Comparison with other cheap telescopes
From Scope F70076
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It is the rule, that a reflector with the same aperture, always costs less than a refractor. This is true also concerning the cheapest telescopes. A 60mm refractor costs almost as much as this telescope, all 70mm refractors are much more expensive. So it is likely the best choice for the cheapest telescope. Refractor is not better than reflector, except some expensive apochromatic refractors, and in a reflector with the same aperture less light would be lost. Some say that the colors seen through the refractor seem "softer" or such, but the difference can only be very small, and also reflector shows the colors as they are, but an achromatic refractor has some chromatic aberration, so that the yellow stars may seem reddish, you cannot exactly see the natural color. The secondary mirror obstruction for this telescope is only 7% by area, which means that this telescope has a 70mm "clear aperture". The biggest advantage of refractors seems to be that they almost don't need any maintenance, and they are also almost eternal, while the reflector's mirror would corrode after 30 or so years. But the maintenance like collimation of the reflector telescope is not difficult at all, and is some fun also, so being maintenance-free may be important only for these who know nothing about any technical things, I would not agree to have more than 10mm less aperture for that reason, and it is not so extremely important for me that a cheap telescope would be inherited by my grandson. | It is the rule, that a reflector with the same aperture, always costs less than a refractor. This is true also concerning the cheapest telescopes. A 60mm refractor costs almost as much as this telescope, all 70mm refractors are much more expensive. So it is likely the best choice for the cheapest telescope. Refractor is not better than reflector, except some expensive apochromatic refractors, and in a reflector with the same aperture less light would be lost. Some say that the colors seen through the refractor seem "softer" or such, but the difference can only be very small, and also reflector shows the colors as they are, but an achromatic refractor has some chromatic aberration, so that the yellow stars may seem reddish, you cannot exactly see the natural color. The secondary mirror obstruction for this telescope is only 7% by area, which means that this telescope has a 70mm "clear aperture". The biggest advantage of refractors seems to be that they almost don't need any maintenance, and they are also almost eternal, while the reflector's mirror would corrode after 30 or so years. But the maintenance like collimation of the reflector telescope is not difficult at all, and is some fun also, so being maintenance-free may be important only for these who know nothing about any technical things, I would not agree to have more than 10mm less aperture for that reason, and it is not so extremely important for me that a cheap telescope would be inherited by my grandson. | ||
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| + | Using binoculars instead of a telescope is another option. I wouldn't say that it is a bad advice to use binoculars, though in the conditions of light polluted skies one likely cannot see much with binoculars either. I don't have binoculars so I cannot compare, but telescope enables to see things much larger, which is important, as the objects like planets look very small even through telescope eyepiece and this makes it much easier to see any details. Using binoculars may be convenient, but would not give an experience of using a telescope. Almost all telescopes have quite narrow field of view, and it is important to learn how to find objects with instruments like these. Thus it can be said that binoculars are just a different kind of instrument, it doesn't make so much sense to discuss what of these is better, telescope and binoculars are just different kind of instruments, both giving a different experience. I think these who want a classical experience of using telescope, should buy telescope. Even better may be to have both. | ||
If you can waste more than $100 for a telescope, consider more powerful pure Newton reflectors, such as the 6 inch Orion SkyQuest XT6 [http://www.telescope.com/control/product/~category_id=classicdobs/~product_id=09185]. The XT6 weighs already 16 kg, maybe you may also consider a 8 inch telescope, but carrying a telescope bigger than that would be more like carrying furniture, a big undertaking, which you would not do just to quickly check something, and therefore such telescope would be much less useful. I have found only one similar telescope which should be available in Europe, the 6 inch Sky-Watcher Dobsonian [http://www.skywatchertelescope.net/swtinc/product.php?id=50&class1=1&class2=106], there is also a similar 8 inch telescope. An 8 inch telescope would enable you to see some 2 magnitudes more than this telescope, in all conditions, and 2 magnitudes more makes a lot of difference. Thus if you have to decide what telescope to buy, maybe start from determining the visual magnitude limit in your location, ie determine what is the magnitude of the faintest stars which you see with the naked eye. As much as I can tell, this telescope in the location with good visibility should be almost equivalent to 8 inch