What magnification is required to see detail on Mars / other local bodies?

  • I have a 125mm Jones Bird newtonian telescope (very shoddy) with 6x lens (2× + 3×) essentially we were able to see a very small O (yeah that's to scale) with varied shades of red.

    Is Mars far away from earth right now relative to the average distance or is it just my telescope not powerful enough?

    If I wanted to seriously have a chance at picking up significant features on Mars or perhaps pickup the rings of saturn or the red spot of jupiter, whats the minimum setup that I am going to need?

    This setup would run me around 3,000 dollars:

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    Its named...

    Celestron CPC 1100 StarBright XLT GPS Schmidt-Cassegrain 2800mm Telescope with Tripo... https://www.amazon.com/dp/B000ARFND2/ref=cm_sw_r_sms_c_api_x7mSBb39EAS9H

    Would this be overkill? For $3,000 is this one of the better choices for local planetary observation?

  • You have several questions here:

    1. Mars is relatively close to Earth right now (October 2018) - about 90 million km.

    2. Is your telescope powerful enough for you to see detail on Mars? From what you have said, it's difficult to tell. You say you have magnification of 6x. This is almost certainly wrong. If you state the focal lengths of your telescope and its eyepieces we can work out the correct magnification available. To see much detail on Mars you would need in excess of 100x magnification (same for Saturn, less for Jupiter), and ideally a lot more. Your scope should be able to manage 100x. However the Jones Bird design is known to be difficult to align (collimate) properly, so even with that magnification, you may just see a blur. How much detail you can see will also be heavily affected by the state of the atmosphere - ideally you need a night when the air is calm. Sometimes a slight mist can indicate a steady atmosphere.

    3. Would the CPC 1100 be overkill etc? This is much more opinion based, but in short, yes - for a beginner anyway. For an experienced observer, the answer is much more nuanced, and I'm not going to go into any of that. The scope is generally regarded as pretty good for what it is.

    Ah- fair enough. If it were a beginner looking to become advanced? I know basic orbital mechanics and Im trying to learn to track from observational frames but know nothing of telescopes. I figured i could get the scope then figure a lot more of it out through experience. Would you recommend anything else from experience over that for the price?

    Also thanks for the response. I know its a poor question- but I am severely interested in the hobby after even my first experience and want to get a jumpstart for my buck haha.

    Checked the relative distance on new horizons. 9.8/15 so isnt the next best viewing time around september next year?

    If you're asking about Mars, it comes to opposition approximately every 26 months, and therefore it is closest to the Earth every 26 months. September 2019 will not be a good time to look at Mars. Maybe September 2020.

    Ahhhh I needed to be looking for when the deldot goes from negative to 0, not from positive to 0. 2020-Oct-07 00:00 seems to be the next closest appearance from my coordinates, you were totally correct :).

  • It's a lot easier to see detail on Jupiter, or pick out the rings of Saturn than it is on Mars.

    Although Mars is closer to us, Jupiter and Saturn are a LOT bigger - and so appear larger. And because Mars is closer to us, its apparent size changes a lot berween closest approach (opposition) and when it's further away. When it's close to opposition, it's significantly larger than when its further away; From memory, I think there's a least a 3X difference in apparent size.

    Even when it's close, it's still pretty small. And unlike Jupiter and Saturn, where the details are easy to see, Mars tends to need more patience and practice. Look at jupiter or Saturn and the details are immediately obvious. Look at Mars, and you really want to keep looking for several minutes. Most of the time you may not see much, but every so often you'll get a bit of good seeing and be able to glimpse some detail. (planets are also best seen when higher above the horizon; when it's low, you're looking through much more atmospheric crud and turbulence).

    You should certainly be able to see the rihgs of Saturn and details on Jupiter with your current scope - but even at high magnifications the planets are still going to be small. We're spoilt by the full page images we see in magazine photos - through the eyepiece things aren't going to be anything like that big. Expect to see a small planet in the middle of the eyepiece - your O is typical :) .it may not be big, but can be nicely detailed.

    A bigger aperture scope has more resolution, allowing you to see finer details, and allows more magnification before you get to the point where increasing magnification just makes things bigger and blurrier without showing more detail.

    Typical maximum everyday magnification is usually around your aperture in mm, which you get with an eyepiece focal length equal to your scopes f-ratio (so 8mm for an f8 scope, and so on).

    With very good seeing (steady atmosphere), which can be rare, you can go to around twice the magnification. This is what manufacturers usually quote as the maximum magnification; what they don't say is that it requires near perfect conditions which may only happen a few times a year.

    I have a N11GPS, the model before the CPCs. Views are nice, and it's a good light bucket but it's a bulky and heavy beast that's a pain to move any great distance. Not a problem if you can leave it set up in an observatory, but if you have to take it in and out then you might want to consider some sort of trolley or balance better views with portability - I think the 8" fork mounted SCTS are probably the sweet spot between performance and portability. I can lift an 8" on its tripod, but I have to move the 11" OTA+Mount and tripod separately.

    Although the specs quote 661x as the maximum magnification, I've found that to be optimistic in practice - while I can use a 12mm eyepiece all the time (233x) It's very rare that I've been able to use an 8mm (350x) and I don't remember ever being able to use a 5mm eyepiece (576x). I think the quoted 661x is being wildly optimistic, at least for the seeing conditions where I am, but those can vary significantly with location. Just remember that a lot of the time, the atmosphere will limit how much magnification you can use.

    But also remember, that for a lot of deep sky objects, it's more about light gathering than it is about high magnifications. Many objects work better at lower magnifications.

    (By the way, magnification = focal length of scope / focal length of eyepiece, so a 10 mm eyepiece in a 700mm focal length scope will give you 700/10 = 70x magnification. Adding a 2x barlow doubles that, a 3x triples it, and using both multiplies by six - which is likely to be way over the useful magnification for the scope and won't do wonders for the image quality...)

    Wellp, that last sentence with the mathematics behind magnification definitely helps. But basically, for Mars you need to calculate when it's at is closest, and highest in the sky? Thanks for the explanations on a lot of this stuff, super helpful to just hear someone else talk about what they did and know/have experience with.

    Yes, that's basically it. Since the geometry changes, some oppositions will have Mars reaching higher above the horizion than others. You might want to have a look at the free planetarium program called "Stellarium" - it'll show you what things look like now, or at any other dates.

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Content dated before 7/24/2021 11:53 AM

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