EAA, Video Astronomy, ...

Definitions - Collection | My Own Attempt at a Definition | Experiences - Collection | Some Collected Questions and Answers... | Preliminary Conclusions | Links

On this page, I present some information about EAA (Electronically Augmented Astronomy), EAO (Electronically Augmented Observation/Observing), and Video Astronomy (as well as some related concepts).

See also page Atik Infinity Colour Camera - Experiences and page Motivation and Introduction.

 

Definitions - Collection

Below I present some definitions of video astronomy (or descriptions, what that is...) that I found on the Internet.

Wikipedia: Video Astronomy

Video astronomy is a branch of astronomy for near real-time observing of relatively faint astronomical objects using very sensitive CCD or CMOS cameras. Unlike lucky imaging, video astronomy does not discard unwanted frames, and image corrections such as dark subtraction are often not applied, however, the gathered data may be retained and processed in more traditional ways. Although the field has a long history reaching back to 1928 with the inception of live television broadcasting of the planet Mars, it has largely been developed more recently by amateur enthusiasts and is characterized by the use of relatively inexpensive equipment, such as easily available sensitive security cameras, in contrast to the equipment used for advanced astrophotography.

By using either the method of rapid internally stacked images, or very short exposure times, and using a TV monitor (for analog cameras) or a computer with readily available software (for USB cameras), video astronomy allows observers to see color and detail that would not register to the eye. Because the image can be displayed on a monitor or television screen it allows multiple people to share "live" images; using the Internet it is possible for a worldwide audience to share such images. Live broadcasting Websites exist for sharing live video astronomy feeds.

Video astronomy, combined with remote control of a telescope, allows anyone including disabled people to operate a telescope remotely, or observers in a light-polluted area to operate a telescope in another area, even another country.

Other benefits of the highly sensitive cameras used in video astronomy are the ability to see through thin clouds, and the ability to see many faint objects in areas suffering from light pollution. The equipment used varies from webcams and basic security cameras to specialized video astronomy cameras. Recent growing interest in the video "near-live" aspect of astronomy has brought about Websites devoted purely to the practice and forums for users of the equipment. (From Wikipedia, slightly adapted)

MallinCam: What Is Video Astronomy?

MallinCam is a manufacturer of cameras for video astronomy and defines it as follows:

A common problem plaguing amateur astronomers today is the prevalence of light pollution. The need to travel to a dark sky site in order to observe anything other than the Moon and planets makes it more difficult for amateurs to observe regularly. This also makes it difficult to encourage new people to join the hobby, especially young people. Video Astronomy has the ability to remove all these hindrances to observing from the city, opening up the hobby to everyone.

Most people are familiar with observing the night sky using a telescope. You simply put your eye to the eyepiece and let the scope focus the light directly into your eye, greatly magnified and brightened. Video Astronomy instead uses a camera to receive the light from your telescope. You then observe the resulting images live on a TV monitor or computer screen. The experience is just as "live" as if you were using an eyepiece, the difference being that a camera has some distinct advantages over the human eye:

(From: MallinCam Website, adapted)

Ken James: About Video Astronomy

The Solution

​The answer to poor visual situations or the need to switch to very long hours of astrophotography imaging to see anything is video astronomy, which could be refered to as something along the lines of "instant imaging." But video astronomy is not "imaging" as such. It is "electronically assisted observing (EAO)." Video astronomy is an aid, an assistance, an electronic visual tool. It brings astronomical objects to us in full color as close as possible to "instantly." It's like having a magical eyepiece that can see very faint objects, and in color.

Video Astronomy has many benefits over both 'Visual' and 'Astrophotography'

Some of the benefits of video astronomy are the ease at which the beauty of the night sky can be brought to wheelchair bound and other physically handicapped people, without having to struggle to get up to an eyepiece. Simply project objects onto a large screen for viewing by audiences at observatories and astronomy outreach events. And probably the most exciting of all is the ability to broadcast the view "live" on the Internet through Websites such as the "Video Astronomy Forum Broadcasts" and "Night Skies Network." And many video astronomers just like the instant gratification of seeing an object as near as possible to "live" in full color on their own TV, monitor, or computer screen.

