zoso1234
journeyman
Reged: 11/09/07
Posts: 8
Loc: Minnesota
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I just bought a Celestron StarHopper dob 8" used for 250.
it came with a telrad and a assortment of 7 lenses(ultima). the guy who sold it to me said he hadn't used it in a couple of years and it would probably need to be cleaned. the primary mirror has noticeable dust. it did not come with a dust cap. should i take apart and clean right away or will it not make much difference.
also should i buy a dust cap
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Protheus
Vaguely offended
Reged: 09/01/07
Posts: 4619
Loc: Illinois, US
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Well, first welcome.  I'd leave the scope assembled, and not worry about the dust for the moment. Did it come with a collimation cap?
Most importantly, just try to get a good look at something through it.
Do you have some astronomy software? Stellarium is pretty nice, and also free. It think this kind of thing is one of the most useful tools for an amateur astronomer. It's right up there with the cloudynights account in my list of stuff no amateur astronomer should be without.
Chris
--------------------
"To tread the sharp edge of a sword;
to run on smooth-frozen ice,
one needs no footsteps to follow..."
"Well, people sometimes ask me 'how did you get involved in astronomy?' I said 'I got born, what's your problem?'" -- John Dobson
"In discussing the large-scale structure of the cosmos, astronomers sometimes say that space is curved, or that the universe is finite but unbounded. Whatever are they talking about?" -- Carl Sagan
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zoso1234
journeyman
Reged: 11/09/07
Posts: 8
Loc: Minnesota
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thanks for advice, it did not come with a collimation cap, is that something i should get? What is a good website to buy things like that?
i do have Starry night which i do enjoy not sure if it is like stellarium though.
steve
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Protheus
Vaguely offended
Reged: 09/01/07
Posts: 4619
Loc: Illinois, US
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You'll eventually want something to use for collimation, but it's probably not urgent. For now, if the secondary mirror is facing out towards the eyepiece, and if you can see the reflection of the spider assembly kind of near the middle when you look at it, don't worry too much. Later you can purchase or make a collimation cap, or some other tool to help you get things lined up.
Quote:
i do have Starry night which i do enjoy not sure if it is like stellarium though.
Probably close enough.
Chris
--------------------
"To tread the sharp edge of a sword;
to run on smooth-frozen ice,
one needs no footsteps to follow..."
"Well, people sometimes ask me 'how did you get involved in astronomy?' I said 'I got born, what's your problem?'" -- John Dobson
"In discussing the large-scale structure of the cosmos, astronomers sometimes say that space is curved, or that the universe is finite but unbounded. Whatever are they talking about?" -- Carl Sagan
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Ouranos
sage
Reged: 11/07/06
Posts: 325
Loc: Illinois
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I used to own the 6" version of your scope. I agree w/ Chris. I would do some looking through it first. I eventually ended up cleaning my mirror, but only after a bug had slimed it. I found these scopes hold their collimation pretty well. I have an extra collimation cap around, I think. Send me a PM with an address and I will be glad to mail it to you (free). It would get you started on the journey of collimation. Or, some guys make their own using a film cannister.
Paul
Paul
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East/Central Illinois
Orion XT10
Celestron Omni 102
SV Nighthawk 7
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Jim Haley
sage
Reged: 07/04/07
Posts: 247
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I agree...just use it!
Is there anyone knowledgeable that can help you? Astronomy clubs and science museum sometimes have public star parties. Any enthusiast can probably help as well.
Two great websites for equipment.
Telescope.com
Astronomics.com (Astronomics sponsors this website)
You might consider an introductory book like Nightwatch by Dickinson or Turn Left at Orion. Another really good book for new dob owners is Astronomy Hacks. Weird title but great book!
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Jim Haley
12.5" f6 Starsplitter Dob
Orion 8" XTi (with computerized object locator)
Orion 114EQ reflector
80mm f6 refractor
Edited by Jim Haley (08/22/08 02:29 PM)
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zoso1234
journeyman
Reged: 11/09/07
Posts: 8
Loc: Minnesota
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Thank you all for the help. Hopefully the conditions tonight will allow me to do some observing.
