Question
Stupid and nonsense. Don’t try to spread bad information. You are always not correct about any of your information in this thread. Maybe you like to start an terrible discussion here ? Go ahead.
Anwser
So, I listen this advice and go ahead! He did meant, that my explanations concerning possibility to have a 98% reflectivity on the telescope mirrors with Ag+SiO were wrong, of course, due to my stupidity. For thouse, who don’t know the subject, I briefly explain what is the matter of discussion. In all mirror type scopes their mirrors, as a rule, coated by thin aluminium lyer which has around 90% reflectivity – it is difficult to say this % exactly, because all depends from coating pro- cess, haw clear the aluminium to be dispersed, haw old the coating is. With intention to increase the reflectivity of the aluminium, scientsts has developed a special technical proceses where many(up to 38!) very special dielectric materials dispersed in a very very thin lyers above alumi- nium lyer. Due to interference of the light in these lyers it were possible to increase the total reflectivity up to 98%. The dielectric material are specially choosed in their refractive indexes, the thickness of each lyer is also under special control. This technic is not very simple and, of course, is not cheap . There are some different dielectric coatings which brings different percentage of the reflectivity. There are no any another ways to increase the reflectivity of the aluminium lyer (as well as any another metal) . ALL high reflective overcoatings are based on the interference of the light in these dielectric lyers and on the behavior of the electro-magnetic waves on the boundary of two media (lyers) – the Maxwell theory. What our connoisseur do offer to solve this problem? Simply to cover the mirror by the silver( Ag ) lyer + quartz oxide ( SiO) overcoating ! Not more and not less ! That mean, that all numerouse optical firms and research institutes were slept and missed such simple and cheap way out! It is a well known fact, that silver has a better reflectivity than aluminium in the visible light range ( and much worse in violet-ultraviolet) . But silver is much less durable against agressive enviroment than aluminium and so, for a long time use, the silver lyer sholud be protected by durable lyer of quartz oxide (SiO) . But this SiO lyer can’t be very thin, owtherwise it will not work as a protection lyer. This thick enough lyer will work like simple thin glass and will cause around 8% energy loss. Of course, such Ag +SiO coating will win in the visual spectral range against Al + SiO coating. But in any case we can’t speak about 98% reflection on such mirrors. If someone here is a physicist and also is an expert in the coating field , he can correct me if I am wrong.. I can add also that we have a equipment for the SiO and SiO2 over- coating and I am practically familiar with a basis of this process. About using quartz as a substrate for meniscus manufacturing. Our famouse connoisseur claimed, that it is not a problem for him to opbtain the quartz with a very high internal homogeneity for a very resonable price if not for a very cheap price. Note, please, he speak that this quartz will be quite suitable for the manufacturing of the front meniscus lens in the scopes with a total wave front error in around 1/10 wave! That mean, he is able to use for his new Maksutov telescopes (up to 12.5″ ) such unique quartz . Uhhhh! So nice luck! But….. I can responsibly say that in the former Soviet Union all attempts to develop reliable technology of manufacturing of large enough quartz blanks with a highest internal homogeneity were failed. And only relatively recently few western optical firms reach a success here. But even not worth to speak about using such quartz as the substrate for the meniscus in an amateur Maksutov scopes – the price for this quartz is too high. So, amateurs!, aware to buy any scope with a quartz meniscus unless you know that this meniscus was really made from quartz and the scope has a reliable certificate of the quality. Even in this case it will be better to check-out this scope personally before the purchase. It is very easy to make a hype with intention to draw an attention to his own person and possible(!) products, but much more difficult to make this real. Even if nothing promised will be done, the minimal task – to draw an attention – was sucessfully reached.

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Question
I am planning on buying a telescope. I have heard that the Reflector scopes sre better than Refractors, is this correct. or is personal preference?
