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Wednesday 25 September 2013

Why to have Celestron NexStar 8SE without watching this video first. 8 inches vs.5 inches

After seeing this video in which are presented the reasons for which an 5-inch Newtonian telescope is better than a larger, like 8-inch, I must not be agree with this opinion.

 He says in the video description that:

 "The main advantage of an 8 inch telescope over a 5 inch one is when you take long exposure photographs. The NexStar mount isn't good enough for exposures longer than around 30 seconds. The planets and the Moon will look the same in both telescopes unless you live in the desert away from city lights. Otherwise the maximum power is less than 300 due to the sky conditions and both telescopes can give you that."

...and,

"Polar alignment is often needed for astrophotography. The NexStar 5SE has a built in wedge in the tripod which allows you to easily align the 5SE with the Earth's axis of rotation. The 8SE does not have this option. If you want to make a time-lapse movie of Jupiter spinning around on it's axis the 5SE is the better telescope. This video goes into more detail."

 The statement that "the planets and the Moon will look the same in both telescopes" is a nonsense. Even with medium 8 " reflector gives a lot more detail on the planet than a 5". The conditions better that of average conditions, the difference is much higher.

I agree with him in saying that with a telescope 8 "you could get 480x and with a 5" one you have 300x and most people observe planets at 200x or less because of sky conditions. But still, the more bigger the more better! All larger telescopes will do is to have more light. More light means more detail. Observation with an 8 " is nice because images looks brighter throughout the zoom range! Image of a 5" will be lower regardless of magnifying power.

There is no reason for saying in video, that if you take an 8-inch telescope you will need a bag to carry, and it cost $ 300 and the bag of a 5" costs $ 140, and for nothing he says a 5" is more easily carried and therefore will be used more often. Who loves astronomy will carry it anywhere and anytime will be pleased to observe through it. It is true that there are those who are not serious with this hobby and will only look at the planets once and then they will sell or it will keep in the closet, but that does not justify anything that a smaller telescope is better than a bigger one. What is the big problem if it is bigger? Telescope tube is the most weightless component of a telescope compared to tripods or counter weights. Only it is larger, otherwise, no big difference.

   And do not forget, especially if you think about the astrophotography, that what it says you to do in this video, it would not be ideal. For dark objects such as nebulae you need to open the shutter for a few minutes and 5SE mount is not accurate enough for this.




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