I don't personally know anyone that is knowledgeable with telescopes but the astro club sounds like a great idea. i live pretty close (45 min) to the twin cities so i should be able to find one.
I looked through a couple of websites (telescope.com & astronomics) and i still can't seem to find a collimation cap or dust cap. Do most of you guys use a cap to keep dust out.
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Protheus
Vaguely offended
Reged: 09/01/07
Posts: 4619
Loc: Illinois, US
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Which twin cities?
Personally, I use a cut up piece of foam to keep dust out.
Chris
--------------------
"To tread the sharp edge of a sword;
to run on smooth-frozen ice,
one needs no footsteps to follow..."
"Well, people sometimes ask me 'how did you get involved in astronomy?' I said 'I got born, what's your problem?'" -- John Dobson
"In discussing the large-scale structure of the cosmos, astronomers sometimes say that space is curved, or that the universe is finite but unbounded. Whatever are they talking about?" -- Carl Sagan
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zoso1234
journeyman
Reged: 11/09/07
Posts: 8
Loc: Minnesota
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minneapolis & St.paul MN
foam sounds like a good idea
steve
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Protheus
Vaguely offended
Reged: 09/01/07
Posts: 4619
Loc: Illinois, US
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Quote:
minneapolis & St.paul MN
foam sounds like a good idea
I have some friends around there, but they're non-astronomers. Remember that there are different types of foam, but only some will work for this. You want a compressible (springy) kind of foam that won't break apart and leave statically charged packing-peanut bits all over your objective.
Chris
--------------------
"To tread the sharp edge of a sword;
to run on smooth-frozen ice,
one needs no footsteps to follow..."
"Well, people sometimes ask me 'how did you get involved in astronomy?' I said 'I got born, what's your problem?'" -- John Dobson
"In discussing the large-scale structure of the cosmos, astronomers sometimes say that space is curved, or that the universe is finite but unbounded. Whatever are they talking about?" -- Carl Sagan
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Charles Laird
super member
Reged: 08/24/07
Posts: 109
Loc: Kerrville, Texas
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I have the same scope. I second what everyone has said. I will give you a link to help you evaluate the collimation of the scope. You can do a rough collimation without even the cap but the simple cap makes it a lot easier. That is an f6 scope which will tolerate rough collimation better that on the bigger aperture scopes. I got mine used and the collimation was so far off that I could not even find a bright full moon. There is an allen screw at the very center bottom which needs to be loosened a little to adjust the collimation screws, then tightened back up...just not too tight...not working on a bulldozer here. The mirror on this scope is a little different. It has only one attachment point at the very bottom because it is molded into a curved shape rather than having a flat bottom. If it is exactly like mine it does not have a spider to hold the secondary; instead it uses a single post. Telrads are great providing that you do not suffer from too much light pollution. If you find that you are having difficulty seeing enough stars through the Telrad you may need to use an optical finder. In which case I would recommend a right angle correct image design, it is much less confusing and what you see through the finder is what you see on the chart. As far as charts go I highly recommend the Pocket Sky Atlas. It sounds like you are well equipped with eyepieces, ultimas are very good. I am still a beginner myself and find that I get far more use out of my lower powered eyepieces 32mm and 20mm I find to be the most useful.
Here is the collimation link:
http://www.piscescs.com/astro/collimat/notools2.html
Clear skies,
Charles
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"Nothing is too wonderful to be true."
Michael Faraday
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zoso1234
journeyman
Reged: 11/09/07
Posts: 8
Loc: Minnesota
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thanks again
I just took a 2nd look through my all lens and caps and luckily came across a coll. cap. when looking through i can see it is only a little off center. the secondary mirror looks to be a little shifted to the left. im guessing its close enough for now.
as for the lens, when i first get to take this bad boy out which lens should i start off with.