Anwser
Not really. The reflector, gives more aperture/buck, and by default, does not suffer from chromatic abberation, but instead gives either coma, or spherical abberation (or a combination of both), with in the more normal designs, diffraction from the central obstruction as well…. It is the better buy for a budget. They can also be built larger more easily. The simple Newtonian reflector, gives the best views for a given price, and it is far better to buy (say) a 6″ reflector of this sort, than to spend the same sort of money for a 2″ refractor… However really carefully designed refractors will give better images than a reflector of the same size, but to do this, will be built using lenses with a combination of different glasses (flourite in the most expensive designs), to reduce the chromatic abberation to allmost nothing. However designs like this start at perhaps $2000 for even a small 4″ scope…
Associated Bushnell Reflector Telescope Question: I have checked – Meades – Galileo – and Bushnell web sites. and came up with the following: 1.Meades DS 2114 Reflecting Telescope with Autostar Computer Controller—- 114mm mirror – focal length 1000mm ( F/8.8 focal ratio)- 3 optical eyepieces- SR4mm, H12.5, and H25mm , – 5×24mm –3xBarlow lens –finderscope – remote control -Autostar hand controller for built-in motor drive,– Altazimuth Mount – Adjustable Tripod w/tray. Starfinder Software – and Bonus electronic eyepiece. Mfrs $600 One place has $399 another $229 for the exact same model. 2. Galileo 5″ Reflector Telescope — 130mm mirror– 2 eye pieces 6mm and 20mm,(1.25 format )–3x Barlow lens–Equatorial mount–rack and pinion focusing. Tripod w/tray and software. This is on HSN $249 sells for MFRS $565 3. Galileo 1000mm x 4.7″ Reflector Telescope– eye pieces (25mm, 6.8 to 16mm zoom -63x to 147x, 1.5 erecting eyepiece, 3x barlow lens–Mars eye finderscope–rack and pinion focusing–super glide mount w/ slow motion control–double center weight,–Tripod/tray/and software. HSN $139 4. Galileo 900mm Reflector Telescope w/ 4.5″ mirror–30mm Marseye finderscope- LED Red=Day, Green=night–3 eyepieces 6mm,20mm and 1.25″–3xbarlow lens–equitorial mount–split counter weight–rack abd pinion focusing–microaltitude adjuster–flex cables==solar aperature cap–Tripod / tray /software. Mfrs 499 $172.50 5. Bushnell 675 x 5″ Reflecting Telescope w/equitorial mount– Motorized–2 eyepieces 6mm, 20mm 3 x barlow lens–Red dot finderscope–Tripod tray and software. Mfrs $379 QVC 189 Also is the new Galileo Video Accessory Pack Worth getting? — which is high-resoultion video camera that attaches to the scope with an adapter and then sends images to the 5″ monitor (included) or to a TV set. comes w/ video cord, DC car adapter, AC to DC adapter and carrying case Mfrs $199 HSN $99. Thank you in advance for your help.

• Anwser:I’d suggest starting again, and reading the following sites first: http://www.perkins-observatory.org/FAQ.index.html http://members.aol.com/bemusabord/first.html http://www.airdigital.com/article_buyingscope.html http://www.bentilean.freeserve.co.uk/telescp6.htm http://www.findascope.com/ All the models you have looked at, fall rather into the class that is normally referred to as ‘department store’ scopes. These are designed to ‘look good’, and not necessarily actually perform terribly well. Though the Galileo has a EQ mount, it is terribly light for the scope involved. Forget Bushnell. The Meade model is reasonable, but you are spending money on the gadgets, rather than the scope. Have a look instead at something like the Orion SkyQuest XT6. This will beat all the scopes you mention, by a very good margin… Forget about the video accessory pack. A good telescope CCD, will start at perhaps $1000, and these cheap units, are basically just standard TV cameras, built into an eyepiece case, and are only worth using on bright objects, that you could see better through the eyepiece!. They can be useful if you want to show things to several people, but otherwise are a gimmick!. Something like the SkyQuest, can be set up really quickly, and is portable enough that you can go to sites with less light pollution. Used like this, it can give views far better than many of the astronomy ‘pioneers’ had. Best Wishes
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Question
should I buy the mirror ready to fit for a first build or start from scratch?
