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Maximum Useful Magnification

Need our opinion on a telescope Optics Planet has on sale, go ahead and ask! Post some hints and tips on various telescope brands and configuration.

Maximum Useful Magnification

Postby MM on Sun Jan 04, 2009 11:28 am

I am investigating purchasing my first telescope, wanting portability, and am looking at the Meade ETX 90PE. I noticed in reviewing your site that you mention several times aperature, not power of magnification, should be a checklist item when considering a telescope. I saw in the spec sheet for this telescope that the maximum useful magnification is 250x. I also read in backyard skywatching books that the maximum power any telescope can deliver is 50 x the aperature in inches; exceed this limit and the picture gets fuzzy and faint. If that statement is true, then 50x3.5=175. What am I not understanding here? How is this telescope able to overcome the range of 175-250?

Postby Ryan_W on Tue Jan 06, 2009 4:53 pm


There are many other factors than just the aperture that affect the maximum power that a scope can handle. The most important factor is the atmosphere. It is very rare that you will get a clear and still enough day to observe at 200x or higher and still have a good image. 175x to 200x is a good area to atay at or below with your scope.
Best regards,

Ryan W.


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