(From: Video Astronomy by Ken James, adapted)

Brian Ventrudo: The Emerging Art of Video Astronomy

Astronomical video cameras give real-time, full-color views of deep sky objects with an amazingly high sensitivity that effectively triples the aperture of a small telescope, even in highly light-polluted skies. And these cameras provide an analog signal you can view with an off-the-shelf television or video monitor.

Alas, there are a few trade offs. The sensors in these cameras are quite small, about ½" on each side, which is typical for analog video. This does give a somewhat restricted field of view in a telescope. And the pixels in the sensor are relatively large, which is why they're intrinsically sensitive to low levels of light. Big pixels in a small sensor mean these cameras have low resolution, typically 640 × 480 or 720 × 480. That's still high enough to render a pleasing image, but it's far lower than the many megapixels available with the DSLRs or large CCDs used by the experts to capture the detailed images you see in Sky and Telescope or APOD.

(From: The Emerging Art of Video Astronomy, Part 1 by Brian Ventrudo, adapted)

Electronically Assisted Astronomy (Jarek Pillardy)

Electronically Assisted Astronomy (EAA) is a new branch of the hobby focused on real-time (or nearly real-time) viewing of astronomical objects (usually deep sky) with an aid of electronic devices. Typically there are 3 choices: video cameras, live stacking, and image intensifiers. Video astronomy is an easy way to EAA, with a moderate price tag, especially with the newest cameras.

(From: Electronically Assisted Astronomy by Jarek Pillardy, adapted)

Cloudy Nights Forum "EAA Observation and Equipment": Electronically Assisted Astronomy

Electronically Assisted Astronomy (EAA) is the use of a digital image capturing device in lieu of an eyepiece at the telescope.

(From: Cloudy Nights forum EAA Observation and Equipment; only visible in the Google search result for "Electronically Assisted Astronomy" and in the forum rules)

Fallenangel (Franz Müller): Electronically Assisted Astronomy with Atik Infinity

Electronically Assisted Astronomy (EAA) means here real-time (or nearly real-time) viewing of astronomical objects (usually deep sky) with an aid of electronic devices. (Typically I use DSLR HDR-video or CCD live stacking, sometimes video cameras.)

(From: Electronically Assisted Astronomy with Atik Infinity by Fallenangel, adapted)

 

My Own Attempt at a Definition

Electronically Assisted Astronomy (EAA) is the real-time or near real-time observation of sky objects with telescopes using electronic devices (cameras) in lieu of an eyepiece.

This term is newer than the more widespread concept of video astronomy, which is often regarded as non-congruent with the former. Originally, the term "video astronomy" refers to the technique of using a (possibly modified) video camera instead of the eyepiece, the signal of which is transmitted directly to a TV or a video monitor. It uses purely analog video technology and does not need a computer. The video images are displayed, depending on the exposure time, in real time or nearly real-time, one after the other, on the monitor and viewed on-site or transmitted to other locations. They can be recorded on a video recorder and thus, stored and later transferred to a computer for post-processing.

With the advent of digital cameras connected to computers via USB, video astronomy was extended to include a digital variant, which, however, requires a computer and monitor for display and storage. The images stored on the computer (typically not in video format) can be further processed on it, either later or immediately. Whether the digital variant can still be regarded as "video astronomy," is open to discussion. This is probably why the term "Electronically Assisted Astronomy" (EAA) was created.

EAA / Video Astronomy in its "instant imaging"* variant uses image stacking to step-by-step reduce noise and accumulate light while the sky objects are being observed. It shares the use of image stacking with "real" astrophotography, but it usually does not use dark images to correct hot pixels etc., or removes "bad" images (this is not always the case, though...). In addition, the results appear more or less "immediately" and thus, this technique aims at a direct observational experience, whereas in astrophotography the results are produced and viewed only after the photos were taken (which usually takes hours).

