Getting Started in Astrophotography - Revision history

Jmh921: /* Altitude-Azimuth Mounts */

2020-01-20T21:15:39Z

‎Altitude-Azimuth Mounts

Jmh921: /* LEVEL 1 */

2019-09-26T19:20:52Z

‎LEVEL 1

Jmh921: /* Kinds of Astrophotography */

2019-09-16T23:28:17Z

‎Kinds of Astrophotography

Jmh921: /* Deep Sky Photography */

2019-09-16T23:23:31Z

‎Deep Sky Photography

Jmh921: /* Deep Sky Photography */

2019-09-06T14:12:53Z

‎Deep Sky Photography

Jmh921: /* Solar Photography */

2019-09-04T15:53:01Z

‎Solar Photography

Jmh921: /* Comet Photography */

2019-09-03T21:38:43Z

‎Comet Photography

Jmh921: /* Comet Photography */

2019-08-28T23:30:31Z

‎Comet Photography

Jmh921: /* Lunar Photography */

2019-08-28T21:45:36Z

‎Lunar Photography

Jmh921: /* Nightscape Photography */

2019-08-28T21:22:01Z

‎Nightscape Photography

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 The simplest type of mount motion is what is known as altitude-azimuth, or alt-az. Altitude refers to the angle above or below the horizon, while azimuth refers to the angle along the horizon, left or right. Azimuth measures usually are given between 0° and 90° Typically, the [[zenith]] is considered 90° altitude and the horizon is 0°. For Azimuth, 0° or 360° is typically due North, 90° is due East, 180° is due South, and 270° is due West.  Alt-az coordinates are relative to the observer's position, and for astronomical objects, they are relative to the observer's position on the Earth as well as the time and date of the observation.  If a person in New York sees Jupiter at an altitude of 60 degrees above the horizon, to an observer in Chicago, it would only be 45 degrees above the horizon at that time, but will reach 60 degrees about an hour later.
-Alt-az is intuitive for most people. We liver our lives in a left-right, up-down manner.  But for astronomy, this often presents problems.
+Alt-az is intuitive for most people. We liver our lives in a left-right, up-down manner.  But for astronomy, this often presents problems.  This is because we live on the surface of a rotating planet that is roughly spherical.  While objects in the universe do move, the rate of motion is typically very low, which means they don't appear to be moving at all from our vantage point over the course of minutes, hours, days, or even years.  If the Earth was not rotating or orbiting the sun and you were to look up at the night sky, other than things in our solar system, the positions of everything out there would not seem to change at all except over long periods of time.  But because the Earth is rotating at a rate of 1 rotation per day, from our vantage point it appears those objects are moving.
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 Level 2
 ===LEVEL 3===
 Level 3

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 On the other hand, objects with smaller angular measurements, such as most planetary nebulae and many galaxies, typically need more magnification.  This requires longer focal lengths and/or smaller image sensors.  This, in turn, decreases the width of the field of view, which puts greater demands on the mount's tracking accuracy.  Even with autoguiding, many mounts are simply not well suited to this task.
-=LEVEL 1=
+=Equipment=
-Level 1
-==LEVEL 2==
+For any kind of astrophotography, there are three main pieces of equipment needed:
 Level 2
 ===LEVEL 3===

← Older revision		Revision as of 23:28, 16 September 2019
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	==Kinds of Astrophotography==		==Kinds of Astrophotography==
		+
		+	====Star Trail Photography====
		+
		+	This has been a traditional starting point for many astrophotographers and has the least-demanding requirements. Typically all that is needed here is a camera which offers you the ability to capture long exposures and a tripod or some other mount to hold it still.
		+
		+	The bulk of star trail images are taken toward the pole, which shows the rest of the sky turning around the pole itself. Some nightscape images (see below) use star-trail images instead of fixed-star images.

	====Nightscape Photography====		====Nightscape Photography====

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 DSO targets include galaxies, nebulae, and star clusters.  Each of those can, of course, be sub-divided.
-The easiest overall division here to use is by [[Angular Measure]].  Targets which require a wider field of view (for example [[NGC]] 7000, the North America Nebula M31, the Andromeda Galaxy, and the Veil Nebula)
+The easiest overall division here to use is by [[Angular Measure]].  Targets which require a wider field of view (for example [[NGC]] 7000, the North America Nebula M31, the Andromeda Galaxy, and the Veil Nebula), typically require telescopes with shorter focal lengths, cameras with larger image sensors, and are less demanding on the tracking accuracy of the mount.
 =LEVEL 1=

← Older revision		Revision as of 14:12, 6 September 2019
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	====Deep Sky Photography====		====Deep Sky Photography====

		+	The biggest challenges in AP come with deep sky astrophotography, or DSO AP. There are two key inter-related reasons for this.

