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Thread: ultima 2x

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    Question ultima 2x



    Hi everyone
    Just found out I am getting a 2x ultima barlow for Christmas (ssh secret lol) from my wife and although I am over the moon, pardon the pun, I was wondering how the ultima compares to eyepieces of the same value and how much of an improvement visually will there be from my ordinary kit barlow.
    Thank you.
    Aidan.
    Celestron CPC 800 gps xlt.
    ZWO ASI290MC.
    ZWO ASI120MC.
    IS DBK 618.
    P Astro ADC
    Various Eyepieces and Barlows.

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    It will be way better than your kit barlow. I have one, tbf it also depends ( to a degree ) on the EP as well. I love using mine with a 25mm E-Lux EP.

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    Thanks pete
    A 25mm or maybe 20mm E-Lux, I don`t have a 10mm eyepiece so a 20mm would take my scope to close to max power or 400x, or am I wrong about that?
    Thanks
    Aidan.
    Celestron CPC 800 gps xlt.
    ZWO ASI290MC.
    ZWO ASI120MC.
    IS DBK 618.
    P Astro ADC
    Various Eyepieces and Barlows.

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    Quote Originally Posted by astroado View Post
    Thanks pete
    A 25mm or maybe 20mm E-Lux, I don`t have a 10mm eyepiece so a 20mm would take my scope to close to max power or 400x, or am I wrong about that?
    Thanks
    I think that's an 8 inch, F/10 scope. If not, you can substitute the right numbers.

    The aperture is 200 mm and the fl is 2000 mm. So a 10 mm ep will give you 200x. A 10 mm plus barlow will be equivalent to a 5 mm and give you 400x.

    But keep in mind that anything over 300x will be pretty fuzzy. The anology I use is looking at a newpaper photo with a magnifying glass. It gets bigger, but there isn't any more detail. The diffraction limit kicks in at 200x for an 8 inch scope.

    If I were buying an ep for that scope, it would be about 15 mm with an eye relief of 20 mm. That would give 266x with the barlow.

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    Thanks Ken
    Sorry about the wrong numbers, yes its an 8 inch f 10 scope, but I thought I could use a 7mm eyepiece or a 14mm with barlow to give me around 360x, as I have a 14mm eyepiece, you say this is too powerful, so would it be worth getting a 15mm when I have a 14mm and a 17mm and just use them without the barlow and keep the barlow for the 40mm E-Lux that came with the scope. Pretty confusing all this.
    Thanks.
    Aidan.
    Celestron CPC 800 gps xlt.
    ZWO ASI290MC.
    ZWO ASI120MC.
    IS DBK 618.
    P Astro ADC
    Various Eyepieces and Barlows.

  8. #6
    kencrowder's Avatar
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    Quote Originally Posted by astroado View Post
    Thanks Ken
    Sorry about the wrong numbers, yes its an 8 inch f 10 scope, but I thought I could use a 7mm eyepiece or a 14mm with barlow to give me around 360x, as I have a 14mm eyepiece, you say this is too powerful, so would it be worth getting a 15mm when I have a 14mm and a 17mm and just use them without the barlow and keep the barlow for the 40mm E-Lux that came with the scope. Pretty confusing all this.
    Thanks.
    Now you're getting into personal preference questions and only you know what you will want to do. The rule of thumb is that if you have to ask, you haven't used the scope enough.

    Your fl is 2000 mm. A 7 mm ep will give 285x. That's going to give you as much detail as any ep with a shorter fl. You can also get that with a 14 mm and a 2x barlow.

    A plossl, which is what usually comes with the scope, has limited eye relief which is proportional to the ep fl. Thus a 7 mm plossl will only have about a 5 mm eye relief. Eye relief is the distance your eye must be from the lens.

    A 14 mm plossl will have about 10 mm of eye relief and the barlow will keep that the same while giving the 285x.

    I like a 15 mm ep super plossl. It gives me 133x with a half degree FOV and 20 mm eye relief. I use that for searching. A barlow would double that magnification, but I seldom choose to do it. The barlow also cuts the FOV in half.

    I also have a 5 mm with 20 mm eye relief. It weighs a pound. I use it for collimation and on the rare occasion when I'm trying to separate something like Neptune from the stars. The planet is a slightly larger disk than the stars at 400x.

    Keep in mind that most amatures will spend most of their time at low magnification. You must find out what you enjoy spending your time doing. That's where you want your best ep.

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    Default

    Thanks kencrowder
    Great reply, yes I too view at low magnification and it`s true I have not used the scope anywhere near enough due to work commitments and weather of course. I have only had the opportunity to use my scope twelve times in three and a half months not anywhere near enough, the nights I work are almost always perfect for viewing and rubbish when I am off but having said that, I appreciate the times I spend under the stars far more when the weather is fine because of the limited time I get to spend at the scope.
    Thanks again
    Aidan.
    Celestron CPC 800 gps xlt.
    ZWO ASI290MC.
    ZWO ASI120MC.
    IS DBK 618.
    P Astro ADC
    Various Eyepieces and Barlows.

 

 

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