of film, he painstakingly photographed the sun on 45 mornings spanning two years, 2003-2005. The picture was completed with a single exposure of the foreground, a beautiful building in Tehran.

 

The upper and lower tips of the "8" represent the solstices--the longest and shortest days of the year. Midway between the tips are the equinoxes--when day and night are of equal length. The autumnal equinox, marking the beginning of northern autumn, was yesterday, Sept. 22nd. noroozi1_strip.jpg

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Hah! yellaf.gif I didn't even consider that before clicking. I guess it's all in how you mentally "say" it.

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That is, indeed, a beautiful building. Beats Frank Ghery all to hell. I wonder if HRoark would have liked it?

 

The photographer would have to use a very slow film, small aperture and very short exposure times. Imagine how much light he's having to deal with!

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I was wondering the same thing.

I think if he really did use one frame, each one would be really really dark. seems impossible.

If that really is how he did it, that's some good technique.

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If I was going to try it, I'd simply check the exposure for one shot and then divide it by the number of images I wanted to superimpose. Then at each time point, I'd take about 4 or 5 different exposures (on different frames).

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If I was going to try it, I'd simply check the exposure for one shot and then divide it by the number of images I wanted to superimpose. Then at each time point, I'd take about 4 or 5 different exposures (on different frames).

 

What else is amazing about this photograph is that is was sunny and clear every single day he took a picture!!

Also, did he mark the ground with tape? He got the tripod in the EXACT same location every single day?

SO many questions from one photo...

Still, it's a great shot.

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First off he lives in Tehran where it is sunny and clear most of the year - unlike Seattle.

 

Second of all he probably took those photos from his balcony or something. Just leave tripod standing.

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Photoshop not required. I have an astronomy book with the same sort of photo taken in pre-photoshop days.

 

The vertical axis of the analemma is due to change in the sun's declination (height above the horizon) related to the seasons. The horizontal axis is due to changes in the average length of the solar day, which is a function of how close the earth is to the sun in its elliptical orbit. This phenomenon is called the Equation of Time.

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A quick google search for equation of time resulted in this little gem. About halfway down the page it talks about the equation of time. At two-thirds down the page, the "figure 8" or analemma, is discussed under the inclination of the ecliptic section. The whole page is an interesting read. It's all good!

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The dots, I assume, are pictures of the sun?

If so, what is causing the tree in front of the building to cast a shadow to viewers left?

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You must have missed this part:

 

The picture was completed with a single exposure of the foreground, a beautiful building in Tehran.

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Presumably right at the equator the top and bottom of the 8 are equally sized?

 

And at the North Pole, you would only see half the 8, so it would look like a o balanced on the horizon.

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Presumably right at the equator the top and bottom of the 8 are equally sized?

 

And at the North Pole, you would only see half the 8, so it would look like a o balanced on the horizon.

 

The analemma has the same shape from any viewpoint on Earth, but at the poles it would be partly hidden. The place where the lines cross is not at the equinox, or even in the center of the axis. I tried to attach a scanned page but I'm still clueless how to do it.

Edited by Norman_Clyde

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But is it upside down in the Southern Hemisphere, at least, like the Moon?

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If I were to do this, what I would do is to:

 

a) take a picture of the scene without the sun in the image. taking pictures directly into the sun often results in a fair deal of flare and also creates deep shadow areas. clearly, from this picture, the sun is above and to the right of the building.

 

b) take a series of pictures of the sun, exposing it to be about zone viii using the and the shortest exposure time possible. this should keep the amount of additional exposure from the building and any surrounding scenery, esp clouds, from building up any density on the negative.

 

a similar sort of procedure is done with evening shots with a properly exposed moon in the sky.

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