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Thread: WTB: Astronomy telescope

  1. #1
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    Default WTB: Astronomy telescope

    Looking for a complete of telescope for viewing stuff in the night sky.

    Around 3-inch, preferably with mount.

    Please PM if you have one to let go.

    Regards

  2. #2
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    3-inch may not give you much of a view.

    What's your budget?

    There is a lot of sales for Celestron Nexstar 114 GT on ebay for ~US$220 before shipping. You might be able to find some seller who are willing to ship to Singapore. It is a good beginner's scope with 4.5 inch f/10 aperture.

    I got one last week and got pretty good view of Mars, though not as good as ETX90RA. However the GOTO computer control is really very convenient, despite the noisy motor.

    ETX90RA can be bought at US$169 from www.sightandsoundshop.com. But they do not ship overseas. This scope has very good optics but the mechanical design is a total failure. I have been using this for a year and only managed to get the RA tracking to work last week.

    www.telescopehome.com has a lot of telescope reviews.

    All this can be considered OT because I am not offering a scope for sale to you. But hopefully this information is helpful to you.

    - Roy
    As complexity rises, precise statements lose meaning and meaningful statements lose precision.

  3. #3
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    Thanks!! I'm actually exploring the possibility of astrophotography in the future but thinking of starting with basic telescopy first. I have read a few websites on how to choose telescopes and there are as many opinions as there are sites on what's critical and what's not. Do you have any books that you'd recommend for a beginner? I'd probably need a telescope for general viewing of the night sky rather than ability to resolve deep-sky objects. Auto-tracking doesn't really appeal to me but I'll probably need that if and when I really go into astrophotography. In any case, I think Singapore's a lousy place for any form of critical viewing, given the amount of stray lights.

    I'll probably check out the shop at the Omni-theatre for a rough feel of the prices. Wai told me over the irc that it might be cheaper to import scopes rather than get them from local dealers. I've even come across sites that tell you how to build a newton reflector type of scope Might try building if I get hooked on this hobby...

    btw, think I was able to make out Orion nebula very faintly on a friend's 16x30+ binocs

  4. #4
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    Hi,

    Based on my brief experience with the ETX90 and the Nexstar 114GT, I would recommend that you get a catadioptic instead of a newtonian. The former requires less maintenance and is supposedly more suitable for astrophotography.

    Even though my limited experience in star gazing does not warrant me to claim that I have "out grown" the ETX90 and the Nexstar 114, I am already considering selling both of them and put it some more money to go for a NexStar 5 or Nexstar 8.

    I kind of like the design of Celestron Nexstar 4 also. You might want to consider this. It is as compact as the Meade ETX90, but has a slightly larger aperture and the mechanical design looks much better. ebay price is around US$350 to US$450 (http://cgi.ebay.com/ws/eBayISAPI.dll...category=28181). Or you can get it new from B&H for US$594.95 before shipping. http://www.bhphotovideo.com/bnh/cont...=218899&is=REG

    Review: http://www.telescopehome.com/celestr...exstar4gt.html

    For astrophotography you will need the necessary adapters and mounts and they are different for SLRs and digicams. Wai would be able to gove you all the details you need.

    Managed to locate the Andromeda galaxy last night and I was up until 1:30AM viewing it and Mars. The view is ok but not spectacular with the Nexstar but it was still very exciting to be seeing a real galaxy with my own eyes.

    Good luck with your telescope shopping!

    - Roy
    As complexity rises, precise statements lose meaning and meaningful statements lose precision.

  5. #5

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    Quote Originally Posted by kh_drew
    Thanks!! I'm actually exploring the possibility of astrophotography in the future but thinking of starting with basic telescopy first. I have read a few websites on how to choose telescopes and there are as many opinions as there are sites on what's critical and what's not. Do you have any books that you'd recommend for a beginner? I'd probably need a telescope for general viewing of the night sky rather than ability to resolve deep-sky objects. Auto-tracking doesn't really appeal to me but I'll probably need that if and when I really go into astrophotography. In any case, I think Singapore's a lousy place for any form of critical viewing, given the amount of stray lights.

    I'll probably check out the shop at the Omni-theatre for a rough feel of the prices. Wai told me over the irc that it might be cheaper to import scopes rather than get them from local dealers. I've even come across sites that tell you how to build a newton reflector type of scope Might try building if I get hooked on this hobby...

    btw, think I was able to make out Orion nebula very faintly on a friend's 16x30+ binocs
    forget abt the 1 at omni max. damn bloody expensive.
    try this

    http://www.harlequinastronomics.com/

  6. #6

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    Quote Originally Posted by kh_drew
    Thanks!! I'm actually exploring the possibility of astrophotography in the future but thinking of starting with basic telescopy first. I have read a few websites on how to choose telescopes and there are as many opinions as there are sites on what's critical and what's not. Do you have any books that you'd recommend for a beginner? I'd probably need a telescope for general viewing of the night sky rather than ability to resolve deep-sky objects. Auto-tracking doesn't really appeal to me but I'll probably need that if and when I really go into astrophotography. In any case, I think Singapore's a lousy place for any form of critical viewing, given the amount of stray lights.

