Easy Astro Photography
This web page describes a method you can use to take star object photos even if you don't have the gear to do that, using the Harvard-Smithsonian Astrophysics Lab MicroObservatory. You can learn more about the MicroObservatory at About MicroObservatory.
If you've been involved with amateur astronomy for awhile, you've probably gotten some itch to take photographs through your telescope. Some of you may have even tried, and found the adventure to be a bit daunting, or at least tedious. Even snatching a few moon images with a cell phone held to the eyepiece of your telescope is a challenge. A few of you have probably invested in the photography aspect of the hobby and collected some amazing photographs.
In some ways, the digital photography revolution has made some types of astrophotography easier, but it is a meticulous endeavor even so. I've only owned relatively inexpensive or homemade telescopes for my 60 years of observing, but I've managed to collect a few nice shots when I put in the effort. Even so I've managed some decent lunar and planetary photos, and even a small number of star object photos. But with my modest equipment I've not often been up to the effort it takes to obtain astronomy photos.
The Challenges of Star Photography
Star photography is a bit tougher than solar system (moon, planets) photography, or at least it takes some more equipment. With star photography, you need to take time exposures, at least of several seconds up to a few minutes.
In the old film camera days, this in and of itself was pretty easy. Any old 35mm camera could take time exposures, as long of exposures as you wanted. The problem for star photography was (and is) to keep the camera pointed precisely at the same stars during the exposure. To get a digital camera that takes times exposures over 30 seconds, you must make a serious investment.
To avoid star trails caused by earth's rotation, you need a motorized mount. And even if you have one, just putting a camera looking through the telescope and locking the shutter open doesn't cut it. For anything over a few seconds exposure, you need to either view through a guide telescope so you can make adjustments on the fly, or invest in an auto-guider that will feed back to control the mount on the fly. A lot of amateur telescopes don't have a mount that has that feedback capability, leaving you with the guide scope approach.
Adding a guide scope increases the weight of your apparatus, upping the strength requirement of your telescope mount. It also means making the entire package less portable, if that is of importance.
The Simplest Star Photography -- Piggyback
If you can be satisfied with low magnification, wide field images of the stars, you can just mount a camera piggyback on your telescope as shown above, letting the camera use its own lens (or a telephoto lens) as the telescope mount moves the mount to compensate for earth rate. This lets you use the main telescope as the guide telescope. This doesn't up the requirement of your motor driven mount very much.
Again, an old 35mm camera is still a pretty good option for this, as most any model can have the shutter locked open for as long as you need. You'll still need a significant investment if you want to do this with a digital camera, in that inexpensive ones don't do long time exposures.
Below is an example of piggyback
photography.
It's an image of Hale Bopp comet as it appeared some years ago, taken with a
very modest telescope and a clock driven mount, and a camera with a 135mm
telephoto lens taking a ride alongside the telescope.
There are a lot of star fields, some large nebula, and sections of the Milky Way that can be photographed using piggyback photography. There are some interesting events, like times the moon passes near a star field or plant, or when a planet is in a star field. You just need some kind of Piggyback Camera mount, like this Piggyback Camera Mount, to hold your camera.
Star Object Photography Through the Telescope
But the real prize is time exposure of star objects directly through your (or a) telescope. Telescopes provide the light gathering power and small field of view that allow images like the Orion Nebula shown below:
That's the kind of image I've been wanting to achieve for years, but never felt I could invest in the equipment that would make such photographs possible. Now that I'm older (much older), I'm not into the tedium that such an effort might take. Outdoor tedium anyway. But I am into computer tedium on taking raw data and processing it into a photo.
Enter the Remote Observatory
So if you share the star photography desire, and also have the concerns of cost and or time expense, you can try what I did. I searched for a remote-controlled telescope that I might get access to so that I could get images with that equipment, then use my own software to process the images. There are now a few of those observatories around that allow most anyone to use them. Some are freely available, and some work on a subscription basis, usually some tens of dollars per month.
The free observatories are usually housed with smaller instruments, and the subscription ones with larger instruments. I decided to try out a facility created by the Harvard-Smithsonian Center for Astrophysics called the MicroObservatory. The facility is primarily intended as an aid for teaching astronomy with some hands on experience, so it is geared for teachers and students. Even so, some use of the facility is open to the general public.
The MicroObservatory consists of about 5 remotely controlled 6 inch Maksutov-Newtonian reflectors. They are pretty portable units, so they get moved around some. At the time of the writing of this web page, some of the instruments were at the Harvard College Observatory, some at the Whipple Observatory in Amado, AZ, and at least one in the Coquimbo region of Chile.
