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“In the silence of the night, the stars speak to us, reminding us of the infinite possibilities of the universe.”
-Ajaz Ahmad Khawaja
Introduction
At first glance, the night sky appears as a dark blanket interspersed by pinpoints of light little different from each other in any way. However, to the experienced viewer, the sky holds many hidden treasures that, although extremely difficult to see with the naked eye, can be fully appreciated with nothing more than a tube and a few carefully placed mirrors or lenses. A telescope is a powerful but often misunderstood tool of an astronomer that can make the most distant celestial objects visible, magnify the planets to reveal intricate details and even see in many parts of the electromagnetic spectrum the human eye can not detect at all. Unfortunately, telescopes can also lead to many frustrating nights for the amateur stargazer since many devices sold to new buyers offer little more than the ability to see a blurry planet or the craters on the moon.
The amateur telescope business represents a classic “you get what you pay for” market where the buyer should beware as cheaply made telescopes abound in the amateur market. Combined with the fact that many salespeople are poorly qualified when it comes to knowledge of the products they are selling, first purchases by the general consumer quite often end in hours of frustration rather than enjoyment. In the US, there are two major telescope producers for the (serious) amateur market: Meade Instruments and Celestron. It is worth mentioning that there are other manufacturers of inexpensive
Amateur stargazing if often a young person's first introduction to astronomy. Unfortunately, without the right equipment, untrained accompaniment with a telescope can quickly end in frustration and a loss of interest.
telescopes like Tasco, Orion and Jason but they are generally looked upon with disdain by the serious skywatcher and are of a quality that limits their effectiveness for anything but simple solar system observations. Between Meade and Celestron, these two companies produce all three major types of optical telescopes and are, in fact, fierce competitors in the market especially regarding Schmidt Cassegrain telescopes (pictured below).
What are you Paying For?
Two big factors influence the price of telescopes. The first is the quality of optics in the scope. Quality telescopes are extremely fine-precision instruments featuring the highest level of optics (lenses and mirrors) that are designed to not only look at the easy objects like the Moon and nearby planets but deep sky objects as well. In lower quality telescopes, the optics are usually of lesser manufacturing and/or mounted poorly in the telescope so that if the scope is strongly bumped or jostled, the optics will be knocked out of alignment rendering the telescope worthless.
The second factor weighing heavily on cost is the addition of computer controls. As modern computers become smaller and smaller, it has become possible to include huge databases of astronomical data within the telescope itself while the actual machining of internal gears, etc. allows the telescope to achieve the precision guiding necessary to track the database objects across the sky with ever decreasing levels of error. Computer controls, especially if they are not retrofits to older manual scopes, provide the telescope novice with an easy way to get started without really knowing how to guide a telescope across the sky. Its very much the same argument when you try to teach a person to use a compass or turn on a GPS.
Telescope Types
Telescopes are produced in three major designs: the refractor, the reflector and a special type called a catadioptric. Each of these telescope designs has certain advantages and disadvantages that are a result of how they are made and the way in which they focus an image in the eyepiece. The purpose of this particular discussion is to reveal the differences hidden inside the tube and to provide some guidance for the best type of scope for different stargazing opportunities.
The first type of telescope, the refractor, is the most common and easily recognized. Refractors consist of a long tube that uses a series of lenses to bring an image to focus in the eyepiece located at the back of the tube. They are often the first telescope purchased by an amateur since they are generally inexpensive, easy to use and are portable. Because refractors use lenses, they can also provide the most magnification of any telescope type without buying extra eyepieces (which are usually needed to magnify images with the other two types of telescopes). The major disadvantage of refractors (and its a big one for a serious stargazer) is that due to their narrow tubes, they are not able to focus large amounts of light into the eyepiece which is necessary to see distant objects like galaxies. In optics, the larger a device's opening (aperture), the more light gathering capability the device has but lenses get increasingly difficult to produce the larger they get so even in the professional telescope world, the largest refractor telescope on Earth (the 40 in. telescope at the Yerkes Observatory in Wisconsin) pales in comparison with the largest of the other varieties.