I have a 7.5mm, 12.5, 18, 24, 35 and 2x barlow and 25mm wide angle(all ultima except the wide which is just celestron?). All of them seem to be in pretty good condition i read a little on cleaning them and used a boat load of Qtips to get all the dust off them. No big scratches but some smudges that i didnt feel comfortable removing. is there a good cleaning product i should use or Distilled water?
it also came with 2 filter i think. one has a yellow tint and the other is pretty dark. i couldn't find much on them since all these products were made in the late 90's i believe 97.
there both Celestron one is No.8(yellow) and No.96(tinted).
my next step is to look for a good atlas and you all have gave some good recommendations.
thanks again
steve
Edited by zoso1234 (08/22/08 05:42 PM)
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Protheus
Vaguely offended
Reged: 09/01/07
Posts: 4619
Loc: Illinois, US
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To start out, I would use a low magnification eyepiece. The 35mm is the lowest you have. Try that, or the 25mm WA. This should make it easier to find things in case your finder scope isn't aligned properly with the main instrument (which is somewhat likely)...
Jupiter is really bright and easy to find in the southern sky right now, and might make a good first thing to look at. Also, if you can adjust the thumb-screws on the finder quickly, you can align the finder scope on it. It will be really prominent in the finder, and you'll be absolutely certain of what you're looking at in the main scope.
Chris
--------------------
"To tread the sharp edge of a sword;
to run on smooth-frozen ice,
one needs no footsteps to follow..."
"Well, people sometimes ask me 'how did you get involved in astronomy?' I said 'I got born, what's your problem?'" -- John Dobson
"In discussing the large-scale structure of the cosmos, astronomers sometimes say that space is curved, or that the universe is finite but unbounded. Whatever are they talking about?" -- Carl Sagan
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vinnie
Latinist
Reged: 01/05/08
Posts: 1444
Loc: Queensland, Australia
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Hi Zoso
Welcome to CN!
I women's shower cap makes a good dust cover for the open end of the scope
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Joe Aguiar
professor emeritus
Reged: 02/10/07
Posts: 705
Loc: Toront,Ontario
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Most new people look at telescope optics & always think they have to clean off the dust because they think it has to be 100% dust free. Leave it as it is for now & just enjoy viewing,unless there 1" thick dust & I would not worry about it too much for now.
Joe
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RussL
Music Maker
Reged: 03/18/08
Posts: 1572
Loc: Cayce, SC
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Quote:
I women's shower cap makes a good dust cover for the open end of the scope
Beat me to it, Vin. That's what I use on both ends of my RV-6 tube. (Who says there's women's?). 
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--Russell
"Akita mani yo." Observe everything as you walk. (--Lakota)
Celestron Celestar 8 Standard SCT, f10
Celestron 80mm Wide View ref., f5
Criterion RV-6 Dynascope, Newt., f8, (c. 1962)
Sears Discoverer 60mm ref., f7, (c. 1973)
Celestron Ultima DX 10x50, 6.5 TFOV
Tasco 7x35 wide
Several mediocre eyepieces
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zoso1234
journeyman
Reged: 11/09/07
Posts: 8
Loc: Minnesota
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i just got done doing some observing mostly looking to observe something. I spent most of my time focusing on Jupiter which i could get under low mag. i could just make out some of the belts.the higher in mag(using smaller lens) i went the more difficult it was to find jupiter. The guy who sold it to me put in a "lazy susan" (rotator) on the base unit, which at first I thought was a great idea, but after using it i know it has to go. i could not keep it steady for the life of me, every little wind gust would have me all over the place.
i also need to align the finder scope because it is not even close. The telrad is pretty cool, but it also needs to be aligned a little.
I then went on to the moon which was breath taking.it was so clear and big, the craters were huge and could even make out the ejecta or maybe the rille?(old lava tracks).
some questions for you guys
when observing the moon do you need a filter at all because afterwards my viewing eye felt like it had a tinted filter over it,everything was darker than my other eye. is this okay or is this causing damage?
