Astronomy and DSLR Astrophotography Blog

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This a list some of the more common celestial terms and objects that you may wish to learn how to find, look at with your telescope and eventually create an image for.

Asterism -is a clear, recognizable pattern or a shape found in the sky that is formed by a group of stars that is smaller in area than a constellation.

Comet – is a small celestial body composed of ice and dust and can be found orbiting the Sun on an elongated path. When a comet’s orbit is closere to the Sun, a long gas and dust tail is produced due to evaporating ice.

Conjunction – is the moment when two celestial objects can be found very near to each other in the night time sky.

Constellation – is any one of 88 official star patterns. Most are seen either in the summer sky or winter sky.

Double Star – is when two stars appear close together in the sky. Some are just chance alignments as seen from Earth, Others are binary systems where stars will orbit each other.

Galaxy – is a huge collection or gathering of stars, gas,and dust that gravity binds together.. Galaxies are categorized by their shape: spirals, barred spirals, and ellipticals. About 75% of the brighter galaxies we see in the night sky are are spirals.

Globular Star Cluster – is a tightly-packed spherical cluster that may have up to a million older stars. Globular clusters are found in a halo that surrounds the Milky Way Galaxy.

Light-year – is the measurement term used to describe the distance that light travels in one year. One light- year is equal to six trillion miles. With the vastness of the known universe, distances to celestial objects are measured in light-years.

Lunar Eclipse – is when the Earth’s shadow crosses the face of the Moon. This causes the Moon togradually darken, and then lighten over the course of an hour or two. A partial lunar eclipse is when due to the location part of the moon is covered by the Earth’s shadow. This can be seen with the naked eye.

Magnitude – is a number used to describe the level of brightness of a each star giving a way to measure the relative brightness. A first magnitude star is the brightest category and is about two and a half times brighter than a second magnitude star. About 20 stars are considered first magnitude . Human eye can typically see stars as faint as sixth magnitude without a telescope

Messier Object List – is a master list of 110 star clusters, nebulas, and galaxies that were compiled by Charles Messier , who was an 18th century comet-hunter. On star maps, you will find they are specified by the letter “M” followed by the object number. For example, the Orion Nebula would be listed as M42.

Meteor – is a bright streak of light in the sky that is produced by a piece of debris called a “meteoroid.” Traveling at a high rate of speed, it will burn up as it enters Earth’s atmosphere Meteors are commonly referred to as “shooting stars,” even though they are not even close to being a star.

The Moon – is 239,000 miles from Earth and is its only natural satellite. The Moon revolves around the Earth every 27.3 days and since it also rotates once every 27.3 days, we never see its far side. The Moon’s phases are based on its location relative to the Earth and the Sun.

Nebula – is a cloud of gas or dust in space. “Reflection” nebulas, are those where starlight reflects off the nebula’s dust.. “Emission” nebulas, are where the cloud itself emits light because its atoms are affected by a lot of nearby hot stars. Nebulas are essentially giant star-forming factories.

NGC Object List – is the “New General Catalog.” which is a list of deep sky objects first published in 1888 For the most part, NGC celestial objects are fainter than the Messier objects.

Open Star Cluster – is a group of a few hundred stars, bound together by gravity, and moving through space together. Open star clusters are generally found closer to Earth than the globular clusters. These stars are considered to be much younger.

Opposition – is the point in a planet’s orbit when it appears to be opposite the Sun. When a planet is in its opposition point, it can be seen in the night sky from dusk till dawn.

Planetary Nebula – is a shell of gas that late in the life of a star will be puffed off by the star life. It sometimes looks like a ring, as if the gas is wrapped around a central star.

The Planets – According to the International Astronomical Union the definition is a spherical object orbiting the Sun with sufficient mass to have its own gravity, and a clear neighborhood around its orbit. There are 8 planets in our solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Pluto is now considered a “dwarf planet.” Other dwarf planets include a newly discovered object called “Eris” found in the Kuiper Belt beyond Pluto and a former asteroid called “Ceres.”

Solar Eclipse – is a rare celestial event that happens whenever a New Moon passes directly between the Sun and the Earth. Solar eclipses can be total or partial. Total eclipses occur when the Moon covers the entire disk of the Sun. These should not be observed with the naked eye.