Reflector telescopes use a large primary mirror at the bottom of the tube instead of a lens to gather light and reflect it to a focus point located farther up toward the middle or front of the tube. When the reflected light bounces back up the tube, another small secondary mirror will reflect the light through a hole in the side of the tube and into an eyepiece (not out the back of the tube like the refractor). The most popular type of reflector is known as a Newtonian reflector named after Sir Isaac Newton who is credited with inventing it in 1681. The main advantage of a reflector over a refractor is that the reflector will often have a much wider aperture allowing for more light to enter the tube and hit the eyepiece. With more light comes the ability to see deep sky objects like galaxies much better than the refractor. From an engineering point of view, mirrors are also an easier device to fabricate than lenses so most modern telescopes use one or more interconnected mirrors rather than lenses. The biggest disadvantage to using reflectors lies in their potential size. Reflectors are often much larger than refractors (like this backyard version in New Zealand) making them harder to transport to new locations if so desired.
Catadioptric telescopes are actually not as complicated as their name might indicate. These telescopes combine both the characteristics of reflectors and refractors into one tube making them the most versatile type of telescope of the three. The most popular type of catadioptric telescope is known as the Schmidt-Cassegrain (SC) and creates an image by sending light through a special large lens at the front of the tube (like a refractor) into a primary mirror at the back of the tube (like a reflector). However, one of the special features of an SC telescope is that the eyepiece is at the back of the tube. If this is true, how does an image get to the eyepiece if it reflects off the mirror also located in the back of the tube? Herein lies the feature that makes an SC telescope different than the other two types.
First, the lens at the front of the tube (called a corrector plate) has a secondary mirror embedded into the middle of the lens facing into the tube. If you recall, the secondary mirror of a reflector telescope is the one that sends light into the eyepiece. As the light from the primary mirror hits the secondary mirror, the light is then sent back into the tube through a hole that exists in the center of the primary mirror. Once the light goes through the hole in the primary mirror, it is then focused into the eyepiece also located at the back of the tube. The next question should be "why"?
The special design of an SC telescope allows this scope to use the best features of each of the other telescope types. First, since the SC telescope bounces an image twice inside the tube instead of once like the other telescope designs, it can be half the length of normal reflector or refractor and still produce the same quality images. This feature makes the SC telescope highly portable. Second, since the telescope uses a large primary mirror at the back of the tube, SC telescopes often have quite wide tubes allowing for all of the light gathering ability of a reflector but without the very long tubes that make reflectors difficult to move around. The basic SC concept is often the design of choice for some of the world's largest modern telescopes (see below). Although it is nowhere near the largest telescope ever built (a common misconception), the Hubble Space Telescope and its 94 in. primary mirror is also of a Cassegrain design. However, all these features are not without one big disadvantage, price. Of the three types of telescopes, SCs are by far the most expensive and are quite often out of reach for many amateur stargazers. Prices well over $3000 are common for larger aperture, computer-controlled telescopes of this variety.
A typical reflector telescope with its tell-tale, side mounted eyepiece. This particular telescope, a Celestron NexStar 130, is computer controlled.
The Meade LX200, a Schmidt-Cassegrain catadioptric telescope. This computer controlled telescope is identical to the two telescopes owned by UDHS. Newer version (like the one shown) even have built-in GPS sensors for precision alignment no matter where the user might set it up.
Telescope Terms
Hopefully, you are beginning to realize that telescopes are actually simple devices that utilize either lenses, mirrors or a combination of both inside a long tube to focus light into an eyepiece so the viewer can see the image and, in spite of their design differences, all telescopes share a few common terms that are also found when working with cameras and other optic devices like microscopes. First, recall a telescope's size is always referred to by its aperture, the size of the scope's main mirror or lens. Apertures are usually measured in millimeters, centimeters or inches. Focal length describes the distance between the main mirror or lens to the focus point at the eyepiece. Focal length is measured in the same units as aperture. Focal ratio is a mathematical calculation found by dividing the telescope's focal length by its aperture. Focal ratio is usually referred to as an "f/number" (for example: a telescope with a focal length of 40 in. and an aperture of 8 in. would be known as an f/5 telescope). The lower the f/number, the more light that enters the telescope. This measurement should be familiar to anyone who has ever operated a manually controlled single reflex lens (SLR) camera.
