I have a Meade DS-2080AT-LNT. It's an inexpensive scope that I've had for several years. It has a couple of eyepieces with it, but nothing that will let you get a really good look at planets. I doubt I can see any Messier objects as more than a blip.

But it's more than good enough to take up and leave at my family's cabin in the far North and I think all of the kids that visit will enjoy it. But to get more out of the scope I was thinking about getting a Barlow lens. I see lenses of 2x and even 5x for sale. I don't know enough about telescopes to know what "x" of Barlow I should get for this scope.

The specs are as follows:

  • 80mm (3.1") Aperture: Plenty of brightness to reveal planets, clusters, nebulas and more.
  • Sturdy Fork Mount: Lightweight and solid aluminum mount and tripod for stable views.
  • 494 AutoStar® Controller: Automatically locates more than 1400 objects and points the telescope toward them for you at the push of a button.
  • Series 4000 Super Plössl 1.25" Eyepieces: (26mm and 9.7mm) Enjoy low and high power viewing with crisp, wide fields of view.
  • Altazimuth Set-up: Easy-to-use mount moves up/down, left/right.
  • SmartFinder™/Red Dot Viewfinder™: Makes stars and other objects easy to find. Electronic level sensor, north sensor, and precision internal clock help get your scope aligned with the heavens quickly.
  • AutoStar Suite™ DVD: Amazing planetarium software and instructional video will help you learn about the night sky and how to use your telescope. Print out star charts. Plan observing sessions. Displays over 10,000 night sky objects. Operates on any Windows®-based PC

I appreciate any help!


1 Answer 1


The magnification is given by (focal length of telescope)/(focal length of eyepiece). The spec I saw said the telescope focal length is 800mm, and the maximum magnification is 160x, so to get that would need a 5mm eyepiece.

Barlow lenses have the effect of increasing the telescope focal length: the 2x barlow would therefore give an effective focal length of 1600mm, and using the 9.7 mm eyepiece would give magnification of 160 (approx). However be aware that the occasions when 160 magnification gives really clear views will be quite rare, as it is at the limit of what an 80mm scope can achieve. The rule of thumb for maximum useful magnification for a good scope is 50x the diameter of the objective lens (in inches).

  • 1
    $\begingroup$ MInor nit: replace "maximum mag" with "maximum useful mag." And of course there's the addition of adaptive optic primaries, but that's a different cost level. $\endgroup$ Mar 28, 2018 at 15:44
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    $\begingroup$ @Carl - comment about useful magnification adopted. $\endgroup$
    – Dr Chuck
    Mar 28, 2018 at 23:13

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