Doing it in practice

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We orient ourselves at a real place lying before us

Where I live, there is a church with two beautiful towers standing parallel to each other. I have been imagining for some time a picture where the sun is directly above the two towers. I also knew the exact location from which I wanted to take the picture, ensuring that the foreground was appropriately framed. On a free afternoon, I went to this place in order to catch up with the compass and the inclinometer to the appropriate values.

A mirror compass is the most suitable for our task of determining the azimuth angle, as it enables us to accurately locate an object in the field while simultaneously monitoring the magnetic needle and recording the course. Of course, you can do much more with a good compass, but that’s all we need. We either take a bearing on the spot in the sky where we would like the sun or moon to be, or the one we want the sun to shine on from a certain direction, wait for the compass needle to settle to the north, and twist the compass box until 0° comes to rest at the north point of the needle. The azimuth angle facing the bearing mark is then the value we continue to calculate with, effectively our heading. In this way, I measured an azimuth angle of 70° and an elevation angle of 15°. The Astrocalc software, a very good freeware, processed these data along with the longitude and latitude for Bielefeld (52° northern latitude and 08° eastern longitude) and showed that the sun takes the desired position annually on May 20 around 07:00 local time. This is not self-evident, because the azimuth values for sunrise and sunset as well as for moonrise and moonset for each geographical position vary only within a certain range. For instance, in Bielefeld, the azimuth values range from 49° to 128° for sunrise and from 311° to 232° for sunset. Anyway: Getting up early is not my thing, but in this case I did it, and it was worth it.

We orientate ourselves at a place lying in front of us on the map

Several years ago, while visiting Arches National Park in the US state of Utah, I took a wonderful picture of the Windows Section bathing in the grazing light of the setting sun. The windows are openings eroded into the soft sandstone typical of this area. Unfortunately, a foolish mistake irreparably damaged the slide, but I would like to try it again and improve it on a future trip: this time, the sun should be directly opposite the subject.

I use the official park brochure’s map of the area for planning purposes. On it I put the compass parallel to the map edge or a vertical grid line over the planned shooting location, here the Petrified Dunes Viewpoint, turn the compass box until N(orth) points exactly upwards according to the northing arrow on the map (maps are usually oriented, that means their upper edge is at the same time the north direction) and read off the azimuth angle of 50° pointing to the Windows Section motif. However, since I want the sun to be in the exact opposite direction for the new exposure, I added 180° to this value and thus get the azimuth of 230° necessary for the input into the program. An online database quickly provides the longitude and latitude data for Arches NP (38° North, 109° West), and experience reveals that the sun emits the desired red-heavy warm light at an elevation angle of 5° to 10°. The program Astrocalc calculates all data to a date of December 4, around 16:00. – Unfortunately, no winter trip to Utah has occurred yet!

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