Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Stargazing What can I get to improve telescope

  1. May 22, 2007 #1
    Hey there, I am new to this particular forum. I recently picked up a Meade starting level telescope (nothing electric). I caught a glimpse of my first planet last night and it was rad! I do not know which planet it was, but I assume it was Jupiter as it had some dots around it....they were either Jupiter's moons or I am mistaking and they were just distant(er) stars.

    The planet was exremely small in my viewfinder though, so my question is this:Can someone tell me. . . What is a good accessory to add to my scope to help me see things "better"....Is there a recomended lense?

    I have a Barlow lense, but I do not seem to benefit from it. I also have the lenses my scope came with: 25mm (I use that to spot things) 9mm(gets me sharper, I think) and a 17mm (I have not found a use yet).....

    I understand that magnification is not as important as resolution, but is there a way I can magnify things to a certain extent without compromising clarity?

    Thanks,
    Casey
     
  2. jcsd
  3. May 22, 2007 #2

    chemisttree

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    What is the focal length of your scope? A good planetary scope will have a fairly large focal length. A rough guide for the maximum reasonable magnification that your scope will produce is 50 times the diameter of the mirror in inches. A 4" mirror will at best produce useable images up to 200X magnification. That means that when viewing is optimal, 200X is the best you will do. At that magnification images will be shaky and will streak across your field of view.

    You may want to consider a low cost camera for your scope. I've seen some pretty decent images for planets using an unguided 4" scope. If you are serious about your hobby, try to buy the best accessories. These will be real investments that you can carry on to bigger and better scopes. I like the Televue line of lenses and magnifiers. If you go with a camera, a good 2X or 3X magnifier can be a real help. Televue has a magnifier they call the Powermate that will be just what you are looking for.

    Beware! As you buy better and better accessories (some as expensive as the scope you are now using) you are going to want (ie 'need') bigger and better scopes and mounts and cameras and locations and temperature controllers and image software and coma correctors and time and...

    http://www.televue.com/home/default_3.asp
    http://www.telescope.com/jump.jsp?itemID=0&itemType=HOME_PAGE
    http://www.meade.com/
     
  4. May 22, 2007 #3

    russ_watters

    User Avatar

    Staff: Mentor

    The telescope is listed in the next thread down...it is a 1000mm focal length Newtonian reflector.

    The best combination you'll probably be able to use is the 9mm and the barlow (I assume it is a 2x barlow). So that gives 1000/9*2=222x magnification. The maximum theoretical magnification is 350-400x, so you can use a 2.5x or 3x barlow to get more magnification. I wouldn't get smaller than that 9mm eyepiece, as they can be tough on your eyes.

    Jupiter rises near midnight, so if you were out late and saw up to 4 dots all along a straight line with the planet, that was Jupiter and they were the moons. At 222x magnification, you should easily be able to see horizontal stripes and the Great Red Spot if it is in the right position. The problem with Jupiter right now, however, is that it stays low to the horizon this year and as you are finding out, the atmosphere really kills the view. Adding magnification just makes it a bigger, fuzzier ball that even seems to 'swim' across the eyepiece. Most people when first looking through the telescope remark about how small the objects are, but your eyes are really good at resolving small details, so you should sill be able to see a lot.

    Stability on all telescopes is a big, big issue. You'll probably have to track slowly, allowing the planet to drift through the field of view while you aren't touching the controls, to make it stable. Even with my big, stable, motorized telescope, I have to tell people not to touch the eypiece, because they won't see a thing if they do. You'll get the hang of it. If there is an option for a motorized-drive (or if you are technically inclined...), that would allow you to track objects through the sky without touching the controls, making it much more stable.

    If you can get out not long after sunset, try finding Saturn - it is a very rewarding view, and since it is high in the sky, it should be much clearer.
     
  5. May 23, 2007 #4
    Russ, I am not sure what you meant by the next thread down. . . I do not think they stay in order for too long.

    I have gotten the hang of not touching anything while viewing, though getting Jupiter into focus is a real shaky time..

    However, No matter what combination of lenses I use, I cannot seem to see the features of Jupiter (i.e. the horizontal bands). All I can see is a bright dot with a string of 4 smaller white dots surrounding it.

    I know that my telescope is not the greastest, but I am quite sure that I should be able to make out some more distinct features.

    The largest that the planet appears in my viewfinder is the actual size of this asterisk-->*

    The image is quite crisp, but all of the sharpness in the world doesn't help if the image is too small for the human eye too resolve.

    I have a 2X Barlow that I bough with the scope. Along with three other lenses. These are the specs:

    114mm diameter, 1000mm (f/8.8) focal length reflector; rack-and-pinion 1.25" focuser with sleeve lock; equatorial mount with variable-tension locks; two 1.25" eyepieces (MA9mm and MA25mm) with rubber eyecups; diagonal mirror (1.25") Lenses:eek:ne 9mm (78x) and one 25mm (28x)
    and one 17mm(23x)

    I will keep trying:tongue2:
     
  6. May 23, 2007 #5

    chemisttree

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Does the telescope require that you collimate the mirror? Could the collimation be a little off?
     
  7. May 23, 2007 #6
    I am sorry chemistry; I have no idea what this means:redface: I do not recall hearing this term collimation in the instructions.
     