Anwser
I built a 10″ Dobsonian a couple of years ago and it’s good fun. I bought a complete mirror set from Orion Optics which was where most of the money was spent (£365) but I also treated myself to a right angle finder (Orion £96) and a low profile Crayford style focuser (Moonlight Telescope Accessories $165). Total cost including the plywood and cardboard tube was probably in the region of £600 but I could’ve spent less overall if I’d tried harder. I’ve read up on mirror making and quite fancy having a go. I’ve recently purchase “The Dobsonian Telescope: A Practical Manual for Building Large Aperture Telescopes” written by David Kriege and Richard Berry. I’m looking into finding a 20″ mirror blank at the moment. The way I see it is that I’ll never be able to justify thousands of pounds of a Meade/Celestron etc or even thousands on a finished large mirror so the only option I’ve got is to grind/polish my own. Although I’m sure there are people that will say “start with something smaller”, from what I’ve read you need time and patience to make a good mirror not really amazing talent. It may take me longer to make the mirror and it may not turn out as good as one made by a professional optician but it’ll be cheaper and I’ve no doubt it will yield good views so long as I’m careful and take my time. So it really depends on how confident you feel and how much workspace, time you have versus how much money you have to spend on optics. For example I could but a 500mm primary for the bargain price of £1730 or I could give my own a go and spend between £320 – £540 (depending on glass used in the blank) plus the time taken to make it. Obviously after it’s been ground and polished I’d have to get it coated but that’s about £100. It’s still half the price of a ready made one. Anyway here are some URL’s that may help. http://www.galvoptics.fsnet.co.uk/ click product/telescope mirrors. They do kits, blanks and finished mirrors. http://www.beaconhilltelescopes.mcmail.com/ also do blanks (though not as big), kits and finished mirrors. http://www.greenwich-observatory.co.uk/ various stuff but the only place I found the Kriege/Berry book available in the UK. This book although is all about large truss style Dobs has an appendix about mirror making and is a very good source of building info/tips. http://www.orionoptics.co.uk/ various stuff again and very good quality finished mirrors if you want to go that route (only upto 350mm though). http://www.focuser.com/ USA supplier of low profile focusers. And some ATM sites I’ve found good info from. http://www.astrosurf.com/jwisn/20inch.htm http://www4.tpgi.com.au/users/daveg/index.html http://pong.telerama.com/~mdholm/atm/cells/ http://members.shaw.ca/fvas2/index.htm very good stuff on the “how to” of mirror making/testing etc. http://www.newportglass.com http://pages.infinit.net/asmprod/ just had a quote for a 20″ mirror blank plus shipping from Canada from these guys.
Associated Orion Dobsonian Telescope Question: Recently an Orion telescope catalog arrived in my mail box. I have been looking on and off at telescopes and Orion seems to have the best prices for what you get. Not having seen one up close I was wondering if they make a good product. My son has a brand name telescope that was expensive and is a POS. The ones in this catalog look better, have better specs, and are way less expensive. But I’m sure someone in this great newsgroup knows for sure about their quality. Thank You, Eric R Snow, Trying not to get ripped off

• Anwser:I have an Orion 90 AZ (refractor) http://www.telescope.com/shopping/product/detailmain.jsp?itemID=294&i…. Got it for the children a few Christmases ago. I shopped around quite a bit locally before I bought it. It was a great deal better quality than telescopes from Meade or Celestron of similar type, and specs. And it was cheaper to boot. Pretty decent quality. This one was made in China, some of their better scopes are made in Japan. Had a lot of fun with it. Unfortunately, because of the city lights, not too many stars visible around here. Mostly moon gazing, and when I can find them, Jupiter and it’s moons and Saturn with rings. Now the scope is mostly pointed towards the SF Giants scoreboard at PacBell Park.
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Question
It’s one of the largest dozen or so refractors ever. I’ve looked through a 10″ Cooke refractor at Mills Observatory in Scotland… But this is more like 27-28 inches. Next time I have some time in Germany, I’m going to have to get over to Treptow and check this place out!
Anwser
Objective lens diameter was 26.8″: http://tinyurl.com/allbpa What I’m trying to figure out are two things: 1. How do you keep the thing aimed in one precise direction in even the lightest of winds? You would think it would whip all over the place as the tube above the guy wires flexed, particularly given it extremely high f ratio…so that you would never be able to zero in on a star at even low magnification. 2. How do you keep rain, dust, and pigeon poop off of the objective lens given its completely exposed situation? You might peer up the eyepiece someday and see fuzzy images of storks building a nest on the front lens, like they do on the tops of chimneys. This is _no_ way to make a large telescope. It needed a dome over it.
Associated Question:Hello scopers, Does anyone know if Meade is working on a GPS telescope to compete with the Nexstar 11 GPS computerized go-to scope? I am also impressed with the looks of this machine – very well done. The new tool of the future, take it outside – turn it on – and it’s ready to observe. Has anyone seen or used one of these scopes and how does it compare to our LX-200’s?

• Anwser:The NexStar 11 has only just been announced. It’s not expected to get out to the dealers until Feb. The only people that can have possibly seen it or used it are Beta users, if Celestron does such a thing.

Associated Question: Mfr. #1 has a 12 channel receiver embedded in one of the fork mounts. Mfr. #2 has a 16 channel receiver also embedded in a fork mount, and makes the following claim: “Precision GPS Alignment: Telescope alignment is accomplished automatically using integrated true-level and North electronic sensors in combination with a 16-channel GPS receiver located in the left-hand fork arm…… Competing GPS telescopes use a 12-channel receiver (resulting in slower and less reliable position acquisition), do not include any magnetic declination compensation, and can easily result in first-alignment- star errors of up to 20° or more. ” Do I have a marketing-hype sighting here or are there more than 12 usable satellites above the horizon at any one time? No mention is made of receiver configuration(parallel, WAAS, etc). What are the 4 extra channels doing for the user?

