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    Default Barlow lens GSO 5x?



    For planetary (astrophotography) purposes, I want to buy a 5x Barlow lens. AFAIK, this Barlow is an apochromatic one. There is somebody who can tell me about the quality of this lens? Maybe, if possible, compared with other 5x lenses (Powermate, for example)? Thanks in advance.
    binoculars: Tech Tactical Gear Phantom M1050, MLC 8x30, Auriol 10x50 + 10-30x60
    optics: SW Newtonian 200/1000, SW Maksutov-Cassegrain 127/1500; Powermate 2.5x, Vixen APO Deluxe 2x Barlow
    mounts: HEQ5 Synscan GoTo & Giro 2 Deluxe
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  2. #2
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    Default

    With few exceptions, I have found that barlows don't degrade the image perceptably, and are preferable to short eyepieces. I need 20mm of eye relief.

    I have some nice comfortable EPs in these focal lengths; 20,25,26,30,32. I have 2 3x barlows, (a TelVue and a cheap plastic barreled one) and the cell from a 2x barlow I can drop into the tube of the 3x barlows, making them into 5x barlows.

    $50 plus shipping to Europe isn't a big investment. If you have good EPs to back it up, I would recommend going that route.

    More information here: Barlow information?
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  3. #3
    ursamajor's Avatar
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    Other opinions?
    binoculars: Tech Tactical Gear Phantom M1050, MLC 8x30, Auriol 10x50 + 10-30x60
    optics: SW Newtonian 200/1000, SW Maksutov-Cassegrain 127/1500; Powermate 2.5x, Vixen APO Deluxe 2x Barlow
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    Default

    I guess I've never seen the reason for a barlow over 2x. Actually, I don't use barlows at all. I prefer to have separate eyepieces. I used to have a 2x TV powermate, but sold it as I just found I don't care for using them. To me it's just another piece I had to fiddle with, and the less glass I can put in the light path the better. But that's just my personal opinion.
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  5. #5
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    Default

    Quote Originally Posted by ursamajor View Post
    For planetary (astrophotography) purposes, I want to buy a 5x Barlow lens.
    That's the reason. For visual purposes I don't use Barlow too.

    So, can anyone respond to my answer, please? Is the 5x GSO a good Barlow from the quality point of vue? Or, better, can anyone compare it to 5x Powermate? Thanks in advance.
    binoculars: Tech Tactical Gear Phantom M1050, MLC 8x30, Auriol 10x50 + 10-30x60
    optics: SW Newtonian 200/1000, SW Maksutov-Cassegrain 127/1500; Powermate 2.5x, Vixen APO Deluxe 2x Barlow
    mounts: HEQ5 Synscan GoTo & Giro 2 Deluxe
    cameras: Canon EOS 550D + 18-55 + 50/f1.8 & modified Microsoft Lifecam Studio + 6000HD

  6. #6
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    Default

    I would disagree with Pierre- I have several 2x and 1---- 3x barlows. I prefer viewing with an eyepiece (without) using a barlow.

    The barlows were purchased a long time ago before my eyepiece collection expanded. So-- I am a proponent of SLOWLY increasing your eyepiece collection until you have a nice spread of magnification with individual eyepieces that you enjoy looking through.

    Nothing wrong with buying a 2x barlow for starters while you slowly buy additional eyepieces, as this will double your current collection of eyepieces.

    Anyway-- that's what I did, your mileage may vary!
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  7. #7
    ursamajor's Avatar
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    Default

    OK, my friends. Thanks for the help.
    I bought, then, the GSO 5x. I'm very happy with it. A good "high magnification" Barlow at a low price. But full luck there isn't on Earth.
    So, visually, the GSO 5x is extraordinary, over the expectancies.
    But using my Canon 550D, I saw a little round spot in the center of my pictures. The "issue" is present only when I use the dSLR for focal pictures. Afocal, all is OK. I took a picture with a small compact (Fujifilm F40FD) at 500x (1000 mm focal, with 10 mm eyepiece and GSO5x) and the issue isn't there.
    I attached two pictures taken through my telescope (203/1000 Black Diamond), one focally (Canon 550D + GSO5x), other afocally (compact + 10 mm eyepiece + GSO5x). I corrected the contrast, so the issue is very much amplified. Can anyone tell me why the issue is manifesting? Thanks in advance.

    PS: Please, ignore the ad-notations on the focal picture. It's about the dirty sensor and the size of Jupiter at 500x.
    Attached Images Attached Images
    binoculars: Tech Tactical Gear Phantom M1050, MLC 8x30, Auriol 10x50 + 10-30x60
    optics: SW Newtonian 200/1000, SW Maksutov-Cassegrain 127/1500; Powermate 2.5x, Vixen APO Deluxe 2x Barlow
    mounts: HEQ5 Synscan GoTo & Giro 2 Deluxe
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  8. #8
    ursamajor's Avatar
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    I found this article and I'm sure that this is the explanation of the phenomenon. It's a sensor reflection. I already checked, in the dark the issue isn't manifested.
    binoculars: Tech Tactical Gear Phantom M1050, MLC 8x30, Auriol 10x50 + 10-30x60
    optics: SW Newtonian 200/1000, SW Maksutov-Cassegrain 127/1500; Powermate 2.5x, Vixen APO Deluxe 2x Barlow
    mounts: HEQ5 Synscan GoTo & Giro 2 Deluxe
    cameras: Canon EOS 550D + 18-55 + 50/f1.8 & modified Microsoft Lifecam Studio + 6000HD

 

 

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