  8. May 23, 2007 #7

    russ_watters

    User Avatar

    Staff: Mentor

    True - I probably should have linked it for him....
    Is it really just a dot or does it have a definite size and disk shape? It is possible that it is due to atmospheric conditions lowering the contrast of the image, but it is possible that the telescope needs to be collimated like chemistree suggested, but only if you are using very high magnification.

    Collimation is a process for aligning the components of the telescope - for yours, that means adjusting the secondary mirror. I wouldn't worry about it quite yet.
    You absolutely should - it is possible to see the banding even with a large pair of binoculars.
    "viewfinder"? You mean the eyepiece?
    If the image is crisp, then it probably isn't an atmosphere or collimation issue, but simply a magnification issue. It sounds like you haven't used the barlow yet - definitely give it a try.
     
  9. May 23, 2007 #8
    Yes, I meant the eyepiece. And I have tried the Barlow. Whenever I encounter a problem of any sort, I usually investigate as thouroughly as I can on my own before posting here; I think I have tried every combination with the Barlow and other lenses; so maybe collimation is a problem. . . but I will attempt again tonight before messing with the scope.

    I thought that with the 2x Barlow and the 28x 25mm lense it would be enough. I will try again with the 78x 9mm and the Barlow even though it is hell on the eye.


    1. Do you remember the name of the thread?
    2. It does have definite shape and size. . . I use the word dot to emphasize just how small it appears though. I realize it will not be "huge" but it is ....this is so difficult to describe with words....
    I guess I could say that it is defined enough that I can see it is a disk (i.e. the edges are not blurred) but I can not make out any distinct features other than that (because of the size).
     
  10. May 24, 2007 #9

    chemisttree

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    I saw the other thread. Meade EQ-AST 1000 mm short tube. It has a relay lens in it to shorten the tube and increase the focal length. Is the relay lens achromatic? It is definitely not apochromatic... If it isn't, you could be having a problem with the lens causing the image to be fuzzy. The blue light will have a slightly different focus than the red resulting in loss in contrast.
    A contrast enhancer filter or a "mars" filter could do the trick.

    http://www.telescope.com/shopping/p...e=PRODUCT&iMainCat=6&iSubCat=22&iProductID=83
    http://www.lumiconfilters.com/filter-catalog.php?cid=18&cn=Lunar+&+Planetary+Filters
     
  11. May 24, 2007 #10

    russ_watters

    User Avatar

    Staff: Mentor

    No, chemistree, it is a Newtonian reflector - no lenses except in the eyepiece. Just a primary and secondary mirror.
     
  12. May 24, 2007 #11

    chemisttree

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    From the Meade site:

    SPECIFICATIONS
    Meade Model 114EQ-AST (P/N: 04056) — Basic model includes the same diameter mirror as above, but includes a special relay lens which shortens the tube length and yields a 1000mm focal length (f/8.8). Includes a somewhat smaller mount and tripod than the model above. The exact same accessories are present in both models...

    http://www.meade.com/starterscopes/eq_series.html

    Does the term 'relay lens' refer to a mirror?
     
  13. May 24, 2007 #12
  14. May 25, 2007 #13

    chemisttree

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Yes, I followed the link on the other thread. The EQ-114 ASTR. I assume that the 'R' stands for the Relay lens? Is there any other glass (besides the 2 mirrors) between the opening at the top of the scope and the focusser? I still think a filter might be a cheap (try) fix.
     
  15. May 25, 2007 #14
    I have never looked inside, so I really don't know. I was trying not to take anything apart, but I might have too. The only reason I did not think it would be the filter is that it is not that I can't idetify Jupiter's features due to clarity, but due to size. It is just so small...
     
  16. May 25, 2007 #15

    chemisttree

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    You should be able to see any lenses by inspection of the scope. No tools required. There shouldn't be any glass covering the opening on top. You should see the secondary mirror in the same plane as the focusser. The lens (if there is one) might be in the focusser tube.

    In my 4.5 in reflector, Saturn looks like a pea held at arms length when I use my 2X barlow and 9mm combination. The magnification with this combination is about 100X. Your magnification will be roughly twice that at 222X. You should see some detail and the image should NOT look tiny but definitely disc-shaped.
     
    Last edited: May 25, 2007
  17. May 25, 2007 #16

    russ_watters

    User Avatar

    Staff: Mentor

    I stand corrected - I've never heard of such a thing. Essentially, it is an integral Barlow lens, in the middle of a Newtonian reflector. And if there is only one element, it certainly would yield some chromatic aberration.
     
  18. May 25, 2007 #17

    russ_watters

    User Avatar

    Staff: Mentor

    Jupiter is small at 220x magnification, but it should be big enough to see stripes. Still, you can get a good 3x barlow from Orion (www.telescopes.com) for around $50 and that'll help increase the magnification.

    With the 9mm and the 2x Barlow, the view should look something like this (though with less contrast):
     

    Attached Files:

    • fov.jpg
      fov.jpg
      File size:
      8.5 KB
      Views:
      167
    Last edited: May 25, 2007
  19. May 25, 2007 #18

    chemisttree

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Wow! Great pic Russ! One of yours?
     
  20. May 25, 2007 #19

    russ_watters

    User Avatar

    Staff: Mentor

    Nooooo - it's a screenshot from Starry Night! I do have a recent one that is half-decent, though. I'll post it later.
     
  21. May 26, 2007 #20
    By less contrast, you mean the bands wont be as sharply defined right?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: What can I get to improve telescope
  1. What can I see? (Replies: 11)

Loading...