• Anwser:I’d say it’s largely marketing hype. It’s rare enough to see 12 satellites high enough above the horizon to be usable. In principle, the acquisition could be a little faster since you can have multiple receivers doing frequency sweeps to look for the same satellite – the more you have looking, the faster you can lock onto the satellite signal and start getting the ephemeris data. But I’d expect the difference to be very small and completely negligible when compared to the setup time for either of these telescopes. Celestron does seem to have a problem with not including magnetic declination effects, but hope they’ll be able to fix that with new software.
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Question
You may want to talk to SRB in Luton http://www.srbfilm.co.uk/index1.html about making a suitable adapter. They make all sorts of odds and ends, but aren’t overly economical They quoted me £40 for a Nikon to 1.25″ lens adapter (for plugging astronomical eyepieces into the lens.
Anwser
You have shown the extent of this Granddad’s ignorance !! I had assumed that a ready-made thing called a “telescope-eyepiece- adapter” was something that got clicked on to the back end of my 400mm Vivitar photo lens and through which I could immediately look, using it as a telescope. Now I have to guess differently: it’s a two-stage operation, in which Part A is to somehow acquire a bit of metal thingummy-wotsit which clicks on to the back end of the 400mm lens and converts that back end into something more similar to the back end of “astronomical telescopes” but I then still have to (Part B) find/acquire the ….. “glasswork” ? OK – the way might be clearer – mebbe ! SUPPOSE that SRB or whoever produce such a piece of metalwork for me what the heck do I *then* have to go looking for in order to compete this conversion operation and give me something I and the grandchildren can actually peer through ??? I assume that this latter part (the “glasswork”) might be more readily available / easier to source ? What would be its name … ummmm, should I guess “eyepiece” ? John the Totally Uninitiated Geriatric
Associated Telescope Vivitar Question: My nephew received a Vivitar 50x/100x telescope for Christmas. It was purchased in a department store for about $20 -$30. I set it up for him but we can’t see anything good. My cheap 7 x 35 binoculars are way, way better. I know some of you might say the telescope is junk but am I doing something wrong? Is this telescope that bad? The moon just looks like a white ball with no crater. With the bincoluars the moon is fantastic. Lots of possible reasons. Generally, at that price, the original manufacturer has pressed together very cheap parts, and many things may have gone wrong. Until you get above the $200 line, binoculars of the same price are likely to be more useful and better quality than a telescope.

• Anwser: I’ll have to disagree with that. There are many decent telescopes priced -well- under $200 that will show more and work better than similarly-priced binoculars. Recognizing them is the trick. I would guess that the eyepieces are the biggest problem with the OP’s scope. A better tripod wouldn’t hurt either.

Associated Telescope Vivitar Question:Hi, Has anybody had experience with the Vivitar 2700, How would you Compare it with the OLY 220 or other 640 X 480 Cameras. I Tried it on the Video(TV) monitor at “Wally World” Colors seemed OK Some jaggies on some banner tops hung from the Ceiling. Fast shot!

