I'd like to buy a telescope with a focal length of 700mm and an aperture of 60mm.
Would I be able to use a telescope of this power to study the closer planets (for example Mars and Venus) and nebulae?
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$\begingroup$ Mars, venus and stars in orion (perhaps you mean the orion nebula) can be seen with the unaided eye - no telescope is needed, so could you refine your question. $\endgroup$– Dr ChuckJan 2, 2019 at 15:19
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$\begingroup$ You also might want to include your location and estimate the light pollution where you're likely to be observing from (i.e. are you in a large built-up area with lots of street lighting nearby?) $\endgroup$– user20278Jan 2, 2019 at 15:48
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$\begingroup$ @DrChuck That's a pretty literal-minded comment. Of course Mars is visible with the naked eye. OP is almost certainly interested in seeing more than the unaided eye can see. $\endgroup$– Florin AndreiJan 2, 2019 at 19:17
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3 Answers
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All the magnifications listed above 84x will be useless on a 60mm telescope.
Still, such a telescope can be useful if it is well made (particularly a steady tripod/mount) and you have reasonable expectations.
It will show lots of detail on the moon. You will be able to see the phases of Venus and Mercury (which is pretty much all anyone can see of those from Earth). You will be able to see Mars as a disk and maybe glimpse an ice cap or a little surface detail under excellent seeing with a favorable apparition. You will be able to see Saturn's rings and Jupiter's moons and maybe with good conditions a band or two on Jupiter.
It will only show a few of the very brightest nebulae, and only as a faint smudge.
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$\begingroup$ Mars is going to be very tough in only 60mm of aperture. It's going to be very rare that any surface features will be visible, if ever. Jupiter's equatorial belts, however, will be much easier. I see them all the time in my 50mm finderscopes. I agree with everything else. $\endgroup$ Jan 2, 2019 at 19:16
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$\begingroup$ Mecan build my own telescope so what material i need $\endgroup$ Jan 3, 2019 at 4:51
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In my opinion, 75mm is the minimal requirement to say that device belongs to "telescope" class.
Magnification itself is useless. For every doubling of magnification you pay with dividing luminosity of your image by 4.
Also check out this black list of telescopes ref.2. All of these have defects which you, as beginner, will have real pain to cope with. As you can see, many of those telescopes are from serious firms. It means that even those are buying cheap parts and save their expenses when producing.
From lower end of telescopes (of refractors), which I consider less or equal of 90mm, I think that most beginners should choose between computerized versus non-computerized model. If you pay for computerized model, you will loose significantly in optical quality of your scope. Example of such choice: Meade Polaris 90 VERSUS Celestron NexStar 90 GT. The most "bang for the buck" choices, from trusted makers. (I do not advise in favor of any manufacturer! If you fall deeply into astronomy, build your own telescope!)
Don't fall for chineese ultra-low-end scopes. You cannot check their optics by web.
PS. If you are strongly on budget, I would even advise to NOT buy any telescope. Make your own. Buy 200mm mirror from trusted source (approx 100-200 bucks) and work your way to telescope by yourself and garage tools (such telescope costs over 500 bucks in stores). Check out ref.1.
PS2. For the planets, your choice of telescope falls more into category of large focal ratio. F/10 works good. Downside is that nebulae are large and could not fit into such narrow angles. Upside is that telescopes with F/10 are moderate at cost. Parabolic mirror could be swapped with spheric and so on. Another downside is bigger weight, because of longer tube (newtonian and galilelian telescopes). Modern schemes like Maksutov/Schmidt-Cassegrains are somewhat "more universal", combining good elimination of spheric aberration with wide angle. But weight is very large. Only buy with EQ5 and EQ6. Or with custom computerized mount.
At last. Best telescope is the one which is looked through everynight. Best telescope manufacturer is your own hands.
References. [1] Number one site for ATM https://stellafane.org/tm/atm/ [2] Black list of telescopes http://www.star-hunter.ru/en/black-list/
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Have you ever looked through a telescope of that size? Astronomy is a hobby enjoyed worldwide. There are astronomical clubs just about everywhere there are people. I would suggest joining a club nearby and getting familiar with the hobby before buying anything.
Electronics has found it's way into Astronomical viewing in recent years. What was no more than a faint smudge in an eyepiece is now clearly visible with modest equipment. Find out what others are doing before making any decisions.
As already said the best telescope is the one which is looked through every night. The only way to determine what is best for you is to look through a few telescopes first then think about what sort of equipment will make you want to use it whenever the skies are clear.
