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Stargazing Finally Ordering New Telescope

  1. Aug 8, 2007 #1
    I have been talking on this forum with some folks about telescopes and it seems that this is where I have been getting the best info. I have been looking to purchase a new scope for a couple of months now. After some research, it seems that buying something under $400 is almost garaunteed to dissapoint in some way or another.

    I have narrowed it down to a few choices, hopefully someone can give a second opinion before I commit. Man I hate online purchases, but what can I do....

    This seems like the most likely candidate http://www.telescope.com/shopping/p...RODUCT&iMainCat=4&iSubCat=8&iProductID=252655
    I would get the Non-Go To model. I am correct to say the the EQ mount is what is needed to take photos...right?

    Can anyone clarify what it is that causes the huge $$ difference to in this one? It is the same 8" aperture..I am guessing that it is just the overall quality. http://www.telescope.com/shopping/product/detailmain.jsp?itemID=252656&itemType=PRODUCT&iMainCat=4&iSubCat=8&iProductID=252656

    The other candidate is this monster http://www.telescope.com/shopping/p...RODUCT&iMainCat=4&iSubCat=8&iProductID=252217

    Now I am fairly certain I cannot take photos with this.

    I had never really considered taking photos, but for some reason, not having that option seems to be a real turn-off from the Dob. I know portability would be much easier with the EQ...but I do have an SUV (unfortunately) so that shouldn't be an issue.

    Any advice would be appreciated,
    Casey
     
    Last edited: Aug 8, 2007
  2. jcsd
  3. Aug 8, 2007 #2

    mgb_phys

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    Finding objects is obviously easier with the equatorial.
    Dobs generally require a better knowledge of the sky and careful calibrated arm muscles. You can't really take photos with a Dobs.

    I can't see any real difference between the two 8inch, the decider is usually the range and qaulity of the eyepieces supplied. The eyepiece makes a lot of difference to the quality of the viewing.
     
  4. Aug 8, 2007 #3
    Nice. My gut is telling me to go with the $629 model. I can always get new eyepieces later. I am just looking to find a relatively versatile upgrade from the $149 brand new POS that I currently own. I have had it for months, and have put more effort into trying to make it function properly than I have spent time enjoying the views.

    Casey

    p.s. (stupid question) How do I insert a hyperlink in these forums? html doesn't work and the "insert link" button does just what you see above. How do I condense it?:redface:
     
    Last edited: Aug 8, 2007
  5. Aug 8, 2007 #4

    turbo

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    The biggest difference between the EQ-mounted Newtonians is the beefiness of the mount. The more expensive one also has an upgraded focuser, and the text implies that it has a better primary mirror, too. If you want to take pictures through a scope, you're going to need a beefy, stable mount, and you'll have to add a guidescope. If you want to do very long exposures, and want to auto-guide, you'll also need a second digital imager, a computer, and guiding software that is compatible with your mount. As you can see, astrophotography is a more expensive proposition that it might appear at first. If I were in your position (knowing what I know now after over 40 years in the hobby), I would forgo photography for now and get the Dobsonian. You'll always like having that light-bucket around. Then, as you learn your way around the sky and gain experience, if you still have the desire to spend the time and effort to try your hand at astrophotography, start budgeting for a nice little apochromatic refractor on a mount that is at least one size up from the one offered as standard equipment. Short focal-length refractors are very popular with astrophotographers and lots of these people are producing stunning images with scopes of very modest aperture. Check out Greg's images, taken with a Takahashi 90 mm refractor. Noel Carboni does Greg's image processing, and the quality of the images emerging from their collaboration is outstanding.

    http://www.newforestobservatory.com/

    Edit: I have owned lots of scopes over the years and currently have a 6" Astro Physics APO refractor with a 90mm Vernonscope APO used as a finder/guider. I still would like to have a Dobsonian light-bucket, though, and will probably get an Orion 12" someday.
     
    Last edited: Aug 8, 2007
  6. Aug 8, 2007 #5
    There's 1 for the bucket! I appreciate your insight Turbo-1. It is a tough decision. Obviously the 12" has huge aperture; however, it still is a wee bit more than I would like to spend. However, the main reson I put the 12" as an option is this: If I were to get an 8" Dob, I would rather just get an 8" EQ (I have a feeling I like the mount better)....so if I were to get a Dob, I need to justify not getting the EQ by getting a much larger mirror.....

    I know my logic is that if a rubber-room patient, but it's just that.

    Casey
     
  7. Aug 8, 2007 #6

    turbo

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    No problem! For your consideration, there is also the matter of resale value. If you decide that you are getting bored with astronomy or just not putting in the time and effort to learn to get the most out of your scope, the 12" Dobsonian will be a much easier sell than an 8" Newtonian. Think of it this way - lots of people jump into astronomy at the 8" aperture with a Meade or Celestron SC. Are they going to be interested in buying your 8" Newtonian if you should decide to sell it? Probably not, but there are lots of people like myself who have nice scopes of modest aperture that wouldn't mind adding a light-bucket to the line-up, if only for the bright wide-angle views of DSOs. Sometimes you can accept less-than-perfect optical performance if the trade-off is aperture. Even if you bought the Newtonian with the beefier mount, upgraded focuser, upgraded primary, you couldn't get me interested in it unless you were willing to take a huge loss on it, and maybe not even then.

    Now the 12" is another story entirely. Theoretically, it should gulp up 4x the light of my refractor, if you ignore the central obstruction of the Dob. If you've got a buddy with an 8" SC, he'll be tempted by that Dob, since it will more than double the light-gathering capacity of his SC. As long as you're not dead-set on astrophotography, the Dob is the safer purchase.
     