Stars – are enormous spheres of hot gas when hydrogen gas is fused to form helium. This is what generates light and energy deep within their cores. The temperature of a star varies with its color. Blue-white stars are the hottest, yellow-orange stars are moderately-hot, while red stars are the coolest. The closest star to Earth is our Sun( 93,000,000 miles) which is a moderately-hot yellow- orange star, whose surface temperature is about 11,000°F. The next closest star is over 4 light-years away, and.is called Alpha Centauri.

Sunspots – are dark, highly magnetized blemishes on the surface of the Sun,they are in reality cooler areas, about 1,500 Celsius degrees cooler than the rest of the Sun’s surface. An average sunspot is at as big as Earth. Some can grow to be up to10 times the size of the Earth.

Terminator – is the line separating sunlit reflection of day and shadow of night on the surface not the Moon or on a planet.

Transit – is an when Mercury or Venus (inner planets) passes directly in front of the Sun. With a properly filtered telescope, the planets own disk can be seen against the solar background as it transits or crosses the Sun’s disk. Transits are relatively rare occurrences.

astrophotography Beginning Astrophotographer Terms

#1: The more you magnify a celestial object, the field-of-view becomes narrower.

#2: A wide field-of-view will require less tracking with a telescope to pinpoint an celestial object than a narrow field-of-view.

#3: Even though your camera sensitivity will increase at higher ISO settings (ISO 400 and ISO 800), the graininess or “noise” is also increased.

#4: Light pollution or atmospheric turbulence is worst near the horizon. Plan night time imaging sessions when the objects appear high in the sky.

#5: Detailed and vivid lunar images are clearest during the quarter moon phase.

#6: Use the moons “terminator line,” the light dark shadow line, to photographs cratered terrain with some amazing 3-D detail!

#7: Highest quality deep space images are taken when the sky is darkest. The period just before the moon rises, or during the New Moon phase are two excellent times.

The theme for the budding night imaging hobbyist is practice and perseverance create proficiency. Imagine how time consuming this would have been with 35mm film! The digital camera opens the doors for many more people to get involved in photographing the interesting objects found in the night sky.

The more you practice, you should be able to see the improvements, which will provide the motivation to continues on and create some of the most beautiful images you can imagine.

If you choose to advance to the astrophotography techniques levels using a telescope it will be helpful to first practice and enjoy just plain stargazing without any imaging . Learn to use the telescope and its features and learn to read the star charts, maps and get some good astronomy guidebooks. Make sure you have some pictures other people took to use as a guide when identifying what you find. By taking the time to have a better understanding of the night time sky, you will be able to make better decisions when beginning your astrophotography adventure.

This hobby can be a lot of fun, and is easily one that can be shared with others. Star gazing and imaging parties on key dates when certain celestial objects are in the right spots can be an enjoyable way to learn new tips and share your enthusiasm. Then again, a nice summer evening in your back yard, looking for Saturn’s rings can be a relaxing way to wind down at the end of a long day.

astrophotography astronomy guidebooks, astrophotography techniques, star charts, Star gazing

This is an interesting distortion that makes a photograph look as if you were looking through a long tube, like a straw. It is due to the fact that the circle from the end of the telescope tube can be seen surrounding the celestial image.

You can deal with vignetting in two different ways.

1. One is with a bright object. You can try to use the zoom feature to enlarge the object to the point where the circle is out of the view range of the camera. This will not work so well with a faint object as the magnification makes it even dimmer.

2. For those celestial object that are faint, you can try to remove the “vignetting” as part of the processing of the photographs on the editing software you use. With some perseverance and practice it can be done by learning how to adjust the sky levels, keeping uniformly dark background sky, yet getting rid of the circle.

astrophotography Vignetting

Some magnification is needed for all deep sky objects, and even with a top notch electronic tracking system, there will still be some star distortion caused by the earth’s rotation. Since you are using the longer exposure settings, and a point-and-shoot camera, it cannot be helped. It can be minimized a bit. What you do is shorten the exposure period a little, down to 50 seconds. Keep going lower until the star is seen as a pin point. It will take many practice shots to get the balance between exposure and the distortion just right. Some people have taken beautiful shots with the star trailing that has its own beauty. But your goal is to get as clear a shot as possible.

astrophotography Star Trailing

You use an entirely different approach to astrophotography when you want to capture images of objects further away and way and out of the range of the naked eye. The Great Orion Nebulae is one of the more famous of these objects.

