Some basics of astrophotography and a few links.

Some comments about astrophotography and a few links are in today's post.

At almost every outing someone will ask us about astrophotography.  They will mention they'd like to get a telescope and camera to "do astrophotography".  Astronomers both Amateurs and professionals really enjoy looking at the great photos people take of deep sky objects, the moon and even wide fields shots of the sky which show star fields, northern lights, meteors or star trails.  It's fun to get a nice photo and show it off to others.  It's difficult to compete with the photos we see in many textbooks, especially the Hubble photos or those from deep space probes which fly by the planets.  But we can get some exceptionally nice photos with "modest setups".  The key is knowing what is modest and how much effort it takes to get really nice results.  A modest setup could be something as simple as a DSLR with a barn door tracker or a camera tripod.  Or it could be a mount that costs $600 to $10,000 dollars, a telescope costing $300 to $10,000 and a camera that costs $100 to $10,000 or more, plus filters for some applications.   It all depends on your budget and what you can afford to spend.

You can take basic photos fairly easily but to get serious it will cost a lot of money. Typically five to ten times more than visual observing, because we have to have very precise mounts, cameras and spend a lot of time learning and processing photos.   To visually observe we have two basic paths.  You can get a light bucket or "Dobsonian" telescope which is a "Newtonian reflector" on a basic base.  Orion and other companies sell these and this style offers the most bang for the buck as far as looking at faint objects for less money, visually.  Or you can get some small telescope a refractor or perhaps a small SCT that has a tripod and mount that tracks.  It may be something like a $600 Celestron 4SE that has a 4 inch mirror.  The Dobsonian telescope, a basic reflector from Orion might cost you $400 to $500 for a ten inch mirror. It will show a lot more and fainter objects, but you have to manually find them.  The Celestron 4SE will not have the light gathering power and is a different kind of telescope.  It's mount will  track and find objects.  If you "tilt" it in EQ configuration with the built in wedge mode, in theory you can take some pretty decent astronomy photos with it, by adding a camera.  But many of these small mounts and telescopes have a limited load capability and the camera will add load to the telescope motors.  The typical Nexstar 4SE mount for example will barely drive the telescope, much less the telescope with a 35mm digital SLR attached.  It's motors are basically rated for the telescope for visual moving about and it will strain and not always give great results with a heavier load.  Some other lower cost telescopes offer an EQ styled mount but there are manual setting circles.  These often are to cheap to be reliable and are meant for casual tracking while viewing on some popular mounts that are manual like a Vixen mount the little manual knobs don't always work very well and don't offer fine enough tracking movements for astrophotography.  You can create a "barn door tracker" for manual tracking, but this is for wide field astronomy views with a digital SLR mounted on the "barn door" mechanism.

I don't want to be a person to discourage anyone in this pursuit, but it's not as easy as many would think. There are many levels of astrophotography. Probably at least three or four basic levels, from beginners to advanced. They can cost a lot of money, but it costs less to do the more basic stuff.

I'm going to briefly mention the different ways one can take astronomy photos of the sky. I'll start with the more expensive ways but wander around a bit writing a bit about different ways of taking astrophotographs.

You will need a telescope or lens on a camera and some kind of mount. The better photos may take fainter pictures, including deep sky dust clouds and colorful nebula glow or white faint glowing of billions of stars in the arms of a galaxy.  These usually are taken with equatorial mounts that are carefully aligned with the polar axis of the earth and at least a DSLR camera, but often a dedicated Astrophotography camera.   An entry level SBIG camera at times has been as low as $1800 for a monochrome camera, and there are some entry level dedicated cameras for astrophotography that are in the $1000 to $2000 range.  

These equatorial (or EQ) mounts often have expensive mounts and precise drive motors. There are also wedge adjustments for fork mounts, but these are often as difficult or more difficult to setup than an EQ mount. Wedges on forks are a bit of a compromise but take up less space.  They often weigh quite a bit when you include the wedge.  Many Meade models of telescopes that are on a "fork mount" have a telescope permanently attached to the "fork" so these cannot be disassembled to carry out and setup with a lighter load.  A compromise on the wedge fork setup is a single arm like the Celestron Nexstar series of telescopes with only one fork arm on one side.  These telescopes offer the ability to slide the telescope into the single fork, making it lighter to setup.   These "nexstar" one sided forks offer a bit less heft for setup and allow one person the ability to setup a bigger telescope, but they may be less rigid and some complain that they are not as easy to use and may not be as beefy for astrophotography.  The Nexstar line is the "cheaper mount" line and offers more bang for the buck.  This means it is better for optical observing.  But to do astrophotography, you would be better off with an EQ mount.  A low end EQ mount would be something like a Celestron CG5 which costs about $650.