    I'll probably check out the shop at the Omni-theatre for a rough feel of the prices. Wai told me over the irc that it might be cheaper to import scopes rather than get them from local dealers. I've even come across sites that tell you how to build a newton reflector type of scope Might try building if I get hooked on this hobby...

    btw, think I was able to make out Orion nebula very faintly on a friend's 16x30+ binocs
    Talk to me first before you wanna buy anything! If not, people will sure overcharge you. Especially in this astro market where most people do not know the true value of scopes and stuff. And forget about buying from the Science centre unless you have really so much spare cash to spend.

    Give me a PM and let me know your budget and I will get one for you.

  7. #7
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    I always imagine if I lived in the States, I would've mail ordered an LX90. Now I imagine ordering a 8" LXD55 Schimitt-Newtonian and view the stars in the Californian night sky. Too bad I'm trapped in the sunny island called Singapore.

  8. #8

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    maybe I'll get a bit longwinded today and post sth up ?


    there're a couple more local dealer here anyway.
    http://www.star-matrix.com/
    for eg,
    I think there's a Celestron dealer somewhere here too.
    alt to check out also if ya want to get from overseas
    www.astromart.com

    ya have been warned I guess, just like getting a camera, a scope's not cheap! or coz ya can always settle for sth lesser.

    given a "good" sky, I'll say even a 3" will perform! (hey I saw the triangulum Galaxy with a 80mm)
    but astro imaging IMO is really very technical. more then just sticking the cam behind the scope....
    with the modest set up, ya'll need @ least a GEM.... & we're talking bout motorised unless ya like to handtrack for 10 mins ?


    a newtonian might kill the fun unless ya're prepared to do colimation yaself. A refractor will be nice but of coz it can get pretty 'high' on ya waller if ya ever got greedy then... a dobsonian will be fun! someone here actually made a 8" I think. & as we're posting now, I think another one is on its way here a 10" ? a cat. shld be Idea I guess. but it ain't come cheap then.

    eyepieces if small is just as equally important! ya'll need to spend some cash on that little thing then

    there's a local mailing list ard
    http://groups.yahoo.com/group/singastro/

    we just got back from malaysia. andromeda galaxy is a naked eye object!

    and before ya know it. ya'll be talking bout resolution and contrast of scopes and eyepieces like ya used to for camera and lenses...

  9. #9

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    For the expert in Astromlogy out there, can I know your opinion on the price and quality of the telescopes in this website?

    http://www.mcgill.com.sg/shop/

  10. #10

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    Quote Originally Posted by blurblock
    For the expert in Astromlogy out there, can I know your opinion on the price and quality of the telescopes in this website?

    http://www.mcgill.com.sg/shop/
    I know the owner.....

    The price is ok.....but you may have to wait.

    As I said, get it through me if you wanna save money. Most shops will chop you if they know you are a newbie at this.

  11. #11

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    Quote Originally Posted by blurblock
    For the expert in Astromlogy out there, can I know your opinion on the price and quality of the telescopes in this website?

    http://www.mcgill.com.sg/shop/
    Don't buy anything yet. I suggest you attend some of the observation before making any decision. Join Yahoo group "Singastro" for details or talk to Starman first. Real astrophotography can cost you an arm and leg plus all the sleepless night before you get any decent picture.

  12. #12

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    are there any sites with actual pictures taken by the telescopes
    reviewed on telescope home/

    they all say waht "saturn and its rings looking like a giant flying saucer, colors of jupiter etc viewable, can see polar icecaps etc on mars, cassini division viewable"

    any PICS to back it up?
    how large pics are we talking about?

    VERY large detailed pics?

    any site with pics taken at home with telecope + digicam?

    doesnt matter if pics are taken in the us...

  13. #13

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    http://www.licha.de/AstroWeb/gallery...nu.php3?iWho=0

    anyway just checked the pictures out on the above... AMAZING!!!

    whats the method of taking these pics?
    For this pic:

    wat does it mean by:

    "The image is the result of stacking 1700 frames from 17 different AVI files"

    u mean u can't just take a long exposure with digicam and get pic like that?

  14. #14
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    Quote Originally Posted by marican
    [url]"The image is the result of stacking 1700 frames from 17 different AVI files"

    u mean u can't just take a long exposure with digicam and get pic like that?
    Taking a single frame shot of a planet is often a frustrating game of the planet being out of focus .. with film it's a lottery and it can take hundreds of frames to get a really good single shot. The reason for the high number of bad frames is due to a number of factors the major ones being:

    1) Atmospheric turbulence.
    Air acts like a lens, small columns (eddies) of differing temperature cause different levels of refraction and thus bring the image in and out of focus. This is also the reason why stars scintilliate (twinkle).