Because EAA / video astronomy highlights the observational aspect, it is also called "electronically assisted observation" (EAO).

Advantages

Disadvantages

Remarks

 

Experiences - Collection

In the following, I present some experience reports on video astronomy, which I found on the Internet. These are general reports and not reports of special equipment, as can be found in large numbers on the Internet.

Rod Mollise: Observing with Astro Video Cameras

Below are some citations taken from Rod Mollise's article Observing with Astro Video Cameras that he wrote for Sky & Telescope! Please note that he discusses the original concept of video astronomy without using a computer for image stacking.

(From: www.skyandtelescope.com/astronomy-resources/observing-with-astrovideo-cameras/)

Brian Ventrudo: The Emerging Art of Video Astronomy

Telescopes and Mounts for Video Astronomy

And of course you need a telescope. Which telescope works best with the current crop of astronomical video cameras?

To keep a long story short, for most commonly-observed DSOs, a telescope with a focal length of about 400 mm to 1000 mm works very well with the small sensors in these cameras. If you have a scope with a longer focal length, such as an 8" f/10 Schmidt-Cassegrain, you can acquire a small lens called a focal reducer which mounts between the focuser and the camera. The lens effectively reduces the focal length of the telescope by a factor of 2x or 3x. This also reduces the f-number of the telescope by the same amount which results in brighter images of extended objects and faster imaging time.

You also need to make sure your telescope will focus an image with the camera. This is not usually a problem with Mak-Cass and Schmidt-Cass telescopes. Refractors usually have no problem focusing also, though sometimes a small and inexpensive extension tube is required to position the camera a little further away. Newtonians can be a problem. Without custom modification, many Newtonians do not have enough travel in the focuser to enable any type of video camera to come to a focus.

For newcomers to video astronomy, perhaps the best telescope is a small ED refractor with a focal ratio of f/6 to f/7 and an aperture of 80 mm to 90 mm. With an astro videocam, these small scopes will deliver excellent images of celestial objects with medium to large apparent size. Depending on your setup, you will get fields of view with a small refractor of about 0.3° to 0.8°. This allows you to frame large and colorful emission nebulae like M 42, M 8, and M 20, many open and globular star clusters, larger galaxies like the M 31, M 81 and M 82, NGC 4565 and so on, larger planetary nebulae like M 27, and of course the Moon. You will see all these objects and hundreds more with much more detail than you will ever see in an eyepiece.

Images of smaller planetary nebulae and more distant galaxies are a little too small with such short focal lengths. That's when you want a larger telescope with longer focal lengths, though this will lead to very small fields-of-view which makes it trickier to find and track objects. In a perfect world, for both video astronomy and visual observing, you would have an 80 mm ED refractor and an 8" to 10" SCT and one or two focal reducers to keep the focal ratio low.

You will also need a motorized mount to track the sky when taking images of deep sky objects with a videocam. Even for exposures of a few seconds, the Earth's rotation will smear the image if the telescope mount is not tracking the stars.

But you don’t necessarily need an equatorial mount. You can track objects for up to 30 seconds with a motorized altazimuth mount with good results. In some cases, you can get away with tracking for 60 seconds. At that point, you notice the stars begin to elongate because of "field rotation," the slight apparent rotation of the stars as they move across the sky. An equatorial tracks this naturally. An Alt-AZ does not. But you can image a great many objects with a 30-60 second exposure on an astro videocam, especially if you have dark sky and do not require a light pollution filter to reduce the effects of a brightened sky background. Many experienced video astronomers use telescopes of 3" to 16" aperture only with motorized Alt-Azimuth mounts and they get very good results.

If you want to go after fainter objects, or if you need to use a light-pollution filter, you will often need longer exposures. In such cases, a solid equatorial mount with a motor drive will give you far sharper images. Also… with Alt-AZ or equatorial mounts, "Go-to" control is a big advantage to help you find objects with the narrow field of view of most videocams.