Magnification of a telescope is actually quite difficult to determine since the magnification of an object can occur at two locations in the telescope. First, magnification can occur as light is passed through lenses in the tube of the scope (like a reflector). Magnification can also be produced in an eyepiece on any telescope design since they also have a series of lenses inside them. In fact, some eyepieces available for amateur telescopes quite often have between 4-8 lenses packed inside! In order to determine the magnification of a telescope, the focal length of the telescope and the eyepiece is needed. To determine the total magnification, a user must divide the telescope's focal length by that of the eyepiece (making sure all units of measure are the same since many American telescopes use inches for the telescope's focal length but eyepieces are almost always measured in centimeters). For example, a 6-inch, f/8 telescope has a focal length of 48 in. (1,200 mm). If a 25mm eyepiece were placed on this telescope, the scope would be able to magnify an image 48x. A 12mm eyepiece would magnify an image 100x. This is also the reason that each time an eyepiece is changed, minor corrections are needed to focus the image since changing the eyepiece changes the lenses used which changes the focal length. Regardless of the magnification however, it is vital to remember that the more an image is magnified, the dimmer the image becomes since the object's light is being spread over a larger area. Highly magnified images are also very difficult to focus. Since most amateurs think magnification is the most important feature of a telescope (WRONG!), salespeople (especially those who know little about telescopes) will advertise and attempt to sell a telescope based on high magnification and the unwary buyer will often go home
with a device that is good for little other than looking at the moon or a nearby planet like Jupiter and Saturn. As a general rule, a telescope should not magnify any more than 60x for each inch of aperture the scope has. Remember, aperture, not magnification, is the most important feature of a telescope.
Telescope Components
Regardless of design, all telescopes consist of the same basic parts. First, all telescope components are either placed inside or on the outside of the tube. Depending on the type of telescope, the focusing components will be slightly different from each other as light enters the tube of the scope. On refractors, an objective lens is found at the front of the tube which passes the light on to secondary lenses usually found in the eyepiece at the back of the tube. In a reflector, a primary mirror located at the back of the tube reflects light to a secondary mirror which then focuses the light in the eyepiece. In an SC or other catadioptric telescope, a primary mirror located at the back of the tube will send light into the corrector plate at the front of the tube which bounces the light again to the eyepiece at the back of the tube. In all cases, the eyepiece is any of a variety of devices used in order to see an image. May times, eyepieces are interchangeable and can be bought separate of the telescope. Optics is a general term often used when describing any of the above components.
Telescopes are an excellent example of getting what you pay for. If the price is cheap, so is the telescope. An actual review of the telescope shown above included "...If you buy this with the intention of getting a child interested in astrology, please take the time to buy something they can use..." Astrology? Let the buyer beware!
On the outside of a telescope, many different devices may be found depending on the features of the scope. First, all telescopes will have focusing knobs on or near the eyepiece that are used to bring an image into focus for the eye. Occasionally these knobs will be located on the end of long flexible cables attached to the mount. Slow motion controls will be present on better telescopes to allow very specific, slow movement of the scope in a similar way to similar controls on a microscope. If the telescope is computer controlled, all movements are probably accomplished electrically. This movement is very useful when viewing planets or other objects that could be lost if the scope is bumped or moved quickly. Also on better scopes will be a viewfinder. Viewfinders are small magnifying scopes mounted on the sides of the major telescope itself and serve the purpose of assisting in finding objects that would be difficult to see with just the telescope itself. Finding stars and planets with just the telescope can be very difficult.