• Anwser:I just recently bought a Vivitar 2700 and love it. The image quality isn’t professional-grade, but quite suitable for my needs (mainly personal snapshots and pictures for use on the Web. The software can be a bit flaky, though — you might consider Sandisk’s flashcard reader to transfer the images to a PC. (The reader is still out of my price range for now, especially since the software seems to finally be working right.) A nice feature, especially compared to the Epson model I saw in the store, is the 2700’s full-motion display (not 2 shots per second like the Epson), and the video-out feature. With a video-capture card (NTSC in the US and I’m told PAL format in Europe), you could do videoconferencing or home movies or whatever. Coupled with a portable VCR, you’d have a camcorder as well. Not it’s main selling point, but it’s nice to know it’s there. (Besides, you can have fun taking pictures pointing the camera into the TV monitor…) I use the high-res mode and get 40 shots on the optional 4Meg flashcard and 20 more on the internal memory. I wish there was a way to use less compression — the camera seems to use whatever compression will fit the picture into 96K — as 640*480*24bit would be *very* nice if not for the JPEG compression. Some of that can be cleaned up with smoothing once the picture’s on the PC, but some damage is irreversible. I may use the low-res mode for household inventory shots and such, but that would be about the extent of it. On simple shots, the contrast and color are quite good, though with suboptimal lighting the camera tends to do funny things with color (like turning the light-blue carpet in the house lavender. Go figure.) On complex shots where the 96K is used up on detail, it looks like a typical JPEG shot at IMHO too high a compression rate. I plan on writing a web page on the camera — I’ll put it at http://www.cs.odu.edu/~carr/digicam when it’s done, and some pictures there shortly in the meantime. Battery consumption is a problem unless you use NiMH cells — I’m now using Radio Shack NiMH AA cells and the camera does quite well. (Sorry, I haven’t really timed it systematically as yet, but the cells seem to outlast the memory capacity with no flash if you’re taking pictures fairly quickly.) Turning off the LCD really helps battery life, but it’s a *great* aid in picture composition — I hardly ever use the cheap viewfinder, but it’s there… Low-light performance is a disappointment, but I’ve heard that about a lot of digital cameras, so I don’t know how bad/mediocre/good the 2700 is in comparison. I was concerned about the fixed-focus aspect of the camera, but as it turned out, this wasn’t a problem. It’s done a great job; if you have sufficient light to use the small aperture setting, the camera can focus fairly well literally up to zero distance. I took a picture of the computer monitor and the resolution was close to what the monitor itself was providing (14″ .28 dot pitch SVGA running 640*480*24bit) The picture was of some ASCII characters with the camera actually touching the monitor. It also takes some doing, but I was able to get a decent (not NASA-quality but amazing considering the conditions) shot of the full Moon by shooting through a pair of 12*35 binoculars. (I aligned it by taking the shot after lining up the camera with the binoculars using a bright streetlamp.) I’ll put the final picture on the web site. I’m even working on a design to mount it to my telescope. Yes, I know I’m quite mad. But it’s such fun. Good luck with whatever camera you choose. Hope this helps. I’ll be happy to answer any questions I can about the 2700 via email.
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Question
Thanks to everyone for all of the posts that help me get this far! After reading for days, I have decided to buy a Orion SkyQuest XT4.5 Dobsonian. This is for my family and my 8 year old daughter who has asked for a telescope for over a year now. I also have a 10 and 14 year old who will enjoy it. It was in my $300 budget (with accessories) and the reviews have been pretty good for an entry level scope. The questions I have are: 1. Orion sells a $30 Beginning Stargazer’s Toolkit that I plan to buy that has some star charts and a book. Is there any one other book I should get? 2. The more expensive DOBs (XT6 or XT8) recommend getting a collimator laser alignment gadget for doing collimation. I know the basic idea is to align the mirrors but I need to know if I need a tool to do this with the XT4.5? How often does someone need to do this alignment? And do I need this laser tool to do it correctly. I hesitate to buy a $79 tool for a $200 scope. 3. Will a barlow lens help this scope be much better? 4. I think this scope will see rings on saturn and moons around jupiter which the kids will think are cool. Will this scope see any deep space objects worth seeing? I appreciate any help on the above questions.
Anwser
My first telescope was the XT4.5 and I still have it. I also have an XT10. I think the XT4.5 is a fantastic little dob that can show you many wonderful sights. I will try to answer your questions in turn. 1. Orion sells a $30 Beginning Stargazer’s Toolkit that I plan to buy
Associated Skyquest Telescope Question: 4. I think this scope will see rings on saturn and moons around jupiter which the kids will think are cool. Will this scope see any deep space objects worth seeing?

• Anwser:The first thing I ever saw through a telescope (the XT4.5) was the moon. The next was Saturn. Not only will you see the rings of Saturn, you will see the cassini division and possibly some banding on the planet (on very good nights). 3 or more moons should also be visible. Mars will show you the south polar cap and some nice dark mare features. Jupiter will reveal at least 2 bands and maybe a bit more on very good nights. You will also get to see all 4 moons around Jupiter. For deepsky, Andromeda will be a wonderful sight. Although mostly a smudge, it will be amazing to realize it is another galaxy. The Orion nebula will amaze you and you will easily see 4 stars in the trapezium. Globular clusters will be a nice sight. If your skies are dark, you can go after some of the more popular planetary nebulae. These will be more in the smudge category, but it is remarkable to think what it is that smudge represents. And don’t forget the double stars out there. These went overlooked by me for a long while until I began looking at them. Some of them are truely beautiful. Now, I’m going to do the standard thing and recommend a more expensive telescope, but only by $49. Take a look at the 6″ dob from Hardin: http://www.hardinoptical.com/dsh6.html This is the same telescope as the XT6 prior to the Intelliscope line. A truely fantastic beginner telescope. You will get your money’s worth out of that extra 1.5″ of mirror. Another recommendation I will make is to visit the Skyquest telescope Yahoo group: http://groups.yahoo.com/group/skyquest-telescopes/ There are many experienced and inexperienced folks that are very friendly and helpful. Let us know what you get and please share your families new experiences with us. The most fun I have is when I’m sharing the view with the kids in the neighborhood. Clear skies,
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Question
Can someone out there please tell me what the differences are between the different types of eyepieces? I’ve heard of modified achromatic, plossl (altho Meade has 3000 AND 4000 series here and have seen Sirius Plossl’s from Orion, Naglers (mega $)?????