Liability of Fork mount design compared to EQ.
A fork mount design has two arms one in each side if the telescope. The mount will cause vibrations in it's design because it's a fork, like a tuning fork vibrates it will amplify vibrations and can be less stable than a German equatorial mount or EQ mount. Big observatory telescopes are huge and often mounted on forks, but they have millions of dollars to design systems to compensate for fork vibrations. A fork mount is more portable and has no counter weight to bump or hit, so fork mounts are popular at star parties and for visual observing. With astrophotography, amateurs often have an EQ mount. Sometimes a small mount that they bought separately from an American maker, like Losmandy. The Losmandy GM-8 mount is an example of a light weight small EQ mount that some astrophotographers use. It's light weight and has nice capability, but it is a light mount for small refractors or small telescopes. We often buy a mount that is rated for twice the weight of the load we'd use for astrophotography. If your mount is rated for 15 lbs, you might only want a 7 lb rig on it for astrophotography. There are also some cheap mounts that astronomers may use that are portable and used with dslr cameras with zoom lenses. Vixen makes one of these for about $400, but it's suitable for mostly wide field work and a very basic setup. More like a tripod, small mount and camera bag setup you'd carry while on vacation to setup for wide angle photos in a remote location.

If you have a larger mount say a Losmandy Titan mount (which is what we have at HJRO), it will cost a lot of money. The Losmandy Titan costs $7000 and has a 110lb rating for that mount. Good for carrying a hundred pounds of telescopes for visual.  We have three telescopes mounted on our Losmandy Titan mount at HJRO.  For astrophotography, we'd want that to ideally have a telescope package of about 50 lbs, half the rating of the mount.  With less to move we should have a more steady track and image. Tracking setups may include a separate small telescope and tracking camera to make adjustments, guiding adjustments to the mount as the photo is being taken.  In some cases you can get a fairly nice telescope that is nice an economical, but it's heavier and requires a more expensive mount.  Also if you're imaging outside and have a large telescope that has a long tube, like a long tube newtonian, you may have to overcome wind currents which are blowing on the tube.  Even light wind currents will put a load on a mount.  For this reason many astrophotographers will not want to image when it's windy outside.  An observatory or wind break may be necessary.  Of course a shorter tube or smaller telescope might see less effects of winds.  When it's gusting out you'll find that the air if humid may offer poorer seeing conditions as well.  Ice crystals and water droplets and particles in the air may make the stars jump and move around, this due to refraction of the star images or light that is traveling through our atmosphere.  The more you notice stars twinkling the worse the air disturbance.  Some astrophotographers will not image if they can see a star twinkle with their naked eyes when checking out the seeing conditions.

- Advanced astrophotography cameras
Some cameras, specifically, the SBIG line of cameras have a ccd system that has dual pickups picking up the image off the same CCD chip.  One image is the image that goes to your image capture and a second image from the same CCD array is used to "track" the image.  SBIG has a patent on this using one chip for exposures and tracking. SBIG cameras that have this tracking feature cost about $4500 or more.  SBIG has cameras that are less expensive but they don't have this dual tracking feature.  There is an advantage to dual tracking over using a separate telescope.  If you use a separate telescope and camera to "track with" the flexing of the telescope tube and differences that are minor may show up in the tracking and affect it.  This of course is information from higher end applications those seeking to get the best photos possible.  Many astronomers use a second camera (often a cheaper monochrome camera) as a tracking camera and that feeds a computer or some mounts with "tracking changes" to keep the image in the same position during the exposure of the photograph.   The computer mount can also be "trained" for PEC correction as well, which is a way to train a mount to get rid of problems in "tracking" that come from imperfect gears which are not cut to precision.  There is a lot of details and added things that you can learn and do to get better and better photographs.  Having a dark sky site also helps a lot, in an urban setting with a lot of sky glow your pictures and capabilities will be challenged.

For those looking to spend a lot of money on a dedicated Astronomy camera, there are other choices and questions you may want to ask, which may depend on the equipment path your pursue.  Some cameras are extremely small and these work better if you're using a special configuration called "hyperstar" or "Faststar".  This is a special configuration available for some astrophotography and is rarely used.  A big astrophotography camera that may cost less than a small one, may have a disadvantage when if you are trying to do "hyperstar" imaging.   (More on that later near the end of this blog.)

The advanced astrophotography cameras are designed for astrophotography from companies like SBIG, Orion, Celestron and Meade or one of many other camera manufacturers. These ccd cameras have cooling fins and fans on them and their size weight and price can vary. They cost anywhere from $1000 to $10,000 or more dollars. Many astronomers have astrophotography cameras that cost between $3000 and $5000 dollars, and they may have a second camera for "guiding". There are some cameras that cost much less of course. The cameras need to be securely attached to the telescope. Most astronomy cameras are attached by sliding the camera tube into the eyepiece holder.  The telescope will be focused carefully and the focus may change over the course of the night and refocusing may be performed between different photographs.  The astrophotographer may even have computer controlled focusers to change the focus by as little as a millionth of an inch to get precise focus.  Some pieces of software will automatically refocus the telescope with a command from the computer.  These extra features will cost even more.  Some backyard observatories have remote focusing, remote control and even have sensors to detect rain and can be operated and open and close remotely over the internet.

