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Thread: GSO 1.25" 2.5x Apochromatic Barlow?

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    Default GSO 1.25" 2.5x Apochromatic Barlow?



    I am looking for a lightweight inexpensive barlow to take on trips.

    Any feedback on GSO 1.25" 2.5x Apochromatic Barlow?

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    Default Re: GSO 1.25" 2.5x Apochromatic Barlow?

    It seems to have a fair following from what I have read, unfortunately I have not used one so no first hand report
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    Default Re: GSO 1.25" 2.5x Apochromatic Barlow?

    Most of feedback I see is for 2" 2x version.

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    Default Re: GSO 1.25" 2.5x Apochromatic Barlow?

    There are a few on CN and stargazers lounge from a year or two ago. Not the most common f/l
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    Default Re: GSO 1.25" 2.5x Apochromatic Barlow?

    I read, somewhere recently, that the terms "achromatic" and "apochromatic" when applied to barlows is nothing more than a marketing ploy. The individual went on to say that an achromatic barlow does not introduce false colour on its own.

    I got the 2x and 3x Antares a while back, and couldn't be happier with their performance...

    Antares 1.25" 2x Barlow Lens with Twist-Lock Adapter and T-Thread # UB2STL

    The Antares 3x is out of stock, as is the 1.5x and 5x.

    I witnessed the first perfect star-test of my 4" f/8 apochromat with the 2x; with the 3x, a snap-to focus with a Newtonian and an average ocular. Mine, however, are the models immediately preceding those, and without the twist-lock feature.

    Of course, the GSO is a 2.5x, and perhaps you have an intended purpose for that specific multiplier. In addition, GSO's optics have received very good reviews overall.
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    Default Re: GSO 1.25" 2.5x Apochromatic Barlow?

    Hello BZ,

    I can already see a Barlow in your equipment signature.
    What's the reason to have 1 more Barlow, besides less weight?

    I am not a particular friend of the Barlows.
    The reason for my dislike is:
    Mounting a Barlow on an EP you can blow up the object viewed, but you can't improve the modulation transfer
    - in another words, the detail viewed is blown up into a more comfortable zone of your observing eye,
    but the light and the contrast is reduced, if compared with the view through the EP without a Barlow.

    Otherwise, the laws governing the properties of the modulation transfer function would become violated.

    Should these lines save you money not buying a Barlow, then donate something for a good purpose, please.

    Best,

    JG
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    Default Re: GSO 1.25" 2.5x Apochromatic Barlow?

    Hi JG,
    Generally, I am not big fan of barlows. However, I do like performance of TV 2x barlow I have, and enjoy using it on occasion, mainly with TV Plossls.

    I'd like to add one to my travel set, which would let me pack fewer EPs. It was either that or getting cheap zoom EP. I figured barlow would be lesser of two evils .

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    Default Re: GSO 1.25" 2.5x Apochromatic Barlow?

    I have the TS Optics version of this. It is very good quality for what it costs. It is light and mine has no undercut. There is no thread for filters and the Barlow element cannot be removed. It is just under 100 grammes in weight, 75mm long with a clear aperture of 22.4mm.

    TS mine.jpg

    Some people believe it gives 2.25x rather than 2.5x and I've suspected that for a long time. Whether it's a true apochromatic or not is also debatable, it seems like an apochromatic in use. I recommend it.
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    Default Re: GSO 1.25" 2.5x Apochromatic Barlow?

    I have the TS Optics version of this. It is very good quality for what it costs. It is light and mine has no undercut. There is no thread for filters and the Barlow element cannot be removed. It is just under 100 grammes in weight, 75mm long with a clear aperture of 22.4mm.

    TS mine.jpg

    Some people believe it gives 2.25x rather than 2.5x and I've suspected that for a long time. Whether it's a true apochromatic or not is also debatable, it seems like an apochromatic in use. I recommend it.
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    Default Re: GSO 1.25" 2.5x Apochromatic Barlow?

    Thanks Shorty Barlow.

    I have had my eyes on this TS shorty APO Barlow, but finally decided to take the Baader Q-Turret Barlow, which is an air-spaced triplet with more light throughput, and with the removable lens, and extremely lightweight.
    Not yet tested, but it might come handy for some close binaries pulling them apart into a more comfortable range of magnifications. The price has been acceptable to give it a chance.
    I don't intent to take it for the planets or Moon, see my reasons as above in post #6.

    Best,

    JG
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