What is the right telescope for me?
This is a common question people ask when they are looking to get into amateur astronomy. The answer depends on what is their goal in buying a telescope, and of course, how much money they are willing to spend.
There are three fundamental types of telescopes - refractors, reflectors, and catadioptrics - each with advantages and disadvantages. I will give a brief discussion of the advantages and disadvantages of the three types of telescopes.
Refracting telescopes or refractors are the most common type of telescope for beginners. They consist of a long tube with a lens at the top to focus the incoming light into an eye piece at the bottom.
Advantages of Refractors:
* Refractors are the most rugged telescope design, making them a good choice for children.
* Refractors are reliable, require little or no maintenance and are easy to use.
* They are a good choice for terrestrial viewing and for lunar and planetary observing because they offer high-contrast images.
* The most expensive refractor (APO refractor) produces the brightest and sharpest images of any comparably sized telescope.
Disadvantages of Refractors:
* Refractors are more expensive than the same aperture size reflectors or catadioptrics. Above a 3 inch aperture, the refractor price goes up quickly.
* They are heavier and bulkier than the same aperture size reflectors or catadioptrics.
* Refractors are less useful for faint deep-sky objects than reflectors or catadioptrics.
* There are many small "department store" refractors on the market that are poor quality. A beginner may quickly out grow or become bored with such a small refractor.
A reflecting telescopes or reflectors consists of an optical tube with a large mirror at the bottom of the telescope that focuses light onto a small mirror that reflects the light into an eyepiece located near the top of the telescope. The Newtonian reflector is the oldest and still the most popular reflector telescope.
* Reflectors are excellent telescopes for faint, deep-sky objects like nebulae and galaxies.
* Reflectors are less expensive than the same aperture size refractors or catadioptrics. They offer the most telescope for the money.
* They exhibit less optical aberrations than comparable priced refractors.
* Usually a beginner in astronomy will not out grow a medium-sized reflector telescope as quickly as equally-priced, small refractor.
* Reflector telescopes are more fragile than refractors or catadioptrics designs. A Newtonian reflector is open at the top and thus the mirrors can be exposed to dust and dirt and need periodic cleaning.
* There is a slight light loss due to obstruction from the secondary mirror.
* Reflectors are usually not used for terrestrial observation.
Dobsonian telescopes are large (6 inch or larger) Newtonian reflector telescopes with simple Dobsonian mounts.
* Excellent telescope for faint, deep-sky objects, such as galaxies millions of light years away.
* A Dobsonian is the largest telescope for the money. A hugh 10 inch Dobsonian can be bought for under $600.
* Easy to set up and use.
* Amateur astronomers wll not outgrow a large Dobsonian telescope.
* Dobsonian telescopes are quite large and heavy. They may be a problem to transport.
* A Dobsonian mount is a manual mount, thus it requires constant adjustment to keep the object in the eyepiece. This makes the Dobsonian not as useful for astrophotography.
Catadioptric telescopes are a compound telescope design that use a combination of mirrors and lenses to achieve a long focal length in a short tube length. They have features of both a reflector and a refractor but are considerably more compact than either design. The two popular catadioptric designs are the Schmidt-Cassegrain and the Maksutov-Cassegrain. The only difference between the Schmidt Cassegrain and the Maksutov-Cassegrain is in the shape and size of the corrector plate lens at the top of the telescope. The Maksutov-Cassegrain have apertures from 3.1 to 8 inches and the Schmidt-Cassegrain are 6 inch and larger.
* Catadioptrics are the best all-purpose telescopes. They achieve many of the advantages of both refractors and reflectors without the disadvantages.
* Catadioptrics are easy to use, compact, durable, and portable.
* Catadioptrics produce excellent, sharp images for deep-sky observing and are very good for lunar and planetary observing. Their image quality is second only to the finest refractor.
* Maksutov-Cassegrain telescopes are a superb design for small telescopes. They are excellent for terrestrial viewing and are very popular for spotting scopes. They have the best near-focus capability of any design.
* Catadioptrics are usually more expensive than reflectors of the same aperture.
* Catadioptrics have small amount of light loss due to the obstruction by the small secondary mirror. Thus images are not quite as bright as a high-quality reflector.
