Be smart when shopping for telescopes
If you've got a stargazing fan on your holiday gift-giving list and you're considering a telescope for that special someone, even if that someone is you, I want you to buy right and buy smart. Get the most astronomical bang for your buck.
The most important thing a telescope can do for you is gather light. That will determine how clear the astronomical target will be.
Light gathering ability is determined by the aperture of the telescope. The wider it is, the more light you're able to gather.
Magnification is clearly in second place to light gathering ability. Too many folks go for scopes that brag of high magnification without considering aperture, and that's too bad because you could wind up with a scope that gives fuzzy disappointing views, and what good is that?
Beware of telescopes that claim something like 500 or 600 magnification power. That's just asking for trouble.
Even though you'll see astronomical targets over 500 times larger than you would with your unaided eyes, there's a very good chance that all you'll wind up with is a mess of fuzz and a lot of disappointment.
It's been my experience that many telescopes that claim outrageous magnifications are found at online shopping websites. I really think that your best bet is to purchase a telescope from an outlet that specializes in astronomy and telescopes, both online as well as brick and mortar. I'll have some specific recommendations toward the end of this week's column.
Getting back to magnification, most of the time you'll be very happy seeing heavenly bodies in a general range of 100 to 200 power range. In fact, some celestial goodies look their best with less than 100 power.
Magnification depends on what size eyepiece you use with the scope and most telescopes come with several eyepieces to give you a range of magnification power.
I really think you'll enjoy the low-power images through your telescope because even though they're smaller, they are the clearest.
Refracting telescopes
The least expensive way to go with a telescope in most cases is a small refracting telescope. These are the kind of telescopes most people think of when they think of a telescope.
Light is collected by a lens called the objective lens in the front of the scope and is bent toward the eyepiece at the rear. The wider that objective lens is the more light gathering you'll have. The minimum diameter for the objective lens should be about 60mm. Anything less than that and you have a toy.
Refracting telescopes are sold by the width of their objective lens. A 60 mm refractor has a 60 mm objective lens. A 90 mm refractor has 90 mm objective lens, and so on.
The minimum you'll have to spend for a decent refractor telescope will be about $200 to $300. Anything less than that just isn't worth the money if you really want to give a gift that'll be truly appreciated and used.
Newtonian reflectors
My favorite telescopes are Newtonian Reflectors invented by none other than Isaac Newton in the 17th century. You'll have to spend a little more money, but I think they're so worth it.
They collect light from celestial objects with a concave parabolic mirror in the rear of an open tube. The collected light bounces back to a focal point at the front of the tube and is directed by a secondary flat mirror to the eyepiece mounted on the side of the tube. Just as it is with any telescope, different eyepieces give you higher or lower magnification.
The easiest reflectors to use are the ones with Dobsonian mounts. They're often referred to as “Dobsonians” The minimum size reflector you should get in my opinion is one with an eight-inch diameter mirror, otherwise known as a eight-inch reflector scope.You can get one of those on the Web for about $400 to $500.If you're looking to get a first telescope for a really young child from about 6 to 10 years old, I have a very specific Dobsonian telescope recommendation. It's the Meade telescope Lightbridge Mini 82 with an 82 mm mirror. It's so easy to use as it can sit on a tabletop. You can get nice views of the moon, planets and more. Depending on where you buy it you'll be spending about $60 to $70.If you have an older “giftee” you can really do it right with a computer-guided Dobsonian reflector. I think the best buy out there is from Orion Telescopes. I'd highly recommend the Skyquest XT8 Intelliscope Dobsonian telescope that comes with multiple eyepieces and a computerized object locator that can be a huge aid in helping you find astronomical objects.It's priced at around $700 but I think it's well worth the money. You can find out more about it on the Orion Telescope website.For even more money you can purchase reflectors with even larger mirrors and you can even buy telescopes that'll actually point to any object you choose to view from a computer library of thousands of objects. Get your wallet ready for some of those.Cassegrain telescopesCassegrain telescopes are another kind of telescope that are more or less a hybrid of reflector and refractor telescopes. They're generally much more expensive but are fairly portable and do a great job. They all have the capability to physically direct the scope to any astronomical object you can dream of in the night sky and keep it in view with motors than compensate for the Earth's rotation.One of the hassles with these “go to” telescopes is they have to be aligned every time you use them. If you do it right it usually only takes a few moments but now with an additional accessory you can hook up to Celestron Brand Cassegrain scopes. It's called Star Sense. Just enter in the date and time and Star Sense will align the scope for you. I bought one this past year and love it.An important rule to remember with any telescope that you want to pass on to whoever you're buying the telescope for is to let the scope sit outside a good half-hour before you use it. That lets all the lenses and mirrors stabilize so you get a clearer image. Never poke your telescope out of an open window. The heat currents coming from your house are surely going to mess up the image.
As far as astrophotography with a telescope, it's not an easy process and certainly not cheap. That's actually a column for another day.I will say this, though. At least for bright objects, especially the moon and the planets, it's amazing what you can do with a cell phone camera.There are even mounting devices that'll latch your phone on the eyepiece of your scope but just holding the phone over the eyepiece can produce some amazing images.There are many good brick and mortar astronomy/telescope retailers across the U.S. and I'm lucky enough to have a great one in the Twin Cities. It's Radio City Astronomy in Mounds View, Minn. Its website is radioinc.comThere are others, but there are two main websites I recommend for online purchases: Telescope.com for Orion telescopes and Telescopes.com for brands like Celestron, Meade, and others.I'm also a big fan of Starizona.com, which also has a wonderful store in Tuscon, Ariz. If you ever have a chance, check it out. The people there are so informative and very nice on top of that.Make the stars your old friendsIf you have any astronomical questions or want me to write about something you're seeing in the night sky, drop me a line at mikewlynch@comcast.net<em>Mike Lynch is a professional broadcast meteorologist for WCCO Radio in Minneapolis/St. Paul and is author of the book, “Stars: a Month by Month Tour of the Constellations” published by Adventure Publications and available at bookstores or at http://www.adventurepublications.net</em>