Deep sky objects logically are very faint as they are much further away than the planets. This means that the light sensors will need to collect information over a much longer period of time time before the celestial object will be able to be seen in a photograph. This can be difficult with point-and-shoot cameras as the maximum exposure time is 60 seconds. The DSLR camera will be better suited for gathering images of these deep sky objects. This is a sign of a very serious hobby, indeed.

The beginner should not despair or go into serious debt at this level. There are plenty of celestial objects that can be photographed successfully using the point-and-shoot camera and eye-piece projection techniques. You will need to be sure to have a guidescope or off-axis guider, as explained earlier, that uses a GPS technology to keep an image in the center of the eyepiece of a long time thus letting you apply some more sophisticated imaging techniques.

Insight into Low-cost, Non-technical Methods for Celestial Objects at Great Distances-

You will have to find a location for this effort that has as dark a sky as possible. This will give you the best chance for getting a photograph of these fainter or deep sky objects as there will be some contrast to work with between the dark sky and the celestial object. One trick is to use the New Moon phase when the sky is naturally darkest. If you live in an area with high light pollution, you might want to find a friend or vacation spot with darker skies.

Once you have a good location, you use your telescope with the camera attached to the eyepiece. When you have found the location of the celestial object you were looking for, and focused it and set the tracking, you tehn will go an .adjust the cameras settings as described below. This will give you the best light-gathering options

• Sensitivity – ISO 400, SHQ (Super High Quality) setting, Macro or Infinity setting,

• Exposure range – 60 seconds,

• Aperture – f2.8 or lower.

• Set self-timer for a ten second delay to avoid any camera shaking possibilities

• Optional: Add a Barlow lens to the eyepiece in front of the camera. This lens only works with the brighter objects as it doubles the magnification of any eyepiece attached to the telescope. It will just make the fainter objects dimmer.

The two primary challenges of deep sky imaging with eyepiece projection:

“star trailing” and “vignetting.”

astrophotography Deep Space Objects

Using Level Three eyepiece projection will bring the craters of the moon and the rings of Saturn to life , and if that is not exciting, you are researching the wrong hobby. Most people are simply not prepared for the clarity and 3D look of the moon’s crater, or of the color found of the rings of Saturn.

The first problem that many find when taking pictures of the moon, is that what is seen through the telescope’s eyepiece does not match in clarity to what shows up on the camera’s LCD screen. A vivid view through the telescope will turn into an average image on the camera.This is due to the turbulence in the Earth’s atmosphere. Timing photographic session with the moon at the highest points in the night sky helps eliminate some, but not all of this fuzziness.

The way to eliminate this is to use the “video” feature available on most cameras these days. Use the 10x zoom magnifying on the LCD screen. Set the ISO to 400 and get the telescope focused on the planet. Set the video to last for about 45 seconds. This is the equivalent of taking individual photos at around 15 frames per second. This can be done with a self-timer. When the video is watched on the camera, it will look as if the fuzziness is still there. However, when downloading the video to an editing “image stacking” software, the best of the 900 or so individual frames can be pulled out and then aligned exactly to the same position and let the software stack the photos. It is able to stack each frame in layers to produce one, sharp, clear, distinct image. With the fast shutter speeds of the video clip, there will be plenty of images without the distortion of the atmosphere mixed in with the rest of the photos.

Moon photographs

• Take at the highest point in the sky

• Take photos when moon is at or near its first phase.

• Lunar craters and mountain ranges take on a three-dimensional appearance

• The brightness of a full moon will be counterproductive to any detailed moon surface photographs

• Find the Terminator line, and take images close by.

 

Planet photographs-

Start with Saturn and Jupiter

• Saturn ’s rings

• Jupiter has colorful cloud bands and the Great Red Spot, which actually is an immense oval hurricane in the atmosphere

• Jupiter’s has four Galiean moons that are constantly changing positions and fun to capture their images

astrophotography Photographing the Moon and the Planets

This level is for those who are interested in getting some highly magnified images and for deep sky images, those objects not normally seen with the naked eye. For this type of astrophotography the digital camera is actually connected to the eyepiece of the telescope using an adapter specifically designed for this that will hold the camera firmly to the telescope.

First of all this will enhance the view of the moon and planets. Clear details of the moons’ craters and magnified views unimagined ever before of the planets are now available.

Since only the smallest portion of celestial objects in our universe can be seen with the naked eye, this level of astrophotography opens up the world of astrophotography to new levels with beautiful nebulae, global star clusters that were simply invisible to you before.

equipment Eyepiece Projection Imaging

This level takes you a step further, by adding the use of a telescope. Many night imaging hobbyists never go beyond the first level, they achieve great satisfaction with what they can accomplish. However there are plenty who get hooked at the first level and wish to move to the next step.