(From: The Emerging Art of Video Astronomy, Part 2 by Brian Ventrudo, adapted)

First Experiences of My Own

See page Atik Infinity Colour Camera - Experiences.

 

Some Collected Questions and Answers...

Here are some questions that I found in connection with video astronomy. Again, they are general in nature and do not deal with special equipment.

What kind of telescope do I need for video astronomy?
You need a telescope that fulfills three requirements: it needs wide-field optics (relatively short focal length), it must be able to reach focus with a camera, and it must have a motor drive - preferably one with GoTo pointing.

What is the optimal focal length of a telescope when used for video astronomy?
A telescope with a focal length of about 400 mm to 1000 mm (500-1000 mm) works very well with the small sensors in video or other cameras.

What can I do when the focal length of my telescope (SCT, ...) is too long?
Use a focal reducer (2 x or 3 x). This also reduces the f-number of the telescope by the same amount which results in brighter images of extended objects and faster exposure time.

What can I do when the camera does not come into focus because the focus point is too far inwards (Newton)
Use a Barlow lens (1.5 x, 2 x, or 3 x). This also increases the f-number of the telescope by the same amount which results in fainter images of extended objects and longer exposure time.

Can I use an Alt-AZ mount for video astronomy
You can track objects for up to 30 seconds with a motorized altazimuth mount with good results. In some cases, you can get away with tracking for 60 seconds.

Motor Drive: Can I start out in video astronomy with a simple Dobsonian telescope that doesn't have a drive to track the stars?
Unfortunately, the answer is no. The tiny sensor chips of astro video cameras make tracking objects (even planets) by hand an exercise in frustration.

Is a GoTo control useful for video astronomy?
With Alt-AZ or equatorial mounts, a GoTo control is a big advantage because it helps you find objects with the narrow field of view of most videocams.

Video Astronomy can be done with fairly small telescopes. Can this be expressed in figures?
Astronomic video cameras triple the aperture of a small telescope even under heavily light-polluted skies.

 

Preliminary Conclusions

With this page, I first of all intended to clarify what EAA and video astronomy mean for myself and for others. This was hopefully more or less successful.

I can barely contribute my own experiences at the moment. Therefore, I have collected some experiences from others that I found on the Internet.

After all, everyone has to decide for him- or herself whether this new direction is for him or her. In my opinion, there is no "good" or "bad", no "right" or "wrong" in this regard. I can fully understand that die-hard visual observers, who may even create drawings from their observations, pick on this direction, especially when people are "watching" from the couch using their laptop or smartphone, and drink beer and munch potato chips- and the telescope stands forlorn outside on the cold terrace. Likewise, I can understand when "real" astrophotographers pick on direction, because they have to invest a lot more time and effort in their results and have to wait longer until they see any results. On the other hand, their results are so much better that they can, and may, compassionately look down on this direction.

So, for whom is the new direction? I mentioned already the "couch astronomers." Then there are the impatient ones, those who do not want to spend a lot of time with star gazing, and the "ignorant" ones who hardly know or do not know the stars and the constellations in the sky, but still want to see "something". Then there are those who are not so agile and are reluctant to crawl under the telescope in order to be able to look through the viewfinder. Moreover there are people who have problems with their backs, and people whose eyesight has become poor, but also disabled people who are physically unable to get to and look through an eyepiece. In other words, there are a lot of people to whom this new direction can bring astronomy closer, or who are enabled to continue their hobby using this approach. And then I forgot myself, who often "sees nothing" when observing visually because of light pollution at home or for other reasons, but who can find, see, and even record the same objects with this method and thus, is significantly less frustrated using it.

 

Links

Practice, Experiences

Dedicated Sites

Live Broadcasting Websites

Discussion Forums/Boards

 

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made by walodesign on a mac!
18.01.2018