Regarding focus:  The telescope tube will expand as the telescope heats up.  It may shrink slightly when the temperatures drop.  Different telescopes may expand or shrink differently depending on their construction.  A standard C14 with a standard metal tube will expand and shrink more than a C14 with a carbon fiber tube.  Some astronomers get carbon fiber tubes to reduce the expansion and contraction that happens during changing weather.   Mirrors on large telescopes may have to be equalized with the temperature of the surroundings.  The larger the piece of glass, the longer it may take for the mirror to adjust to the temperature.  Some telescopes have mirror blanks made up of exotic material that expands and contracts less.  Some companies offer these mirrors, made of zerodor or quartz as options for astronomers who don't want to wait as long for a mirror to be thermally equalized with the environment.  Carbon fiber tubes or trusses, exotic mirrors often are used by the more discerning astronomer who has a lot more money to spend.  They can help a little bit overcome some of the changing weather conditions that affect the optical quality of the image we are trying to capture.

Most astronomers don't have exotic instruments however.  Most have mirrors made of normal pyrex glass or it's equivalent.  With these mirrors or lenses they may still get great results.

DIFFERENT WAYS TO TAKE PHOTOS.
There are different ways to take photos at different zoom levels and exposure levels.

Here is a list of the most common ways astronomers take astronomy photos.
1. POINT AND SHOOT AFOCAL - through the eyepiece photography.
2. DSLR mounted to a telescope with a T-Mount or piggybacked on a telescope.
3. DSLR mounted on a camera tripod with no tracking.
4. DSLR mounted on a small tripod with a tracking motor or a barn door tracker.
5. Webcam mounted to a telescope for planetary or lunar.
6. Astrophotography camera mounted to a telescope.
7. Video camera designed for astronomy mounted to a telescope.

I'll try to cover some of these briefly

Point and shoot through the lens.
One can use a simple camera, even your camera phone and take a quick handheld photo of the moon through almost any telescope. This will give you a quick photo of the moon. It's easy to get decent photos of the moon, and relatively easy to get nice shots of some planets with a little bit of investment and a telescope.  I have found the best results with point and shoot cameras for the moon using a low power eyepiece with a big piece of glass.  You can zoom into that eyepiece to reframe the moon.  A low powered eyepiece will often work best.  We have had some pretty amazing photos through our C14 at HJRO with a big low powered eyepiece.  For planets you will probably only get good results with a point and shoot with a very high powered telescope, meaning a large telescope and a high powered eyepiece.  This may require a tracking mount.  At HJRO we have a large telescope and I've taken some pretty good photos with my iphone through a high powered eyepiece in the eyepiece and with a barlow lens as well doubling the power of the eyepiece. Some of these photos were at powers as high as 888 power, which is much to much power for visual observing at our location.  The image looks fuzzy in the eyepiece because of the high power, but the camera is capturing color detail and sometimes we can get a decent results which are pretty amazing for a camera phone.  Point and shoot cameras like the iphone don't have exposure control, so you may have to control the brightness of the object using a dual polorizer filter which is normally used for the moon, but you may need that for Saturn or Jupiter.  Jupiter and Saturn may be large enough targets for cellphone point and shoot photography, through a large telescope like the C14.  But smaller planets like Mars, will show no detail and will likely be overexposed.   You'd want to use a webcam, or DSLR or dedicated camera for Mars or other planets.  (These other planets often don't offer detail.  Mars will often not show much detail, and little detail except when it's in opposition above the earth in the night sky near midnight.)  With these other planets we often see not much more than a colored disk.

DSLR cameras (unmodified and modified for IR.)
One can also use DSLR cameras. These of course cost $500 to $1000 on the low end.   DSLR cameras come in "full frame models" that are like 35mm cameras with a bigger sensor size.  The larger "full frame sensor" DSLR cameras often cost over $3500.  DSLR cameras are also mostly "unmodified" and won't capture Infrared light.  Ideally a DSLR could capture IR light and most cannot.  Most can be modified, but that modification will void the manufacturer warrantee, so that is a risk.  The modification is the removal of the IR filter and it's often replaced with a different kind of filter.  Gary Honus is a person who will modify a DSLR for a price and offers instructions on how to modify one if you want to risk a modification and camera for your astronomy pursuits.  (See the last link of this post for more information.  Canon currently makes a DSLR camera that will capture IR information as well but it's not a full frame camera, it has a 3/4 frame size sensor.  Many moderate priced DSLR cameras have 3/4 frame sensors which are a little smaller.  They will crop the image a bit from some telescopes making the image a little smaller and not as wide a field as a full frame sensor could capture.  The act of cropping a frame by having a smaller sensor will make a photo appear closer because it's like a digital zoom.  In extreme examples of cropping from "webcams" or from Video cameras modified for astronomy, the cropping of the image may make the camera operate like a high powered eyepiece.  This can be good for planetary viewing giving you a closer view, but bad for wide field captures.