Finally, next to the telescope itself, the most important component of a scope is its mount. Usually a tripod, the mount of a telescope is the most often ignored component of the scope. Without a sturdy mount, even the best telescopes will be useless since they will wobble, sway and even collapse at even the slightest touch. Since they are lightweight and highly portable, refractors are the scopes most likely to have low quality mounts. A telescope with such a problem should never be purchased for astronomy observations.
A typical refractor telescope (in this case a Meade 90AZ) showing the cable-attached focusing knobs and attached viewfinder. The mount is also of significant size and weight to allow for this small scope to maintain a steady view of celestial or terrestrial targets.
Mounts come in two general types. The first is called an altitude-azimuth mount (alt/az) and the second is known as an equatorial mount. Alt/az mounts are the most common and are found on almost all refractors and many SC telescopes. They are named since they allow the scope to move in two directions: up and down (the altitude) and side to side (the azimuth). When an object moves out of the view of the eyepiece, the telescope is moved on both axes to center it again. In a sense, they move in exactly the same way as a child's Etch-a-sketch. But...the sky does not move in the same manner. Since the Earth rotates in a circle, objects in the sky appear to move in arcs, not stair-step increments. Because of this, long exposure pictures of deep sky objects are extremely difficult to take without the images becoming blurry since the telescope does not mimic the movements of the object which is why many serious astronomers and astrophotographers prefer equatorial mounts in spite of their more difficult setup. All hope is not lost on the alt/ax mounts, however. In fact, many of today's alt/az telescopes (especially the computer controlled ones) now use gears that have teeth so small, they can almost perfectly mimic the arcing motion of the sky in spite of their movement limitations. Or, as a second option, artificial devices called equatorial wedges can be installed at the base of the telescope to imitate a true equatorial mount (see below).
"Cheating" with an alt/az telescope. At left is a standard setup for the Meade LX200 telescope as an alt/az mounted telescope. It should be easy to realize the telescope can only move straight up and down or rotate left or right. If the internal gears are high enough quality (they ARE in the LX200), the telescope can still closely mimic the motion of objects in the sky by making extremely small vertical and horizontal corrections simultaneously. However, for the most precise movement, certain alt/az telescopes can be turned into equatorial mounts with the use of a device called an equatorial wedge. Pictured at right, the wedge is the large angled piece of metal mounted between the tripod and the LX200 telescope. This wedge must be set up to point precisely at the North Star in order to work properly but if it is, the normal movements of the LX200 will now effectively imitate the normal arc movement of the sky.
The more accurate equatorial mount is found on most reflectors and more expensive SC telescopes. These mounts, while they must be set up in a very particular way (which makes the initial setup a bit more complicated), allow the user to swing the telescope in only one motion when it needs to be moved. The whole idea behind an equatorial mount is that it will swing in an arc in the exact same pattern as the sky. These mounts are easily spotted since, in reflectors at least, a large rod ending in a counterweight sticks out from the telescope to offset the weight of the swinging scope. The "complicated setup" problem with equatorial mounts lies in the fact that, in order to actually get the telescope to swing in an arc that exactly matches the movement of the sky, the scope must be lined up precisely according to the North Star. This then requires the user to have some idea of how to navigate using the stars in order to identify Polaris in the first place. By comparison, an alt/az mount can just be setup in a field in any manner...no exact alignment with North is required. While quite expensive and very heavy for larger reflector telescopes, equatorial mounts are the most accurate for tracking long time movements of stars and other celestial objects.
The UDHS Meade LX200s
UDHS possesses two Meade 8" LX200 GPS catadioptric telescopes. The LX200 series represented the top of Meade’s line of amateur telescopes when they were purchased and were among the first fully computer controlled telescopes of their kind on the market. To this day, the original design has been upgraded for newer models (adding the GPS for example) but the basic construction has remained the same since their introduction back in 1998.
For purposes of setting up and using the LX200s, pay extra attention to the "caution notes" (denoted by the red font) as these highlight particularly difficult to use or fragile components of the LX200.