It is called piggy back mount because you take your digital camera and mount it on top of a telescope with a special adapter that will create a firm, rigid connection. What this does is let you use the telescope to track the item you want to photograph, Once you found it, then you will see it in the LCD screen on the camera. When you are ready, you take the picture.

What you can do, that can’t be done in Level One, is actually use the internal tracking mechanisms of the telescope to keep the image centered. This lets you take exposures up to 60 seconds ( level one 30 seconds was the limit). In addition, if the camera has a zoom lens, that can be used for magnifying the object before taking the picture without losing the quality of the image.

Become familiar with a monthly star map, as they will tell you when interesting patterns are due to show up and help you find where in the sky to look

Celestial objects to try to photograph

Wide fields of star clusters that do not normally fit into a telescope lens. The camera will be able to see the entire formation of spread out stars, and even magnify them, whereas the telescope eyepiece can see small portions.

Constellations

The Double Cluster

Pleiades (Seen Sisters) star cluster.

Combinations of planets and stars near the Moon

Challenge: the Milky Way – if you find yourself in an area with a very dark sky and no glow on the horizon from a city or town

Moon rising over a lake or mountain

Constellations like Ursa Major (The Big Dipper), Orion the Hunter, Scorpius the Scorpion, and Cassiopeia the Queen.

Look for these objects when they are suspended over a picturesque background

equipment Wide-field Imaging With a Piggyback Mount

This level is simplest and the least expensive. It is not hard to master the techniques, making the rewards come quickly. It also involves the least amount of equipment. It is one of the best ways to experiment with your camera’s settings, not to mention familiarize your self with the parts of the camera’s owners manual you have ignored in the past. It is the perfect way to get used to the concepts of astrophotography before graduating to more difficult levels.

The only equipment needed is a digital camera mounted to a sturdy tripod. The very beginner can even use a bean bag on their car’s roof instead of a tripod!

These photographs will generally be a wide view of a starry sky, constellations or a moon that is framed against a scenic landscape as a back drop. Due to the wide-field, these images will have no blur or star trailing, provided the shutter is open 30 seconds or less. This is due to low magnification and the widest field of view. The limited capabilities actually work for you, making it harder to mess up.

Photography Tip:

Try using your digital camera mounted on a tripod at that special time of night that is right after dusk as the stars are just beginning to appear. Your camera’s light sensors should be sensitive enough to capture the stars , while still having enough natural sky-glow to include scenic foreground images like a line of trees, or a mountain, or a recognizable landmark. This adds some depth to the photograph and the landmark images give it a more interesting visual look.

Recommended Settings for Level One Night Sky Imaging:

• lower sensitivity- reduces or eliminates noise levels

• noise reduction settings- should turned on. Some cameras have them, others do not.

• Experimentation for each type of object, the moon, a planet, a favorite constellation- With ISO setting experimentation, you quickly get the chance to figure out the best “starter” settings for each type of celestial object. Then you can easily make minor adjustments that are based on time of night, light as a result of phase of the moon, and weather conditions.

equipment Wide-field Imaging with a Tripod

You are a beginner astrophotographer if:

-You enjoy keeping track of some of the things in the night sky

-You had a night sky poster over your bed that you bought yourself and was not a gift from well meaning Aunt Matilda so your mother made you put it up there

-You go out an watch when you find out there is an eclipse, or three planets lining up in a row, or when a once in a lifetime comet or meteor is scheduled to go by

-However: the only camera setting you use is Auto

-However: the only telescope you ever used is one you hold in both hands and move the eyepiece in and out to focus

You can be sure that any of the beautiful celestial images you see online, or in astronomy books were probably one of a hundreds of images taken, each one trying different settings, and minor adjustments here and there until the perfect shot was found. This is the way of an astrophotographer!

With the digital camera, you instantly see if your image works, and can delete it and try again with minor adjustments here and another one there. Over time, you will learn the best settings to begin your night time imaging sessions with, but to help you out, there is a discussion of each of the three levels of astrophotography that are best suited for a back yard hobbyist. There will be some photography tips along with some initial camera setting ideas to use as a starting point. It might be wise to include bug spray in your equipment list!

astrophotography beginner astrophotographer