* Catadioptrics images are not quite as sharp as a high-quality refractor.
Some Buying Recommendations:
1. If portability is not important because the telescope will not be moved often, then you should consider buying the largest aperture telescope you can afford. The telescope's light-gathering ability, as determined by its aperture, plays the most important role in determining how much you will see. A good example of a low-cost telescope with a large aperture is a Dobsonian telescope.
2. If portablity is important because the telescope will be transported to a dark sky area for observing, then you should consider buying a compact catadioptrics telescope, such as a Maksutov-Cassegrain or Schmidt-Cassegrain rather than a reflector or refractor. Catadioptrics are the most compact and portable telescope design.
3. It is important to buy a solid mount for your telescope to keep it from being wobbly and hard to use. Two excellent mounts are the Dobsonian mount for the Newtonian Reflector and the German Equatorial mount for all types of telescopes and astrophotography. Solid Goto computerized mounts are also German Equatorial mounts.
4. If you want quality images of the planets but money is tight, a Maksutov-Cassegrain is a great choice. An Apochromatic (APO) refractor, such as an ED Triplet, will produce higher-quality images of the planets, but an APO refractor will be much more expensive than a Maksutov-Cassegrain telescope.
What should I expect to see with my telescope?
Our nautical telescopes are designed for terrestrial viewing and the Moon. They are not designed from amateur astronomy. With our astronomical telescopes, you can view solar system objects such as the Moon, the Sun (with a solar filter), the planets, and comets. You can expect to see some of the surface features of Mars, Jupiter and Saturn. In our Milky Way galaxy, you can see variable stars, double stars, star clusters, and bright nebulae. You can also view deep-sky objects, such as nearby galaxies and galaxy clusters.
What size telescope aperture should I buy?
In general, you should buy the largest aperture telescope that you can afford. This is because a larger aperture collects more light resulting in a higher useable magnification and higher resolution to see fine detail. The practical magnification limit is between 30-50 times the aperture size depending on the viewing conditions. For example, a 4 inch aperture has a practical magnification less than 200X under most conditions.
What tablet model are you using for this set up? Also how do you power the camera and the tablet? I been trying to make a set up like this for my telescopes, specially when I do outreach programs at schools. If is not to much trouble please let me know more about your set up I will be really appreciated Thank you.
I am using a Toshiba Encore WT8-A32 8", 32GB Tablet Wi-Fi 8" Atom Z3740 Quad Tablet. I bought it on eBay for $160 plus $12.75 S/H.The tablet needs to have windows OS. The Android OS will not work with telescope digital eyepiece cameras. The camera is powered by the tablet. Power is enabled when the camera software is connected to the camera to begin capturing images. The tablet gets power from its Lithium-ion battery (average battery life is 6 hours). http://www.ebay.com/itm/Toshiba-Encore-WT8-A32-8-32GB-Tablet-Wi-Fi-8-Atom-Z3740-Quad-Tablet-/161403194088?pt=US_Tablets&hash=item2594614ae8
I needed to buy a small Micro USB OTG to USB 2.0 Adapter cable that connects the camera to the tablet. I found it for $1.46 on amazon.com. This cable makes the tablet a host so it can provide the power to the camera. http://www.amazon.com/eForCity-Micro-USB-OTG-Adapter/dp/B005QX7KYU/ref=sr_1_1?s=electronics&ie=UTF8&qid=1363012431&sr=1-1&keywords=micro+usb+otg+cable&tag=androidcentral00-20
The driver software for the camera comes on a CD. I needed to transfer the software to a thumb drive to install it on the tablet. I bought a tablet holder / mount from eBay for $16.76. (http://www.ebay.com/itm/Lazy-Bed-Desktop-Stand-Tablet-Holder-Mount-for-iPad-2-3-4-5-Samsung-Galaxy-10-1-/311014170186?pt=US_Tablet_eReader_Mounts_Stands_Holders&hash=item4869e39e4a) The holder works wells but the C-clamp does not close down far enough on the thin tripod tray, so I needed to use a shim to tighten the C-clamp. After I collected the hardware, the tablet worked right way to capture real-time images from the telescope. This is a great way for your entire class to see the images from the telescope at the same time