  8. Aug 8, 2007 #7

    mgb_phys

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    Remember to use it and enjoy it rather than worry about apertures and eyepieces and mirror figures !
     
  9. Aug 8, 2007 #8
    Good point mgb phys! I am just trying to do a little research this time. The last time I did not, I was extremely dissapointed; life is full of dissapointments but I really hate having to pay for them!
     
  10. Aug 9, 2007 #9

    Chronos

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    Portability becomes a serious issue at aperatures greater than 8". Let's just say you will rarely care to take it camping. If, on the other hand, you live in the great outdoors with space to build an observatory, buy all the aperature you can afford. It will become your second wife.
     
  11. Aug 9, 2007 #10
    Good point. Now that I have slept on it, I realize that maybe the 12" is rather large. I had origanlly said that portability should not be an issue..but I think it was just wishful thinking...I'm wicked scrawny and so is my girlfriend; we'd look like a couple of jerks moving that thing! (I am am obviously from Mass; I can't believe I used wicked on Physics Forums:)

    Casey
     
  12. Aug 9, 2007 #11

    turbo

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    The assembled weight is 81#, and the weight of the OTA (the heaviest section) is 50# - the weight of a box of nails or a concrete block. That's not a lot of weight unless you're REALLY wicked scrawny. :rofl: The more important issue is that a large scope will be quite cumbersome and will require a roomy vehicle for transport. My 6" refractor with mount and tripod and counterweights probably tops out at around #150 - almost my weight - though it can be assembled in sub-assemblies of manageable weight, The heaviest assembly is the GE mount with counterweights, and I have to lift that to head-high to set it on the cradle of the oak tripod. Be aware that if you go with the 8" Newt on the Atlas mount, the assembled weight is 95#, plus any rings/guidescope, etc. The Dob is mostly empty tube - it's the size rather than the weight that should concern you. If you don't have room for safe storage and transport of the Dob, then it's not for you.
     
  13. Aug 9, 2007 #12
    The 8" I am looking at is 62 lbs. assembled according to the specs. I have noticed other 8"ers weighing a substantial amount more. Why is that? Heavier tripod? I am expecting a relatively stable tripod with this one; obviously not of the highest quality, but of decent.

    Casey
     
  14. Aug 9, 2007 #13

    turbo

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    Yes, heavier mount and tripod comprise the extra weight. If you eventually want to do astrophotography with that rig, you will find that the standard mount might not have the load-bearing capacity and/or rigidity necessary for good results. The second 8" you listed in the OP is on the Atlas mount, and that is probably the lightest mount I would buy for an 8" Newtonian, unless it would only be used for observing. Adding a guide scope, guiding camera, imaging camera, etc puts extra load on the mount, so if you're planning on doing that sometime, you should consider saving more money and getting a real beefy mount. My mount is no-frills, heavy as all get-out with large shafts and bearings and gears, and I wouldn't have it any other way. It's rock-steady, even in gusty winds and that is essential for astrophotography.
     
  15. Aug 9, 2007 #14
    Nice. I think I will just limit myself to an observing scope for now and do something like you said earlier with the small refractor. I still need to just pic one and purchase!

    Thanks again,
    Casey
     
  16. Aug 9, 2007 #15

    turbo

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    That's not an unreasonable path, Casey. You can buy a short-focal length refractor and adapt it to that mount, along with a small, longer-focal-length refractor as a guide scope and end up with a nice little imaging rig.
     
  17. Aug 9, 2007 #16
    BTW. The 8" has a 1000mm focal length (f/4.9). I always have difficulty with these numbers; that should be decent for deep space and planetary observation right?
     
  18. Aug 9, 2007 #17

    Chronos

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    A good compromise, IMO, Casey. You get good portability at f5, nice aperature and affordability. The wide field view will be spectacular, and on nights of good seeing 200x is easily achieved. This is good first scope that will hold its value if you later chose to trade up.
     
  19. Aug 10, 2007 #18

    russ_watters

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    Sorry I hadn't responded to this thread, I was away on business for a week...
    Focal ratio is the ratio between aperature and focal length. Ie, 8" is 203mm, 1000/203=4.9.

    Focal ratio gives you an idea of how bright objects will appear in the scope - the lower the number, the brighter objects are. It is more often useful for photography because the detectors are fixed in size. For visual use, brightness will, of course, vary depending on what eyepiece you use (ie, what magnification), but f/5 is pretty fast (bright) and will allow you to see and recognize many deep-sky objects such as galaxies and nebulae. You may even need to buy a filter or block off some aperature to view the moon without discomfort (I use a variable polarizing filter).

    A Newt gives good flexibility - it allows you to view dim objects, but also allows, with a Barlow and higher power eyepiece, great views of planets and the moon.
     
  20. Aug 10, 2007 #19
    Thanks Russ. you have been helping me with all my scope related questions. My biggest problem is that I just hate to do something twice. I rather spend a decent amount of money once.

    What is your opinion on the 8" EQ in post #1? I know you were the one who got me looking at Orions. I notice that Meade scopes of the same aperture ran higher in cost. This struck me as odd after the experience that had with the other scope I bought from them....I guess it is just a "first impressions" thing.

    From what I hear, Meade actually makes a quality scope. Has that been your experience? Was it just because I bought the cheapest one they had?
     
  21. Aug 11, 2007 #20

    Chronos

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    Someday you will be answering that question here.
     
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