I did all of this in my front yard which has some street lights and cars coming by, once i get the finder and telrad properly aligned i will be going somewhere more secluded.
Are there certain things that i should bring along?
i think i can figure out during the day how to align the finder scope but the telrad i'm not so sure. do you need to do that during the night?
also when you over or under focus on something bright is it normal to see your secondary mirror, somewhat like seeing through the collimator cap?
Edited by zoso1234 (08/23/08 02:07 AM)
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Protheus
Vaguely offended
Reged: 09/01/07
Posts: 4619
Loc: Illinois, US
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Quote:
The guy who sold it to me put in a "lazy susan" (rotator) on the base unit, which at first I thought was a great idea, but after using it i know it has to go. i could not keep it steady for the life of me, every little wind gust would have me all over the place.
Most dobs rotate this way. It's not as if they expect you to pick the telescope up to rotate it or scoot it around on the ground. Are you sure you don't just need to adjust the tension so it doesn't rotate as easily?
Quote:
when observing the moon do you need a filter at all because afterwards my viewing eye felt like it had a tinted filter over it,everything was darker than my other eye. is this okay or is this causing damage?
No damage. The moon is no brighter through a telescope than without, and no brighter at night than during the day. Of course, lots of us are somewhat less than comfortable observing the moon without a filter, as you've just found out.
Quote:
i think i can figure out during the day how to align the finder scope but the telrad i'm not so sure. do you need to do that during the night?
You can probably do both during the day and at least get them close. Pick a distant target like a radio tower or something, and make sure it's well away from the sun; you don't want to accidentally get an eye-full of that.
Quote:
also when you over or under focus on something bright is it normal to see your secondary mirror, somewhat like seeing through the collimator cap?
Yes, you'll start seeing the shadow of the obstruction when you're well out of focus. You'll also see "diffraction spikes" on bright objects, when they're in focus.
Chris
--------------------
"To tread the sharp edge of a sword;
to run on smooth-frozen ice,
one needs no footsteps to follow..."
"Well, people sometimes ask me 'how did you get involved in astronomy?' I said 'I got born, what's your problem?'" -- John Dobson
"In discussing the large-scale structure of the cosmos, astronomers sometimes say that space is curved, or that the universe is finite but unbounded. Whatever are they talking about?" -- Carl Sagan
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vinnie
Latinist
Reged: 01/05/08
Posts: 1444
Loc: Queensland, Australia
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Hey again Zoso,
Two points:
First the moon, no it won't harm your eyes, and purists will insist that no filter is needed, but I do find it to be uncomfortable, like just being photographed with a flash. A filter is not a bad idea.
Alignment of finders of any nature can be easily done in daytime using a distant object, like a radio tower (as Chris said) or a mountain or a tree on the horizon. You may need to *fine* tune after dark, but it really is a battle to start from scratch after dark.
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Jim Haley
sage
Reged: 07/04/07
Posts: 247
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For a dust cap, I used to use a shower cap. I used duck tape over the shower cap (while installed to make it stronger.
Later, I purchased some roof flashing and used that for the "sides" of the cap. I cut out a metal circle (or cardboard or whatever) for the center. Then I moved and only had access to cardboard so I just made a cap out of that (sides and center). After it was complete I "sealed" the cardboard with clear packing tape.
Hope this helps.
You can make a colllimation cap from a 35mm film holder. Just by added a tiny hole (see website below) . Actually 35mm film holders are also great for "plugging" your focuser when scope is in storage. Everyone can pick up a few at the photo stores for free (you might have to ask them to keep them for you) however fewer and fewer people use film.
Here are instructions.
http://www.lymax.com/cosmicone/collimator/index.shtml
--------------------
Jim Haley
12.5" f6 Starsplitter Dob
Orion 8" XTi (with computerized object locator)
Orion 114EQ reflector
80mm f6 refractor
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