At the MicroObservatory Web page, you can select items you'd like to obtain photos of from a modest but common collection of possible targets. You specify the desired Field of View (sometimes only one is appropriate and available), the exposure time, and any filters you'd like used. You then supply an email address and answer a few questions on the request form. Within the next day or two, depending upon weather conditions at the telescope sites, you'll get an email with links to your images.
What Do You Get
The images you are given links to are raw images. Raw? Yes, the images are certainly not immediately impressive, and will require some work to produce what you want, kind of like the work involved in developing film.
If you go for nebulae, then you likely want color images, and for that you'll receive 3 images each taken through a different color filer (red, green, and blue). From those raw color filtered images, you must construct a full color image.
You are unimpressed I bet. Now you get a feel for the processing that must be done to get the image of Orion shown earlier in this page. You can see some bleeding spikes, and when processed likely some odd tails on some of the bright stars. These are results of some saturated pixels bleeding over, and some processing issues on site. You have to deal with all of that to get your image.
So while you're not using your own telescope, you aren't exactly getting a finished product you can jam into your web site or blog, either. But with some processing, you can get images of decent quality for the size of telescope (6 inch).
There is an image processing lab on the MicroObservatory site, so you can process your images there if you like (there are tutorials), or you can download the images and work on them on your own computer. My choice is to download the images and create my own software for processing, as that's a main interest of mine.
The image processing app at the MicroObservatory web page is a clever and well written Java application. For my home-grown processing, I work primarily with Perl and the PDL perl extension. Perl with the PDL extension is loaded with image processing capabilities, designed in fact by astronomers some years ago. Some of the images I processed with software created with the Euler Math Toolbox
As a footnote, it's worth mentioning that if you are interested in this approach, there's an additional benefit, the details of which change time to time. That is, the MicroObervatory telescopes, being small at 6 inch aperture, are portable and get moved around some. And as mentioned, at the creation time of this web page in 2020, at least one instrument was located in the Coquimbo region of Chile, giving access to Southern Hemisphere targets.
Processing MicroObservatory Images
As mentioned earlier, there is a utility on the MicroObservatory site for processing images. It gives a number of controls, including merging red, green, and blue component images to create a color image. In general the process is:
hotpixels (anomalous pixels much hotter than surround pixels)
Some MicroObservatory Image Examples
On this web page are displayed a number of images I obtained using the MicroObservatory instruments. They consist of a collection of open clusters, globular clusters, nebula, and galaxies. One moon picture is included, though the system is most useful for star object pictures. In each case I downloaded the raw images when they were available, and worked to produce the final products you see here. Some of the images were processed with programs written in Perl, using the PDL math/graphics extension. Others were processed with the Linux version of Euler Math Toolbox.
Photos Taken With MicroObservatory Instruments
Processed With Perl PDL or Euler Math Toolbox
Open Images in New Tab for Enlarged View
Moon, 6 inch Mak-Newt MicroObservatory Telescope at Amado, AZ, 0.1 sec exposure.
2021 Lunar Eclipse via MicroObservatory. The MicroObservatory only provides b/w moon images, so this had proper lunar eclipse color added.
Orion Nebula, 6 inch Mak-Newt MicroObservatory Telescope at Amado, AZ, 60 sec exposure, stack of 5 images.
Andromeda Galaxy, 6 inch Mak-Newt MicroObservatory Telescope at Amado, AZ, 60 sec exposure, stack of 17 images
Crab Nebula, 6 inch Mak-Newt MicroObservatory Telescope at Amado, AZ, 60 sec exposure
M101 galaxy, 6 inch Mak-Newt MicroObservatory Telescope at Amado, AZ, 60 sec exposure
M15 globular cluster, 6 inch Mak-Newt MicroObservatory Telescope at Amado, AZ, average of 6 60 sec exposures
Pleiades
Pleiades cluster, 6 inch Mak-Newt MicroObservatory Telescope at Amado, AZ, average of 9 60 sec exposures taken through finder
M33 galaxy, 6 inch Mak-Newt MicroObservatory Telescope at Amado, AZ, average of 12 60 sec exposures
M82 galaxy, 6 inch Mak-Newt MicroObservatory Telescope at Amado, AZ, 60 sec exposure
Dumbbell nebula, 6 inch Mak-Newt MicroObservatory Telescope at Cambridge, MA, 60 sec exposure
M13 globular cluster, 6 inch Mak-Newt MicroObservatory Telescope at Cambridge, MA, average of 8 60 sec exposures
M57 planetary nebula, 6 inch Mak-Newt MicroObservatory Telescope at Amado, AZ, 60 sec exposure
Helix Nebula, 6 inch Mak-Newt MicroObservatory Telescope at Amado, AZ, 60 sec exposure. This needed more exposure, but public use of the equipment didn't offer longer exposures.