Anwser
The following is a list of the different types of eyepieces available: Huygenian, Ramsden, Kellner, Plossl, Erfle, Orthoscopic, Lanthanum, Wide-Field (which is a modified Erfle) and Nagler. Each has it’s advantages and disadvantages. The problem is that each manufacturer tends to couple eyepiece “types” with a unique “adjective” to create a “model name”. Or the manufacturer creates a unique name altogether. For example the Modified Achromats by Meade which you asked about are actually Kellners. Unfortunately I think that the discussion describing different eyepiece types and their virtues/fallacies would be too long a post to leave here. There was an excellent article in the June 1993 issue of Astronomy (if you can get a copy), in which descriptions of the eyepiece types were matched to a “catalogue” of what’s available from each manufacturer. Another good source for information would be Terrence Dickinson’s and Alan Dyer’s book “The Backyard Astronomer’s Guide”. I recommend it highly. It is an excellent reference book for anyone who is just starting out with a telescope and a lot of ambition. Included, is information on telescopes, eyepieces, accessories, observing techniques, descriptions of planetary and deep sky objects (as well as recommendations for equipment for viewing each type of object), astrophoto techniques, and some rudimentary star charts to get you started. The only other piece of advise I could give you (and this worked for me very nicely) is to go to your local telescope shop, if you have one close to you, and try out the eyepieces yourself. The store’s owner (where I bought my telescope) was more that happy to let me “borrow” one of his used scopes for an afternoon. I took it outside and had a good look through just about every type of eyepiece he had, in daylight of course. In addition to seeing the different fields of view that each eypiece provides, I was able to assess how “comfortable” each eyepiece was to use. By the way, I too bought a Meade Dobsonian (the 10″ model) but did not go for the eyepiece/finderscope special. Instead I bought a Meade 8.8mm Ultrawide, a 32mm SuperPlossl, and Meade’s excellent #140 Barlow. Along with the cheaper 25mm MA eyepiece that comes with the scope, this makes a nice combination. As far as a Barlow goes, buy the best. The common belief, I think, is to not let the barlow become the weakest “link” in the “chain” of optics that light must pass through in your system. The Meade #140, or the Celestron Ultima 2X would be good choices. There may be others. Generally speaking, stay away from zoom barlows. Their quality is usually not up to par with fixed-magnification barlows. And lastly… the Meade Dobsonians are indeed “cardboard” tubes. They are spun into what’s known as “sonotube” – a rigid any very durable material. They have the advantage of being light, and are sealed at the ends to prevent moisture from creating a soggy mess. By the way, sonotube is used routinely, among other things, in construction to form concrete pillasters underground. The sonotube is NOT removed after construction and, even underground with full exposure to the elements, the sonotube material does not deteriorate for many years. The Coulter and Orion Dobsonian telescopes also use sonotube. It is a popular material for do-it-yourself telescope makers as well. Hope this helps!

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Question
watch… the picture on a Computer monitor, … take digital pictures and observe the stars away from the telescope.