telescope in my location, and thus would likely show clearly most of the Messier objects. So the visibility in your location is the most important in deciding what telescope to buy. | If you can waste more than $100 for a telescope, consider more powerful pure Newton reflectors, such as the 6 inch Orion SkyQuest XT6 [http://www.telescope.com/control/product/~category_id=classicdobs/~product_id=09185]. The XT6 weighs already 16 kg, maybe you may also consider a 8 inch telescope, but carrying a telescope bigger than that would be more like carrying furniture, a big undertaking, which you would not do just to quickly check something, and therefore such telescope would be much less useful. I have found only one similar telescope which should be available in Europe, the 6 inch Sky-Watcher Dobsonian [http://www.skywatchertelescope.net/swtinc/product.php?id=50&class1=1&class2=106], there is also a similar 8 inch telescope. An 8 inch telescope would enable you to see some 2 magnitudes more than this telescope, in all conditions, and 2 magnitudes more makes a lot of difference. Thus if you have to decide what telescope to buy, maybe start from determining the visual magnitude limit in your location, ie determine what is the magnitude of the faintest stars which you see with the naked eye. As much as I can tell, this telescope in the location with good visibility should be almost equivalent to 8 inch telescope in my location, and thus would likely show clearly most of the Messier objects. So the visibility in your location is the most important in deciding what telescope to buy. | ||
Current revision as of 15:55, 18 March 2009
It is the rule, that a reflector with the same aperture, always costs less than a refractor. This is true also concerning the cheapest telescopes. A 60mm refractor costs almost as much as this telescope, all 70mm refractors are much more expensive. So it is likely the best choice for the cheapest telescope. Refractor is not better than reflector, except some expensive apochromatic refractors, and in a reflector with the same aperture less light would be lost. Some say that the colors seen through the refractor seem "softer" or such, but the difference can only be very small, and also reflector shows the colors as they are, but an achromatic refractor has some chromatic aberration, so that the yellow stars may seem reddish, you cannot exactly see the natural color. The secondary mirror obstruction for this telescope is only 7% by area, which means that this telescope has a 70mm "clear aperture". The biggest advantage of refractors seems to be that they almost don't need any maintenance, and they are also almost eternal, while the reflector's mirror would corrode after 30 or so years. But the maintenance like collimation of the reflector telescope is not difficult at all, and is some fun also, so being maintenance-free may be important only for these who know nothing about any technical things, I would not agree to have more than 10mm less aperture for that reason, and it is not so extremely important for me that a cheap telescope would be inherited by my grandson.
Using binoculars instead of a telescope is another option. I wouldn't say that it is a bad advice to use binoculars, though in the conditions of light polluted skies one likely cannot see much with binoculars either. I don't have binoculars so I cannot compare, but telescope enables to see things much larger, which is important, as the objects like planets look very small even through telescope eyepiece and this makes it much easier to see any details. Using binoculars may be convenient, but would not give an experience of using a telescope. Almost all telescopes have quite narrow field of view, and it is important to learn how to find objects with instruments like these. Thus it can be said that binoculars are just a different kind of instrument, it doesn't make so much sense to discuss what of these is better, telescope and binoculars are just different kind of instruments, both giving a different experience. I think these who want a classical experience of using telescope, should buy telescope. Even better may be to have both.
If you can waste more than $100 for a telescope, consider more powerful pure Newton reflectors, such as the 6 inch Orion SkyQuest XT6 [1]. The XT6 weighs already 16 kg, maybe you may also consider a 8 inch telescope, but carrying a telescope bigger than that would be more like carrying furniture, a big undertaking, which you would not do just to quickly check something, and therefore such telescope would be much less useful. I have found only one similar telescope which should be available in Europe, the 6 inch Sky-Watcher Dobsonian [2], there is also a similar 8 inch telescope. An 8 inch telescope would enable you to see some 2 magnitudes more than this telescope, in all conditions, and 2 magnitudes more makes a lot of difference. Thus if you have to decide what telescope to buy, maybe start from determining the visual magnitude limit in your location, ie determine what is the magnitude of the faintest stars which you see with the naked eye. As much as I can tell, this telescope in the location with good visibility should be almost equivalent to 8 inch telescope in my location, and thus would likely show clearly most of the Messier objects. So the visibility in your location is the most important in deciding what telescope to buy.