A DSLR camera can take some pretty good astronomy photos. You can start taking wide field camera exposures of the night sky with a dslr. It may resemble a night landscape photo and show some of the ground if you use a wide angle lens and are aiming close to the horizon. Some point and shoot digital cameras can take these photos as well. I used a camera like a nikon coolpix, to take wide field shots of the sky at first. I found the manual setting and set the exposure to take a 30 second photograph at set the iso setting to the brightest setting 1600 iso I believe if I can recall the setting correctly. And I put the camera on a tripod and aimed the tripod up at the sky. 30 seconds later because the camera was focused on the stars, I had a photo of constellations and could make out the night sky.

I took more than one photo with that and practiced Stacking techniques with those photos. But a point and shoot cannot get very faint photos and many star details, the lens is often very small on these. A DSLR will have a better lens.

Astronomers often recommend Canon DSLR cameras, the EOS line. We recommend Canon because there is more control and astronomy software for Canon DSLR cameras geared toward astronomy.  You can use a Nikon or other brand DSLR, but the Canon DSLR camera may offer features or software may exist from third parties that make it more practical for astronomy.  If you don't own a Nikon or other brand DSLR and want to someday get into astrophotography, I'd suggest following the advice of others and buy a Canon DSLR.  With a DSLR you can take other photos as well and it has many uses including astronomy uses.  (A DSLR will have some limits compared to dedicated and more expensive astrophotography cameras.)

- LIVE VIEW on a CANON EOS is a big advantage.
Canon makes some DSLR cameras that offer LIVE view previews allowing you to focus the camera with a zoomed in digital live preview. This feature is very handy and let's one focus precisely on a bright object in the sky without a laptop computer attached to monitor your focus. If your looking for a Canon EOS for astrophotography, make sure it has the the live view feature.

Once again most DSLR cameras don't normally capture Infrared light. You can get more long exposure detail if you can capture infrared light, but many DSLR cameras have a blocking filter inside that blocks out this extra red light from normal photographs we would take. You will see more detail for example from a long exposure of the Orion Nebula with a camera that can capture the IR light.  The IR light is added as red light and makes the nebula appear more "pink" but shows more gas details.  Many like this extra detail, so IR photography is often used with serious astrophotography cameras.
We don't see infrared light with our eyes, but it's out there and adds detail to some objects in space.

It could be argued that IR light photographs are really artificial because our eyes don't see the light and we wouldn't see that light if we were out in space looking out of a window at a nebula.  But our eyes don't see color when it's faint at all, our color sensors in our eyes are much less sensitive to color than black and white.  So low light viewing often will show only white for faint objects.  The camera picks up color being 70% efficient.  It will convert 70% of the colored light to an image.  Our eyes are only 5% efficient, and in low light they will not fire and we will only see black and white images.  A long exposure makes the images more colorful and brings out more detail.  So cameras are really showing us more fainter detail and in a sense a kind of artificial reality.  We would not see the Orion nebula in all it's color detail if we were flying right next to it, because the color would be widely spread out.  Even if we were close to the Orion nebula in a space ship we would not see the color we can detect with a common astrophotography setup.  The bright glowing colors in space often represent plasmas that are glowing from radiation or scattered radiation.  If we were close to many of the pretty displays, the radiation would make those displays dangerous for our biological life as well.  The pretty parts of the universe are often dangerous places.

Canon makes a special EOS camera that is geared toward astronomy called the 40DA. It's model number ends with "A" for Astrophotography. That camera has no infrared filter, it actually has a filter but it doesn't block infrared sources in the range that would come from space, so you can get more "red" detail with a Canon 40DA camera than you'd get with my Canon EOS T1i or many standard Canon EOS cameras. The t1i I bought cost me about $800. A 40DA would cost us about $1400 in the USA.

There are cheaper DSLR cameras in the Canon line that work very well also, like the EOS t3i.

You need a telescope of course to get a closer shot unless you have a very powerful camera lens. To take a decent long exposure photo we need to have a way to move the camera and counteract the effects of the earths rotation.

BARN DOOR TRACKER
There are simple devices you can create like a Barn Door Tracker that one can construct. Google "barn door tracker" for more information.

Barn door trackers use a screw and nut and bolt and a few hinges and a couple of pieces of wood to track the sky. Barn door trackers use a manual crank that the operator turns, "once a second" to cause the barn door to slowly open and move the camera which is mounted on a pivot mount, to track the stars and counteract the earths rotation.  The hinge of the barn door tracker will be aligned with the axis of the earth.  As the barn door opens or closes depending on the orientation of your setup, it may counteract the rotation of the earth.  A home made, barn door tracker could be easily made for less than $50.  You might be able to take exposures of a few minutes with a barn door tracker.