LX200 Components
Tripod
Why explain a tripod? Because it is the most often overlooked component of a good telescope. The LX200s tripod is a heavy and sturdy mount that can keep the scope steady in even mild winds. In particular, though, attention needs to be brought to an especially annoying piece of the tripod assembly called the C-clip. Perhaps the weakest part of the entire assembly, the C-clip fits over the threaded screw which the telescope connects to during assembly. Used to keep the telescope from wobbling when on the tripod, it is
The Meade LX200 GPS Schmidt Cassegrain telescope. UDHS acquired two of these telescopes through a grant in 2002.
especially easy to bend or even break when threading the telescope on to the tripod. So when connecting the telescope to the tripod, listen and feel your way on to the screw and stop threading it when it feels tight so the C-clip does not (hopefully) get damaged. These clips are not expensive to replace (we have about a dozen of them) but they are difficult to find.
Viewfinder
Since it’s very difficult to “dead eye” an object like a star from the back of the tube, a viewfinder is a handy, non-magnifying device that can be used to quickly find objects in the sky and, when properly aligned, save lots of time better spent at the end of the eyepiece. The viewfinder attaches easily to the side of the tube in a track and is tightened with two screws. However, each time the viewfinder (sometimes called a spotting scope) is put on the scope or taken off, it needs to be realigned with the scope to ensure they are, in fact, looking at the same spot in the sky. To be truthful, this can be a time consuming process but is a necessary evil before going skywatching. Here’s how to do it...
First, set up the scope and focus on a distant, ground-based object by looking through the telescope itself. After you have identified the object, manipulate the set screws that control the viewfinder so that its crosshairs are pointing EXACTLY at the same spot as whatever is in the exact center of the eyepiece. Getting this right during daylight hours is also a “trick of the trade” as nighttime aligning is very difficult. From then on out, use the viewfinder to point at objects in the sky and hopefully you will be able to easily switch over to the eyepiece and see the same thing. A word of caution though...the screws that adjust the spotting scope are arranged in two sets of three which makes moving the spotting scope in the direction you want challenging. They are also made of plastic and have broken in the past so it is important not to overtighten them. Finally, one screw in particular rests very close to the GPS receiver making it very difficult to adjust.
Another version of the spotting scope that we have for the LX200s is the EZfinder, a battery operated viewfinder that emits a small red dot in a small portal when turned on. Its adjustments can be made with small knobs located along the device. Depending upon what else the telescope has recently been used for, the mount for the EZfinder may or may not be attached to the tube.
Microfocuser
The microfocuser is a peculiar device only used on the LX200s which is why it is being introduced here. Designed for especially fine focusing, the microfocuser is a small gearbox that can be attached to the back of the telescope tube and then used to attach to a prism, eyepiece, etc. It is powered so must be plugged into the LX200 console in order to work but provides extremely fine focusing adjustments without actually touching the telescope, something that can be very useful for very specific viewing. It should be noted that the microfocuser does not have to be used in order for the telescope to function but its use has been found to be convenient for focusing.
Autostar Controller
The Autostar controller is essentially the brains of the LX200 and all of its databases, computer controls, etc. are stored in the controller. Although it is powerful, it can be difficult to use at times and, in cold weather, its red digital
The LX200 microfocuser (C) is attached to a threaded ring (B) and tightened by three allen screws. Other components can be added to the back of the device as the user desires.
display can be tough to read if it is scrolling a message. However, for its little quirks, it is a powerful tool and is inserted on an arm-looking bracket that can be installed on to the left fork arm handle of the telescope after it is connected to the tripod.
An Alt/Az Mount with a Catch
One important aspect to remember with the LX200 is that although it has an alt/az mount, it is still an exceptional telescope for use in long exposure astrophotography and star tracking. In most cases, alt/az mounts can be problematic because of they can not “sweep” in arcs across the sky like an equatorial mount. They instead have to rely upon small up/down and side/side adjustments. If you are familiar with an etch-a-sketch and ever tried to draw a true curve, it’s the same problem. However, part of the excellence of a scope like the LX200 is that its gears contain literally thousands of tiny teeth across its circumference so the fine tracking of the scope is so accurate it essentially mimics a true arc. Since the scope can do this, it is still an effective tool for astrophotography where precise focus on an object for an extended period of time is essential.