Pinwheel galaxy, 6 inch Mak-Newt MicroObservatory Telescope at Amado, AZ, 60 sec exposure
Whirlpool galaxy, 6 inch Mak-Newt MicroObservatory Telescope at Amado, AZ, 60 sec exposure
Centaurus A galaxy, 6 inch Mak-Newt MicroObservatory Telescope at Amado, AZ, 60 sec exposure
NGC891 galaxy, 6 inch Mak-Newt MicroObservatory Telescope at Amado, AZ, 60 sec exposure
Images From Southern Hemisphere Instruments
Beehive cluster, 6 inch Mak-Newt MicroObservatory Telescope at Coquimbo, Chile, 60 sec exposure
Omega Centauri globular cluster, 6 inch Mak-Newt MicroObservatory Telescope at Coquimbo, Chile, 60 sec exposure
Carina Nebula, 6 inch Mak-Newt MicroObservatory Telescope at Coquimbo, Chile,
Tarantula Nebula, 6 inch Mak-Newt MicroObservatory Telescope at Coquimbo, Chile, 60 sec exposure
47 Tucanae globular cluster, 6 inch Mak-Newt MicroObservatory Telescope at Coquimbo, Chile, 60 sec exposure
Rosette Nebula, 6 inch Mak-Newt MicroObservatory Telescope at Coquimbo, Chile, 60 sec exposure
Large Magellanic Cloud, 6 inch Mak-Newt MicroObservatory Telescope at Coquimbo, Chile, 60 sec exposure
Small Magellanic Cloud, 6 inch Mak-Newt MicroObservatory Telescope at Coquimbo, Chile, 60 sec exposure
Lagoon Nebula, 6 inch Mak-Newt MicroObservatory Telescope at Coquimbo, Chile, 60 sec exposure
Trifid Nebula, 6 inch Mak-Newt MicroObservatory Telescope at Coquimbo, Chile, 60 sec exposure
Eagle Nebula, 6 inch Mak-Newt MicroObservatory Telescope at Coquimbo, Chile, 60 sec exposure
Homunculus Nebula*, 6 inch Mak-Newt MicroObservatory Telescope at Coquimbo, Chile, 60 sec exposure
M21 Open cluster, 6 inch Mak-Newt MicroObservatory Telescope at Coquimbo, Chili, 60 sec exposure
NGC2477 open cluster , 6 inch Mak-Newt MicroObservatory Telescope at Coquimbo, Chile, average of 7 60 sec exposures
NGC253 galaxy* , 6 inch Mak-Newt MicroObservatory Telescope at Coquimbo, Chile, 60 sec exposure
Summary
The archive indicated images were those I either didn't ask for on the MicroObservatory request form, or the images I requested didn't turn out well. So in those instances I pulled a raw image from the MicroObservatory archive and processed that with my software.
So, what do you think? I've read of some dedicated amateurs who think that using such a facility is cheating. I guess I look at it as sharing a telescope. The instruments of the MicroObservatory are about the same size and optical capabilities as the instruments that many amateur astronomers have (6 inch), but are specialized in having more robust and higher precision mounts, plus a built in CCD camera.
I could alternately invest several hundred dollars into an astro-camera with auto-guider and equip my Celestron Nexstar 5SE for the task. But with an auto-guider, I'd have about as much photographic skill involved in the image taking part as I have using the MicroObservatory. In either case, I'd be using my computer and programming skills to reduce the images, as I am with the MicroObservatory images.
It depends on which end of the photographic exercise you get the most fun out of, the instrument handling part or the computer image processing part (or both). I enjoy the computer processing part the most, so using the MicroObservatory to gather images that my equipment isn't set up to handling seems a good compromise.
So it's clearly up to you. The MicroObservatory uses amateur sized instruments, and provides you only the raw data (images). For me, it allows me to put my funds into great portable telescopes for observing, and not have to move to much more expensive and less portable telescopes to do the photography, which for me is just a hobby anyway.
While there is still tedium involved in processing the images to their fullest potential, there is no tedium in getting the raw image. It also lets me stay engaged in astronomy during the winter months where my old bones limit my willingness to venture out on cold nights. For solar system photography, I can get great results with my ETX 90 and NexStar 5SE, which I intend to still use occasionally for that purpose.
If any of this sounds interesting to you, you may want to check out the Harvard-Smithsonian MicroObservatory for yourself. It costs you nothing. How can you lose?
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