ADVANCED METHODS - A brief description.
By the nature of the CCD chip, noise electrons will cause a stray light dot pattern that is a low noise to appear on the image sensor. Also some bad pixels may stay lit.  There are special processing methods that Astrophotographers use to negate these negative effects of "noise" and "bad pixels".  This is done by taking other kinds of exposures and more exposures of the object and often using dark frames, white frames and stacking processes.  I'll spare the reader the details of this for now in this blog post, it's a more advanced subject.  Stacking involves using multiple exposures and getting a better image.  That requires taking more photos, or taking a video clip of the object if it's a bright object.

A SIMPLE EXPOSURE WITHOUT TRACKING - The circular star pattern around the north star.
There is an easy way to take a long exposure photo and see star trails which go around the north star. This is setting up your camera on a tripod and aiming it at the north star. Set the camera for a long exposure. Many DSLR cameras have a remote that may be used to trigger a really long exposure, or you can take many long exposures and merge them to create a photo with star trails. Or create a movie from the stills.

A photo of more than ten or fifteen seconds will often display star trails if it's on a fixed tripod that is not tracking the changing sky rotation. The closer you zoom in or the more powerful your telescope the larger the star trails will be. The close you are shooting toward the celestial equator, the greater the stars will appear to move.

Also if you are using a telescope that "tracks" the sky but it's not oriented as an EQ mount, moving opposite of the earths axis but using two motors, you will get "field" rotation in long exposure photographs.  That is another problem with simple goto telescopes that have an Alt/Azumuth mount.  Those tracking setups are geared toward visual viewing, not long exposure photography.

- Webcams, lunar planetary cameras ($100 or less, plus a laptop.)
Another economical way to take photos of some objects is to use a webcam or webcam based astronomy camera. Celestron sells one for about $100. This will mount on a telescope where the eyepiece would go. It will take stills and images of the moon and planets. You may even get some bright objects but faint objects will be challenging and probably not show up.

Webcams can be modified and there used to be a few basic webcams that would work with "mog-adapters". These are not easy to locate anymore. Some take a web cam and quickly attach it to a 35mm film plastic tube with both ends of the film tube cut off. They will use electrical tape to attach the web cam to the film container and the film container becomes the eyepiece tube that fits in the eyepiece holder of the telescope.

A $100 Celestron webcam based camera is a little more expensive, but it requires less work.  Regarding laptops many low cost laptops available now ($350) are suitable for astrophotography and webcam use.  You can capture and process photos with a common PC laptop.  For the moon and planets, many use REGISTAX software which can be downloaded off the web for free.

With a webcam and a higher powered telescope and a laptop one can take movies of planets or the moon. We can take an AVI video of a planet or the moon and then take that recording and process the movie using this free program called Registax. Registax can automatically align and throw out bad frames that are out of focus.  It will allow a person to create a much better photo with the help of your PC computer.  Some of the best astronomy photos of planets by amateur astronomers were captured with AVI movies and use a stacking process.

There are expensive programs one may buy as well to process a photo, programs like Deep Sky Stacker, Images Plus, or Adobe Photoshop.  One can easily spend thousands of dollars on imaging software to manipulate the photos.  Many astronomers use Photoshop to do complex processing of the image.  Photoshop retails for about $600.  That's another expense to consider.  One can use a cheaper piece of software like Explorer Scientific's Image Labs instead of Photoshop, but you'll find many other astronomers talking about and showing Photoshop tricks for image processing that you can't easily copy and use.

Nebulosity for Macintosh and Explorer Scientifics Image Labs for PC are nice programs as well.

The Macintosh has a disadvantage in astrophotography, because of Registax running best against AVI files recorded on a PC platform. Registax can run on a Macintosh, but many of the Macintosh programs run and record QuickTime which compresses the images, losing fine detail. AVI files recorded on a PC for astronomy have no compression and take up a huge amount of space. That is necessary for better images.  If you were running a full version of Windows under you Macintosh perhaps using VMWare, you might be able to get the advantages of Registax for the PC on a Macintosh.

BACKYARD EOS
There is also a program that uses a DSLR like a webcam and records the screen image from Live View. It's called "Backyard EOS", for the PC. It is a great program for using a DSLR like a webcam to record AVI files on a PC. I've used it on my Toshiba laptop to record some nice movies of Jupiter and the moon which I could process. backyard EOS costs about $40, well worth it if you like planetary and lunar imaging and have a DSLR with live view.

- High end Webcams (Point Grey research for example)
There are also high end webcams, or cameras that act like a webcam but take high end photos. The one most popular for planetary imagers is a webcam which is made by Point Grey research called the Flea3. This is quite expensive.  I believe it's in the $1200 to $1400 range.