    2) Camera induced vibration.
    All cameras have a certain amount of vibration, the amount is often enough to cause the telescope and mounting to vibrate slightly when the shutter is released. Using an air-release can help alleviate this cause of bad frames but isn't always a cure.

    3) Ground induced vibration.
    Telescopes are very prone to vibration, especially modern designs that use lightweight mounts and undersized shafts etc. The slightest movement of the mount by ground vibration can be sufficient to ruin an image. Depending on the surface the telescope is mounted on even moving your foot can have detrimental effects.

    4) Combined focusing errors.
    Focusing for astrophotography is critical. Sadly most SLRs/DSLRs viewfinder screens are too coarse to achive really accurate focusing (not all are) and for non planetary work are often too dim to achieve accurate focusing on their own. Couple this with telescope induced focusing problems such as vibration when focusing and the entire scenario can be a real nightmare. There are solutions to the problem including esoteric fixes such as knife edge focusing (a device that replaces the camera for focusing), parfocal eyepeices (an eyepiece that is set up to exactly focus at the same point as the camera body) and various focusing masks that produce multiple images (Hartman masks) of the object that combine in to one image when focus is achieved. Other less frequently seen methods include diffraction spike focusing for stars and so on. As to how critical the focus is, in many cases a movement of 0.025mm is enough to throw the focus right out.

    Stacking is a method of overlaying images on top of each other, the idea being that each image overlayed increases the detail shown while reducing the noise levels in the final image. This allows shorter exposures and facilitates the use of certain webcams (such as the Philips Toucam Pro PCVC 740K, Quickcam Pro 3000 etc) to be used for quality astrophotography.

    So what the guy has done is to stack 1700 images taken from 17 different video files shot over a period of time (perhaps an hour, maybe a night or more) to produce the final image.

    On a final note, DSLR's are capable of doing quite a good job on the brighter objects in the night sky, however for faint objects (such as most galaxies) a DSLR doesn't offer a long enough exposure. Modified webcams can do 2-3 minutes while film can be used out to several hours. Specialist digital astro-cameras (known to astronomers simply as ccd-images or ccd-cameras) are made and feature such things as massive cooling systems to reduce the amount of noise, long exposure times (the best can do several hour exposures) and prices to match. Commercial units cost from about 1000 USD to well over 40,000 USD and the cost of top end reseach ccd-cameras can be 1/4 Million USD or more depending on the ccd sensors used and the type of cooling and electronic systems employed (eg: liquid nitrogen cryogenic cooling, vacuum evacuated sensor compartments, backlit ccd arrays and ultra low noise electronics).

    PS: hope you have the owner of the saturn image's permission to link to it.
    The Ang Moh from Hell
    Professional Photography - many are called, few are chosen!

  15. #15
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    even a bit of wind also can cos vibration, no wonder pple get a portable dome or even build one to protect the scope from wind. Also no mount can track 100% perfectly for long exposure

    I will be modding the Philips Toucam this way

    http://astro.ai-software.com/toucam2.html

    for longer exposure and use ice pack to cool the CCD

    is the modding methods in that site ok or have u come across other site that gives better methods? Thanks!

  16. #16
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    Impressed by the all-webcam Messier shots. Not the very best but it's it's good enough for Sky and Telescope. Of course, it's not fair to compare with thousand dollars CCD imagers.

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    Quote Originally Posted by Wai
    even a bit of wind also can cos vibration, no wonder pple get a portable dome or even build one to protect the scope from wind. Also no mount can track 100% perfectly for long exposure

    is the modding methods in that site ok or have u come across other site that gives better methods? Thanks!
    Wai, I'd head over here to qcuiag group for links to more modifications based on Steve Chambers designs.

    Packing in ice will work, but it's messy and doesn't last long you are far better off using a fan or peltier cooling. At present I'm not using cooling on my Toucam as the nights are cool enough though I've designed and engineered a hefty cooling system and case mod using multiple stage peltier cooling and a vacuum chamber which is currently being machined up for the summer. (it's a big job).

    You aren't quite right about no mount can track 100% for long periods. any mount that is aligned to within a couple of arc seconds and that has drives capable of sub 5 arc second uncorrected period error or zero PEC (such as friction and cable drives) is capable of unguided imaging for upwards of 60 minutes. Sadly such mounts cost serious money and are beyond the scope of most amateurs and most research institutions but they do exist (eg: UK Schmidt, AAT etc).
    The Ang Moh from Hell
    Professional Photography - many are called, few are chosen!

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