what is the overall best portable telescope for planetery viewing?

One Response to “what is the overall best portable telescope for planetery viewing?”

1. n2s.astronomy Says:
   July 13th, 2010 at 10:02 pm

   The answer would depend on your budget, and your definition of the word "portable". For some, a 30 inch Obsession fits the ticket,

   http://www.obsessiontelescopes.com/telescopes/30/index.html

   or you can spend that much or more on a high grade apo refractor.

   http://www.skiesunlimited.net/product.php?ProductID=4222&CategoryID=313

   Most of us are happy with a far more modest instrument on a scale that can be easily managed.

   During the 19th century, amateur astronomers would have been happy with your 60mm telescope. The average telescope in their hands would have been a 3-4 inch refractor, and it would have been expensive.

   See chapter 1 here:
   http://books.google.com/books?id=DDcDAAAAQAAJ&dq=book+%22celestial+objects%22&pg=PP1&ots=FS9gBsUl2H&source=citation&sig=ZF-eWLT2FNDSC41bXOIp4bQdEgs&hl=en&prev=http://www.google.com/search%3Fhl%3Den%26q%3Dbook%2B%2522celestial%2Bobjects%2522%2B&sa=X&oi=print&ct=result&cd=1&cad=bottom-3results#PPA1,M1

   I can sit here and recommend all kinds of equipment for you, but it would be pretty meaningless. I have used many 60mm scopes, and they can and do often provide a decent view of the moon, and the brighter planets; and, it is a very inexpensive solution that can be picked up with one hand and tossed anywhere. Just keep the magnification under 120x and these scopes will give you a resonably sharp resolution. Your box may have proclaimed some other ridiculous number, but keeping it at or under 120x will help you to comply with the laws of physics. (note: the barlow supplied with these scopes is usually worthless, and the whole can be greatly improved by buying a 1" to 1-1/4" diagonal along with a couple of 1-1/4" format eyepieces – like a 25mm and a 10mm)

   Upgrading to a 90mm-120mm refractor on an equitorial mount will give you much nicer views of the same objects at around 200x. Which is as high as you would probably want to go until you can add a decent clock drive. At that magnification objects will drift through your field of view fairly quickly. The equitorial mount will help you to stay on target; when it is correctly set up, you will only have to move your right ascention control to keep it locked on target. For planetary viewing, the EQ mount is a big plus. The big dobs light buckets are excellent for widefield DSOs, but tracking a planet under high magnifiction can get old – although, some dobs can be equipped with clock drives and tracking systems and these will work fine.

   Each instrument has its own advantages and challenges, and much of it depends on your personal preference. The refractors will get expensive and long with larger apetures, and looking at objects near the zenth will often position the eyepiece uncomfortably low to the ground. The reflectors are much less expensive, especially when mounted on a dobs mount, the optics will require more frequent collimation, and the bulkier tubes are more subseptable to wind and temperature variations. The SCTs are a nice compromise between the two and can offer long focal length and resolution in a compact and comfortable package.

   Find a local astronomy club and make it a point to try a variety of these scopes. You might even decide to go with a nice pair of binoculars. The important thing is to go out into the night and look up to take in that big celestial show.