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| 11/22 |
| 2005/9/12-13 [Science/Space] UID:39629 Activity:moderate |
9/11 Hi John, I was the one who asked for recommendation for an entry-
level telescope below. I liked your suggestion of getting one
that has a motor with usb controller port. It will probably go
way above my budget, but what the heck--can you email me the
make and model of the one you have? I'd also like to see what
your Russian friend recommends. Thx. -tien
\_ Sent.
\_ just be warned. Even with the biggest telescope you can afford,
you really can't see much. At best, you can barely make out
Saturn's ring on a good day, or barely make out the ice caps on
mars. Everything else is just a dot in the sky. Unless you are
really into it, you are not going to find telescope very
helpful - semi-astro geek too
\- are the cheep russian/chinese models worth it unless you are
buying pretty large ones? an associate of mine got a couple
of "communist telescopes" but they are like 6ft long and
i am sure are thousands of dollars. also can you really see
much from the sf bay area?
\_ My colleague just wrote a reply to tien--apparently it was
my mistake, the TAL scopes aren't entry-level, but rather
more affordable if you're up for higher-end optics. The full
text is in ~john/scope
\_ There is a major research telescope in the sf bay area, so
yes. But you need to get up in the hills and away from
lights. -tom
\- well i mean from your homebase. i mean there is a
major research telescope in LA too ...
\_ Do you mean the Lick Observatory? I went there on a
company outing. The only reason they can see anything is
because SJ has had a policy of sodium lamps (so that line
is lost, but the rest of the spectrum was clean).
Unfortunately, the city isn't paying as much attention to
that anymore.
\- there is also a small telescope south of gilroy
on freemont pk.
\_ Saturn's rings are reasonably visible in my 90mm scope, even
from light-polluted Berkeley. I even once managed to spot
the Eskimo Nebula (but it was a tiny faint gray blob that
only showed up in averted vision). But yeah, ice caps on
Mars are hard to see. Don't expect to see vividly colored
nebula as pictured in ads; they're all gray. Until you
buy a CCD and do RGB exposures. -geordan
\_ Have you tried viewing from Anthony Chabot Park?
\_ Not yet, although I did notice that the sky was pretty
bright when observing the Leonids some months back.
-geordan
\_ ObDobson: http://members.aol.com/sfsidewalk/intro.htm
\_ Dobsonian
\_ The person's name was Dobson. Cf. beam in your own eye
\_ The person's name is Dobson. Cf. beam in your own eye
before pointing out mote in another's. |
| 11/22 |
|
| members.aol.com/sfsidewalk/intro.htm Yes, it "looks like a cannon," but the above is really a ten-inch (measur ed by the diameter of the objective) Newtonian telescope that almost any body can build. Here you will find plans to build this telescope, or a s maller one--either a six-inch, or an eight-inch--of identical design. I have kept as close to this design as possible: One, because this is--hands down--the cheapest and easiest way to make a quality telescop e; and two, because I walk in the shadow of John Dobson, who invented ma ny of these designs which have revolutionized amateur and professional a stronomy alike... Besides, Los Angeles Sidewalk Astronomer, Pam Reid, di d most of the work by writing and typing the procedures, as well as gath ering the drawings--which, by the way, were done by Earl Jungians (from photographs of John at work by Molly Lusignan). Most of my "work" consis ted of scanning and re-typing Pam's work... Here you will find the original plans --images and text scanned together, without my minor meddling--which inc ludes, by the way: the Six-inch plans, the Sun Telescope construction ti ps page, a Links page, and a real person to E-mail your questions to. R egardless, it is a beautiful page, and I recommend you check it out; esp ecially if you have any problems printing the plans from this page. gif (77937 bytes) Introduction The plans you will find on these pages, are, by and large, the result of years of trial and error on the part of John Dobson, one of the founders of The San Francisco Sidewalk Astronomers and a prolific telescope ma ker. John has, quite literally, helped thousands of people make telescop es of this design! Only in the past few years have commercial telescope manufacturers adopted the Dobsonian approach to make affordable, alt-azi muth Newtonian telescopes... However, the three top manufacturers (hence forth referred to as: "The Big Three"), Celestron, Meade, and Orion, con tinue to fall short mechanically of the simple designs found on these pa ges. a kind of coated p article board, which is heavy, not durable, in short; not as strong or l ight as plywood, which, of course, we recommend. you might well peruse thes e pages to find ways to tinker and fix up your mass-produced Dob: you ca n only improve what you got! The designs you find on these pages are also open to improvement by you: the builder. Not only will you discover the ins and outs of Newtonian / Dobsonian telescope design, but you are encouraged to come up with your own modifications. We include plans to make your own Primary Mirror Cell (we call it a "Tailgate"), Secondary Diagonal Mirror Holder and "Spider ," and Eyepiece Holder/Focuser. These are items even the most seasoned T M (telescope-maker) usually buys from small telescope part manufacturers : you may opt to do the same (although John's designs are perfectly func tional--some ingenious--and very inexpensive to fabricate). Contact your local astronomy club, there are usually at least a handful of TM's that can help you out. Sources page for materials and acce ssories you will need, or, might want, to purchase. I think you will find these plans pretty clear, simple, and straightforwa rd. |