Anwser
The first consideration is whether you are trying to steer the telescope in your back yard (say, less than thirty meters away), or need to access a telescope using dial-up telephone lines or an Internet link. I am using an LX200 equipped with a JMI NGF-S focuser with a Meade Pictor 216XT; I generally use either the Meade f/6.3 Focal Reducer or the Optec f/3.3 MaxField telecompressor for increased field of view and decreased exposure times. This arrangement requires two serial ports: one to connect to the CCD imager, and the other to connect to the LX200. I use Software Bisque’s TheSky, which, in addition to steering and tracking the telescope, also allows me to change the focus in minute, fairly reproducible increments. On initial setup, I use the manual focusing knob on the LX200 with a parfocal eyepiece for whichever setup I intend to use; this puts the focus “in the ballpark”. I install the CCD imager, then use the focus control in TheSky to fine-tune the focus. The JMI focuser has proved to be invaluable – focusing was by far the most time-consuming and frustrating element of CCD imaging prior to its acquisition. The software provided with the Meade Pictor has markedly improved over the last year; however, I would be much happier if Meade would provide the information necessary for companies like Software Bisque to provide support for the Pictor series in their excellent CCDSoft product. The integration between TheSky and CCDSoft is superb; I would be very happy to stay with Meade for my next CCD if I had other software options. Unless things change, I will probably make the transition to SBIG, although I might keep the Pictor to use just as an auto-guider. One problem with my arrangement (TheSky and Meade’s PictorView software) is that, in order to use the LX200 features of the PictorView software (AutoCenter, AutoMosaic, AutoFocus), one must suspend the link to TheSky. I have been unable to get the AutoFocus feature to work with my JMI focuser, and I prefer to use the mosaic feature of TheSky, so the AutoCenter is the only LX200 feature that I would like to use regularly. Due to the inconvenience of having to suspend the link to TheSky and then re-establish it, and check the synchronization, I generally just manually steer the telescope from the computer to center an image on the CCD chip. I’m sure there are better ways to accomplish some of these tasks, but this system seems to be working for the time being… Lastly, if you need to control your telescope over a great distance, Software Bisque also has remote control software which works over dial-up lines, and, soon, I am told, over the Internet. By the way, I consider myself a neophyte at CCD imaging; I am nothing less than amazed at the level of technology (and quality) that is available to the amateur/hobbiest astronomer at very reasonable cost nowadays.
Associated Telescope Computer Question: I recently purchased a Meade Magellan 1 Telescope Computer System. Everything appears to be set up correctly but I am having problems with the encoders. On page 3 of the users guide is says that to confirm that the encoders are activated and recording the telescope’s motion, see if the telescope’s coordinates change as the telescope is moved. I put the computer in the Coordinate Mode and the numbers only fluctuate slightly if at all. The “raw” coordinates do not appear to be working. Should these numbers be changing or am I missing something? I can’t seem to aligned the telescope in order to make it work. Any ideas?

• Anwser: I recently installed the Lumicon Sky VectorII on my 2080 and it works great. Maybe I can help you. 1. Are the encoder shafts turning with the unit? Probably best seen on the Dec rotation. 2. What scope did you install this to? 3. Make sure all connectors are pushed home. Have you tried to talk to Meade? Ha Ha, that’s a joke! I was wanting info from them and made 9 calls to them and there damn phony phone system routed me right out of the company and when I finally got a human on the phone he didn’t know diddly squat. So much for help from them!! The readout should show change in that mode, I’m thinking. Let me know. 29
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Question
They note in their magazine that the diameter of say Jupiter is 28.9″. I just want to be clear – that this is really 0 degrees, 28′ 56″ and NOT 0 degrees, 0′ 28.9″.
Anwser
No, if they say 28.9″, when referring to a planet’s angular size, the (“) after the number twenty-eight point nine means “seconds of arc”, and any (‘) means “minutes of arc, ect. Thus, the number would be read correctly as “twenty-eight point nine seconds of arc”, with no degrees or minutes indicated. This is the standard convention when talking about angular sizes for the planets. Sometimes, the “arc” is dropped after then quotation mark, with the number being then to be understood as being in seconds of arc (or “arc-seconds”). Today, Jupiter’s angular diameter is about 35.4 seconds of arc (35.4″), which is stated verbally as “Thirty-five point four seconds of arc”. Since none of the planets gets much larger than about a minute of arc (Venus can get to nearly 63″ arc at inferior conjunction, and Jupiter can get to about 49.8″ arc at the most favorable opposition) and most are usually noticably smaller than an arc minute, there is no pressing need to put the angular diameter number in a degree-minute-second-decimal format. In a similar manner, the angular size of the moon today is about 33.24 minutes of arc (33.24′), as generally, it is just left in the single minute-decimal number format, instead of being “split up” and stated “0 deg. 33 minutes, 14.4 seconds of arc”. The only time the full DMS format is usually used is when specifying the *coordinates* of a body and not its angular size, as in a Declination like +25 deg. 25′ 12.5″ (“plus 25 degrees, 25 minutes, 12.5 seconds”).