Sticker Shock
Amateur astronomy is a lot like golf in that, you may have the best bag in the world but without the clubs, the bag isn’t really worth much. Astronomy is the same way. The LX200 is a top of the line scope but without all of the other components that go with it, the scope will not be able to be used to its full potential. Unfortunately, these “accessories” are also precision instruments that carry a matching price tag. Here are a few of the accessories we use at UDHS.
Eyepieces
For every occasion, there’s an eyepiece. Generally, the differences between them lie in how many lenses they are equipped with which in turn effects their magnification, light gathering capability and focal length. Of particular note is one eyepiece we use called an illuminated reticle. This eyepiece is either equipped with a small battery or a cord which plugs into the main telescope console and provides a faint red crosshair that the user can see when looking through the eyepiece. It is especially effective when trying to precisely line up the telescope with the viewfinder. Eyepieces come in two barrel sizes, 1.25" and 2". Although the LX200 can accommodate either size, the 1.25" is generally more common and is the size of all UDHS eyepieces.
Prisms
Prisms are a necessary tool and usually connect with the telescope on one end and an eyepiece on the other so the user does not have to actually look in the back of the tube to see through it. Generally, they are found in two forms; 90o and 45o. The 90o prism comes with almost every scope so its basically “free” but shows images upside down and backwards making fine adjustment of the telescope a bit annoying. So, to correct this, a user can buy a separate 45o prism which flips the image right side up and correctly left to right. Any way you look at it, you will need a prism.
Filters
Like eyepieces, filters come in all kinds of shapes and sizes with each use slightly different although none of them are really necessary for decent skywatching. For purposes of this discussion, there are essentially three kinds of filters that we use at UDHS. The first are color filters (shown at right). Color filters are specially designed to block out certain wavelengths of visible light in order to bring out others. They are especially useful when viewing planets and the Moon filter (not actually a color filter) is almost a must if you do not want to walk around with a bright dot in your eye for an hour after looking at it. The Moon is actually quite interesting to look at but because of its intense brightness through a telescope, it should always be the last object to look at since it will utterly destroy a user’s night adjusted eyes. These filters are 1.25" in diameter and thread easily into the back end of an eyepiece.
The second type of filter is useful if the user has some particular “specialty” observation he/she wants to make. For instance, in an area with excessive light pollution that can create a glare in the telescope, a user might want to use a “pollution filter”. These come in several varieties and are specifically to block out certain wavelengths that might contribute to atmospheric light pollution. UDHS has several of these and although the differences through the eyepiece are subtle, they can be useful especially in Summer when light pollution is typically the strongest. Other specialty filters are often used when looking at the Sun when a user might want to focus in on prominences and solar flares. However, any filter of this kind MUST be used in conjunction with the last type of filter featured next.
Finally, there are solar filters. EXTREME care should be taken when applying solar filters since a mistake can cause irrevocable damage to a user’s eyes or the instruments. As opposed to other filters, solar filters are placed at the front of the tube and are therefore purchased at a size matching the diameter of the tube itself. It is vital that the Sun’s light be filtered out before it enters the telescope since if it is focused through an eyepiece, it can actually melt the inside components of the telescope. Remember burning leaves with a magnifying glass? It’s the same concept. Even a small amount of the Sun’s rays focused through the telescope can cause great damage so solar filters should always be inspected for cracks, nicks, scratches, etc. prior to use. When inspecting a solar filter, no light of any kind should penetrate the filter. Most of them essentially look like a mirror. If there is a doubt about the filter’s condition, don’t use it! Finally, after the solar filter is firmly placed on the telescope and the scope is pointing toward the Sun, place a piece of paper or use a hand and place it above the eyepiece. No light should shine through. If it does, the filter is damaged and the scope should be moved off of the Sun right away to avoid damage.