Advanced monochrome techniques using filter wheels - Filters and filter wheels (starting at $100 per filter and $1000 for the filter wheel housing.)
Many astrophotographers get cameras that are monochrome, that is they only take black and white (grayscale) images. The reason for this is a black and white ccd system can record 8 to 16 times fainter light. This means you can get the same image intensity 16 times faster by imaging in black and white. Using black and white cameras requires more images to get color images.  You have to expose more than one image or sets of images using colored filters for different exposures and join these to create a color photo.  For really faint detail or a quick survey of the sky, a monochrome camera is desirable. To get color images astronomers will use filters and filter wheels. The filter wheel and filters can easily add a couple thousand dollars to the price of your camera. So a monochrome camera that costs $3000 with a filter wheel could put your camera setup in the $5000 range.

Hydrogen Alpha telescopes gather only a certain frequency of red light and show off solar flares and filaments blasting off the sun.   If you are taking an image of the sun through a hydrogen alpha or HA  telescope, the colors of a HA image will not register on the color sensors of a color camera.  The missing pixels which appear in the image may create a moire pattern on you exposure.  To avoid those artifacts you're better off using a camera that records all the red light from a solar telescope and this means using a monochrome camera.  A monochrome camera is more desirable for solar astronomy.

OTHER USES OF FILTERS
Astronomers will use filters to get rid of sky glow, add detail or get color images. They might use a luminance filter, a Red, green and blue filter and take for photos through each or four sets of photos through each. During image processing, the astronomer will combine the different color exposures and get color photographs. They may process the different colors separately and do a wide variety of processing techniques. They may shoot with three, four or five different filters. And with astronomy the sky is the limit with your budget, you can get some filters for thousands of dollars per filter. There are some premium filter makers and also inexpensive filters offered by other companies.  Filters from Orion are on the low end of the price spectrum. Some German made filters can be purchased having extreme quality and durability. The bigger filters for 2 inch setups cost much more than a 1.25 inch filter as well.  Some filters are strange in their sizes as well and may be more expensive. SBIG has a 1.37 inch filter for some of their camera setups.

COST OF A FULLY AUTOMATED HOME OBSERVATORY:
The average home build observatory for a backyard observer, with modern automation and astrophotography and mounting options is often in the $90k to $110k price range.  The way I look at it, if I can enjoy HJRO, because I'm in the downriver area, I just saved the cost of building my own backyard observatory.  If you're visiting and taking a look through the schools telescope, you've just saved yourself a lot of money to get a nice view.  I personally buy telescopes that augment my observing at HJRO. I don't want to spend $5000 on a C14 setup for my own use and then spend an hour setting it up in my backyard.   I'd rather purchase a few small telescopes and have them as options for others to look through when they visit HJRO.  One advantage to joining an astronomy club is you can do group observing and look through different instruments and take your time, saving money perhaps and learning more about telescopes and options before you make a purchase decision.

WHAT IS THE BEST TELESCOPE DEAL
For some the best deal is to buy a used telescope.  Many get into astronomy and then they don't understand it or decide to get out of the hobby after some time.  They may offer a telescope used that has a lot of features figured out and they have done a lot of work on the setup or because they didn't stick with the hobby.  This can give a person a good deal and save you money, but you may want to hang around with others and visit clubs to learn a little more about what you really want and what telescope will meet your needs.  Different telescopes have different advantages and most astronomers end up buying more than one telescope for different viewing needs.  We often use the smaller scopes more often, because we don't want to take a lot of time to setup a telescope and quickly get a view of the sky.   And ironically as an astronomer gets older and may be able to afford a big dream telescope, our backs are older and we grow tired of carrying and setting up that big telescope.  So we often change our idea of the ideal setup and may purchase and buy and sell several telescopes over time.

PHOTOSHOP PROCESSING OF ASTRONOMY IMAGES.
We use techniques processing in photoshop that are much more detailed than a typical photographer would use. Some involve custom macro processes that are saved and sold as filter actions.

There are photoshop filter actions that can be bought online that perform some of these filter adjustments automatically to help a person speed up the processing of a astrophotograph.

- To tweak and process an image. (Something to do on a cloudy day.)
How much processing time will it take? You can spend a lit of time tweaking a photo. Some of our members have shown photos that took several hours or more to process. Some photos took more than 50 hours to process, and may have many layers showing different features of an object.

I have spent a few hours toying with a rather basic image of Jupiter and I'm just a basic beginner with astrophotography. Some members of our group show photos that took dozens of hours to edit.

We even have a special interest group that meets once a month a month in Dearborn Michigan, and some of us also meet in Plymouth once a month for a different astrophotography meeting.