Associated Telescope Planet Question: Because suppose in an eyepieve giving me one degree FOV, there are 3600″, and say Jupiter would only measure 0.8% across my eyepiece even at 100x. (the 28.9 number is made up because I don’t have the magazine handy. It has now interested me because I am getting a telescope, and measuring fields of view of eyepieces, it seems to me that their notations for diameters are extremely small)

• Anwser:Yes, this is why you need quite a bit of power to get the view of the planet’s up to a scale where the eye can easily view them. An eyepiece alone has an “apparent” field of view, which is the angular span your eye sees when you are looking into one (even when it is *not* in a telescope). Eyepiece apparent fields of view are usually given in degrees (often from 20 degrees for small inexpensive ones, to upwards of 80 degrees for expensive “wide-field” eyepieces). Most *telescope* true fields on the sky when used with a specific eyepiece are measured in arc minutes or degrees, because again, that is a sort of “standard”. To a fair approximation, the true field is gotten by dividing the apparent field of the eyepiece by the power that eyepiece gives in the telescope. For example, if an eyepiece has an apparent field of 52 degrees, and yields 47x when in the telescope, the true field the telescope with that eyepiece installed would be about 1.1 degrees. My lowest power eyepiece in my ten inch Newtonian gives me a true field of view on the real sky of 1.063 degrees, or 63.78′ arc (at 47x). Either of these two formats would be correct and understandable among amateurs. Some amateurs might sometimes say “1 degree 3.78 minutes”, although again, most people rarely say “1 degree, 3 minutes, 46.8 seconds of arc”, as it is a little long and cumbersome. My highest “single” (ie: not Barlowed) eyepiece power in my ten inch Newtonian yields a true field of view of about 18.73 minutes of arc, which, even at the 288x this eyepiece yields, is still nearly 32 *times* larger than the angular width of Jupiter today. Even if I use my 2.5x Powermate, the field of view at 720x would be about 7.49 arc minutes, which is still over 12 times larger than the angular width of Jupiter’s disk this evening. Clear skies to you.
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Question
Yes domes have been struck by lightening on occasion. The dome of the University of Iowa Observatory has been struck twice with relatively little damage. I suppose this is because the dome is grounded. I was in the dome of the 40 inch refractor at Yerkes Observatory when it was struck, again with no apparent damage. The solar observatory at Sunspot New Mexico is in a region where there are many strikes per year, as a consequence they have extensive grounding systems for their domes.
Anwser
Oh, yeah! We do have a bit of a lightning problem here at Sunspot. The Vacuum Tower Telescope has taken many hits, as well as the domes. All metallic structures are indeed grounded, as well as having arrays of lightning rods around roof lines. The poor conductivity of the soil here makes these grounds somewhat ineffective at certain (dry) times of the year. A close strike or direct hit can really make the interior of a building or dome light up. Our biggest problem is protecting electronic equipment from the inductive surges on power and signal lines. Things are getting better in recent years with the installation of UPS’s with line conditioning and the replacement of lots of inter-building copper with fiber optic cables. Never had anyone killed or injured here as a result of lightning, as far as I know. There was the tourist, though, that suffered a mild electrical shock as they were gripping a metal handrail when lightning hit a nearby tree.
Associated Telescope Domes Question:Professional observatories have hugely expensive air circulation systems to try and circumvent this problem.

• Anwser:There are more factors at work here than just the presence of a dome – large professional observatories have a great deal more ’stuff’ in them: tens of tons of glass, hundreds of tons of metal, large industrial electric motors, and the like, all of which generate or hold heat. Of course they use climate control and other devices to get around these problems. For the amateur dome, there are only a few small sources of thermal problems. One is the heat of the observer and his or her gear, if any (computers and the like), which can tend to degrade seeing non-trivially if the slit is too narrow. A simple fix for this is a low-volume fan exhausting air out the north end of the observatory; or, one can build the observatory properly in the first place! Another source of thermal trouble is caused by somewhat slower cool-down. In my experience, the maximum time difference is less than 10 percent, which is trivial when one considers the dark adaptation and other benefits one gets. In some circumstances, domes can equal or exceed roll-offs in reaching thermal equilibrium. Some of this is, of course, related to knowing how to use a dome in the first place. A final source of trouble is not really thermal – it involves eddies of air washing over the slit in the wind, caused by the aerodynamics of the dome. Usually this problem is entirely undiscernible, but sometimes one can see it as peculiarly degraded seeing. Of course, in the roll-off, the wind is whipping around inside the walls and setting up similar eddies, equally noticeable; and also blowing on the telescope (I use a roll-off almost every night – I know what I am talking about on this!). In the dome, at least the scope isn’t blowing about. Of course, any of these conditions can be reversed or considerably changed if the respective observatories are not properly built. Roll offs are perhaps more “idiot proof” (sorry if that’s only a local slang), but then there are few idiots in astronomy.
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