Condensation Shields
Ever steam up a cold window with a warm blast of air? The same thing can happen to telescopes if they are suddenly moved from a warm environment to a cold one as water vapor that is naturally in
Various filters for use with the LX200 telescope. FRom top to bottom: Color filters, pollution filters, solar filters. Note the solar filters are placed in front of the telescope rather than at the eyepiece.
the tube condenses on the optics and clouds over an image. To help control this, UDHS has a device known as a dew zapper that wraps around the tube right at the point where the outer glass covering is located. This device, when plugged into a power course, supplies just a bit of heat to warm the tube in the area where condensation usually occurs and can greatly extend the amount of time a telescope can be brought outside in the Winter. Quite often, if users know they will be outside in cold weather, they will bring the telescope outside well in advance of the viewing time to let the scope acclimate itself to the temperature drop.
Portable Power Units
Actually a rather generic device, PPUs can be a user’s best friend since many more advanced telescopes and numerous accessories all require power to work to their fullest capability. Its not out of the ordinary to see serious amateurs with Honda generators. Especially on cold nights, telescopes can be battery hogs and even car batteries will not last long if the scope and numerous accessories are all running at the same time. UDHS has two power systems that can be used to augment the telescope's internal batteries. First, there are two PPUs that can run up to two accessories with cigarette lighter adapters on them. We usually use these for the dew zappers. They also have flashlights built into them of which one of them is equipped with a red lens for adequate lighting without losing much light sensitivity (red light is not as damaging to human night vision as white light). Second, we also have a power inverter which is actually contains two standard 110 volt attachments that can be then be connected to a portable car battery or inserted into a vehicle’s cigarette adapter. This is typically used to power the telescope and a laptop computer although these devices will require the car to be running to avoid completely draining the car’s battery. In 2011, a gas Yamaha generator was added to the inventory as well.
Camera Adapters
Astrophotography is a difficult but potentially rewarding offshoot to standard skywatching and since a camera can see colors, etc. that the human eye can not, many amateur astronomers eventually get into this field. For standard SLR cameras, the lens is removed and the telescope behaves like the lens. However, to accomplish this, the camera needs a two part connection to the telescope. The first part is called the T-adapter and attaches to the back of the telescope. This component in turn attaches to the second half of the connection which is specific to the brand of camera used. The camera attachment would connect to the body of the camera like any standard lens. There are two things to keep in mind about using a standard SLR camera. If you have ever used one, you know that when you look through the camera, the image appears much darker than it actually does. This is the result of what is called the “screen”: inside the body of the camera and if the standard screen is used for astrophotography at night, it is very difficult to see dim objects when using the camera like an eyepiece.
The second form of astrophotography has now reached the point where it can readily compete with the same color saturation as print film. You know
A Meade Pictor CCD imager. The ridged pattern on the back of the imager acts as a heat sink much like those found on computer processors.
this technology as a digital camera but in astrophotography it is known as a CCD imager. CCD stands for “charged coupled device” and is exactly the same (electronically) as a regular digital camera but is designed to fit on the back of a telescope and use a computer and software to control the photography. UDHS has a basic CCD imager made by Meade which easily attaches on to the back of the telescope tube but requires a computer in order to run.
For Every Occasion
For just about any type of telescope use, there are special attachments and devices that can be used to make the experience worthwhile and often (easier). Serious telescope use does come with a steep learning curve and some less serious amateurs often lose interest after a short period fo time without proper tutelage. However, it can also be very rewarding and a user should always keep their eyes open for new devices to increase capability and results.
Files and Downloads
CCD Imaging: How to Image the Digital Sky
Bootes, Corona Borealis and Serpens
Capricorn, Delphinus and Aquarius
Files and Downloads
Orion, Orion Double Stars, Orion's Sword
Pegasus, Pegasus and Aquarius: Messier Hunting
Little Known Planetary Nebulae
Sagittarius Teapot, Sagittarius Cloud 24
Ursa Major, Ursa Major Deep Sky Highlights