The next astrophotography meeting will be this Thursday March 14th, at 5:30pm at Henry Ford Community College. Anyone can come in and visit. We have members showing their latest attempts at astronomy photography and they will often ask questions and give tips or ideas on how to improve imaging.

- VIDEO CAMERAS for astronomy
There are also Video cameras geared toward astronomy. These offer lower resolution images geared toward video. The Stellacam and Mallicam are two of the more expensive video cameras for astronomy use. These cameras cost between $800 and $1600. They often have the resolution of a webcam, an older webcam. Maybe 640 by 480. They may have black and white or color output. These video cameras use high sensitive video chips and have noise reduction circuitry built in. They may also have a frame buffer that stacks and amplifies the image making it much brighter. They may have exposure and gamma adjustments. They will allow bright real time viewing of faint objects. We have a Stellacam 3 at HJRO which is a video camera for astronomy.   The Stellacam provides a composite video output that can go to a TV monitor inside the observatory to show us live video of the objects we are looking at.  Our Stellacam has a video output but this model doesn't have USB digital output.

We can see video of the images but we can't record them unless we use a video recording package like a Dazzle card. Capturing Video decreases the signal to noise quality of the image, video has a low signal to noise ratio (62db).  This is much worse than the signal to noise ratio in a typical digital camera image, like a Canon EOS. That makes the images from a video camera, not very suitable for capture and processing.  We can get a quick image of that, we can record it as an AVI file and treat it like a webcam file, but the image quality will suffer compared to more expensive dedicated Astronomy cameras.  A video camera will have bigger pixels and offer great low light capability, which is good for live viewing on a TV monitor and also will show fainter, but lower resolution objects live.  This makes the Stellacam good for group viewing.

The image chip on a video camera for astronomy, at least the low end ones like the Stellacam, is small. This makes the camera act like w high powered 8mm or 6mm eyepiece. This gives high powered views but it gives a narrow field of view.

This means a wide image cannot be easily displayed with a Stellacam camera. We can see the moon with a low powered telescope and a Stellacam, but it will often be a part of the moon, not the full moon, because the power is amplified by the small chip sensor size. We are literally cropping the light image with the small sensor of the Stellacam and that makes the image larger.

I can show visitors from time to time the Stellacam at HJRO and show objects on the monitor. This is also nice for some astronomers who want a small telescope and setup. Some use a smaller telescope, like a four inch refractor instead of a large telescope, with a Stellacam, to do deep sky observing. They have found a video camera and a small scope can be as enjoyable and more portable than carrying some large telescope out to observe.

We have seen Pluto from HJRO using the Stellacam on the c14. Pluto is a 15th magnitude object and near the limits of seeing with a C14 and in bright skies it's difficult to see. Some say we could not see Pluto with the 14 inch telescope and our eyes on the eyepiece in our urban lit sky location. Bright skies reduce the ability to see faint stars due to increased sky glow. We were easily able to see Pluto on the video screen using the Stellacam. It looks like a faint star and is as faint as the small dim stars inside the ring nebula. We have seen those stars as well with the Stellacam, or in photos. But we haven't seen those stars inside the ring nebula with the C14 and our eyes on the eyepiece. So video cameras for astronomy can give you a view of fainter objects.

The cost of the telescope and mount.

There are a few ways to buy a telescope.

I'm going to give a few examples now of a typical telescope.
Let's say you want to buy a typical modern goto telescope and it has a mount and is computerized with motors. You might buy a C8 nexstar from Celestron for $1200. This will get you a goto mount that has motors and a computerized controller. It will have an alt/azimuth mount that aims up and down like a canon/artillery mount would move. Thus will goto stars for visual and track the stars with two axis movement. But it won't frame and change the frame of the stars the same way the sky changes because it's moving on two axis of movement. Where an EQ mount is tilted and matches the earths axis when setup correctly. So the EQ mount would reframe and match the sky frame as it's moving in the exact opposite direction of the earth turning on one axis aligned with the earth. So with a c8 and a nexstar mount you will not be able to take ling exposure photos. You can buy some nexstar telescopes like the c6 which is smaller and cheaper and they have a wedge adjustment to tilt the mount to make it tilted and in an EQ configuration. That will allow long exposures, but we have another problem.

Astrophotography requires precision that is much more precise than visual observing. If the mount shakes a little you can ignore it when your looking through an eyepiece. You will naturally see the image move, and then ignore the shake as the mount calms down. With a photo every shake or unwanted movement will cause the image to blur.  For long exposures we need precise tracking and a solid mount.  We often need a feedback which we call a tracking camera.  We also may need PEC error correction, which is a way to train the computer to change the speed of the motor for gear imperfections.  All these complex techniques take time and may add to the expense and learning curve to get great images.

Let's look at how a typical fairly expensive popular telescope is priced, the Nexstar c8. It might cost $1100 to $1200. Sometimes they are in sale for around $1000. The optics of the telescope on some of these may cost more than half the total price of the telescope package you purchase. A C8 tube might be $600 alone. The mount might account for $400 of the cost.  Of course Celestron spent less than $400 to manufacture that mount in China.