		+	The Earth rotates on its axis once every 24 hours. When you factor in the additional movement caused by the Earth's orbit around the sun, the actual apparent rate of motion of astronomical objects in the sky is about 4 minutes short of 24 hours. This is the [[sidereal rate]].

		+
		+	DSO targets include galaxies, nebulae, and star clusters. Each of those can, of course, be sub-divided.
		+
		+	The easiest overall division here to use is by [[Angular Measure]]. Targets which require a wider field of view (for example [[NGC]] 7000, the North America Nebula M31, the Andromeda Galaxy, and the Veil Nebula)

	=LEVEL 1=		=LEVEL 1=

← Older revision		Revision as of 15:53, 4 September 2019
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	====Solar Photography====		====Solar Photography====
		+
		+	Due to the intensity of the energy involved, solar photography requires some form of filtering to avoid damaging the camera and/or telescope. As with lunar and planetary imaging, exposure times are very short, so mount selection is far less critical. But the filtration option itself can be expensive, depending on the type of solar filtering used.
		+
		+	There are two main types of solar filters: so-called "[[White-Light Solar Filter\|White Light]]" filters and [[Hydrogen Alpha Solar Filter\|Hα filters]].
		+
		+	White-light filters are fairly inexpensive, but also show the least. A white light solar filter will allow you to see sunspots, transits, and possibly solar granulation (though not clearly).
		+
		+	Hα filters are a whole different ballgame. These combine an energy rejection filter with an etalon which allows for a very narrow bandwidth of light to be viewed. This allows the viewer to see a lot more detail at a specific wavelength of light. This allows the user to see things such as solar prominences (these are frequently, though incorrectly, referred to as solar flares, but flares are a much larger feature). There are other, similar filters for different wavelengths. Calcium K is the second most common such filter, though the vast majority of narrow-band solar filters for amateurs are Hα.

	====Deep Sky Photography====		====Deep Sky Photography====

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 There are actually two different kinds of comet astrophotography. The first kind is primarily used for discovering comets.  The other is to produce an image of the comet.
-Photography for discovering comets - which can also be used for discovering asteroids or even Kuiper Belt Objects (KBOs) and was also the technique used to discover Pluto - involves capturing multiple images of the same patch of sky over time. It can be done during a single imaging session or over several. The images are then compared in an effort to identify any objects that appear to move between the images.
+Photography for discovering comets - which can also be used for discovering asteroids or even Kuiper Belt Objects (KBOs) and was also the technique used to discover Pluto - involves capturing multiple images of the same patch of sky over time. It can be done during a single imaging session or over several. The images are then compared in an effort to identify any objects that appear to move between the images.  The discovery of Pluto utilized a device called a Blink Comparator, which rapidly shifted between images.  Today, typically images are merged and a moving object will show up in multiple positions, typically forming a line as it moves through the image.
 ====Solar Photography====

← Older revision		Revision as of 23:30, 28 August 2019
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	====Comet Photography====		====Comet Photography====
		+
		+	Comet astrophotography comes along with some unusual challenges.
		+
		+	There are actually two different kinds of comet astrophotography. The first kind is primarily used for discovering comets. The other is to produce an image of the comet.
		+
		+	Photography for discovering comets - which can also be used for discovering asteroids or even Kuiper Belt Objects (KBOs) and was also the technique used to discover Pluto - involves capturing multiple images of the same patch of sky over time. It can be done during a single imaging session or over several. The images are then compared in an effort to identify any objects that appear to move between the images.

	====Solar Photography====		====Solar Photography====

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 ====Lunar Photography====
 As the name suggests, this would be pictures of the moon.
 ====Planetary Photography====

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 File: Nightscape5.jpeg|07/24/2019|link=https://apod.nasa.gov/apod/ap190724.html
 </gallery>
 ====Lunar Photography====