In astrophotography the telescope optics are important, but the size of the mirror and lens is not as important because we are gaining more light by using time lapse exposures. We don't need as large a mirror or lens for photography and the time lapse photos will show a lot more than our naked eyes will see when we look through a telescope.  So we can use a smaller telescope and a more expensive mount.   Astronomers on a budget wanting to take good photos will spend less on the telescope and more on the mount.  A general rule of thumb is 70 percent of the cost of a telescope setup is spent on the mount and 30% for the telescope.  This is the opposite of the expense in a typical entry level C8 telescope from Celestron.   Celestron, Meade and others will offer you more expensive options with more expensive mounts.  You can get a EDGE HD C14 for example with a $6000 mount and a $4000 telescope.  That is closer to a formula for astrophotography that will work, but that is an expensive setup.  Many astronomers will cut back on the size of the telescope and spend more on the mount, often buying certain quality name brand mounts, made in the USA or Japan.  Brands like Vixen, Takahashi, Losmandy and Software Bisque.  These mounts can be quite expensive.

If I spent $1000 dollars on a telescope and mount then the telescope should be worth about $300 and the mount should be an EQ mount and cost about $700.

For Astrophotography generally you are spending a lot more money on the mount.  A dime is one arc second when it's viewed by your naked eye at a distance of 3.5 miles.  That is the kind of accuracy that many astronomers are shooting for with astrophotography.

This is a basic explanation of some of the basics of astrophotography.

I have a few links about astrophotography below.

There are many more good links out there - easy to find in today's search engine.

Visiting an astronomy club or talking with an astronomer will often result in a long conversation and we love to talk about gear.

The first link below shows some basic articles by Sky And Telescope magazine on their web site.  They have a basic version of their magazine that is emailed out for free to the public.

The middle link below shows a site that has a DSLR DVD course book for sale. I bought one of these and found it very interesting and well worth the $40.  It's geared toward DSLR photography.  I learned as much about astrophotography from that one disk intro lesson, as I did attending 6 or 8 astrophotography meetings at our local FAAC club. To me that means this disk and lesson was a good value.

THE WIDE FIELD OPTION WITH FAST STAR
There are several other options as well. For wide field photography there is a rather expensive option from Celestron that offers very fast wide field imaging. That is called the fast star option or hyper star option, offered by starzona. That option allows sct users of Celestron telescopes to convert or use a telescope like the HD line of telescopes into an F2 camera. This allows the mounting of a camera in front of a c6, c8, c9.25, c11 or c14 telescope. The Fast star option is included in any Celestron HD telescope. But these are often in the $3000 to $4000 range at the low end. The fast star or hyper star lens fits in front of the telescope and the camera sits on the corrector plate, turning the telescope into a very wide field fast camera. It allows very fast exposures of deep sky objects.

(This option is available on many Celstron SCT telescopes and only one Meade telescope, the 14 inch Meade SCT.)

I've often thought of getting a fast star option on a HD telescope from Celestron. But these are in the $4000 range for a c11 on a cheaper EQ mount, and the hyper star lens is about $800 for the c11. The c14 at HJRO could be converted to a hyper star for about $400, as kits are available. But the hyper star lens for a c14 is about $1200. That would allow very fast imaging and wide field imaging. A c11 would be giving wide field 20 power views with a hyper star system. Very compelling as you could image at three different focal lengths using a field reducer for f7, a fast star system for f2 and the native f11 configuration.

If you only wanted to do wide field imaging and quickly get nice images a Celestron HD system with the hyper star option would be difficult to beat. But you are talking $4000 to $5000 to start without a camera.

It's nice to dream about equipment. Astronomers love to chat about gadgets.

- PROCESSING IMAGES CAN BE FREE AND RELATIVELY INEXPENSIVE - Grab a Hubble image from NASA and process away.

The most expensive images you can process are images that are available free from the Nasa website.

If you live in the USA, you already own a multi million dollar telescope that is out there in orbit. It's called the Hubble telescope and your tax dollars paid for it.  They have a catalog of images that anyone can download and process.

If you have a computer and want to focus on processing images, you can get images from NASA on their website.  Learn to download the raw (FIT) images from the Hubble telescope and use a common FIT expander available on the internet for your PC.  Then load the images up in an astronomy processing program and image processing program and edit away.

You can spend hours processing and learning how to process the best astronomy images. All it takes is a computer and some downloading.  If you come up with a great image, NASA and magazines might even publish it and give you photo credit as the processor.

I think I've covered some of the basics pretty well for a quick blog post. Three links are below.


http://www.skyandtelescope.com/howto/astrophotography

http://www.astropix.com/GDPI/ORDER.HTM

http://ghonis2.ho8.com/



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