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Zennox Telescope 76 700 lens of track,worth to fix?

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  • 21-07-2015 2:15pm
    #1
    lifeandtimes
    Closed Accounts Posts: 2,021 ✭✭✭


    Hi Everyone,

    I'm thinking of purchasing a used Zennox Telescope 76 700, however the seller has advised that they tried to adjust the lens but accidentally set it off track.

    The price is fairly decent for it but I'm wondering is it worth buy and trying to fix the lens issue?

    Granted I'm no pro but i ma handy at fixing things.

    any advice appreciated


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    #2
    Seanie M
    Registered Users Posts: 1,795 ✭✭✭Seanie M


    Hi there,

    The Zennox series was a very cheap (meant to be affordable) reflector. 76mm is typical of small-sized reflectors, going all the way back to the late 70s when Tasco and others produced them en masse. In Ireland, Zennox recently came to availability through Aldi or Lidl (can't remember which).

    If the objective lens is out of alignment, then it can be repaired. I have done it before on my first telescope - coincidentally, a 76mm Tasco reflector (got it in 1990), and I'd know what to do. Unless you know someone who can do this for you, then if you do buy it, it'll be on your shoulders via trial and error to get it right on your own.

    Before you even think about buying it, I recommend you go view it in person to see the state of the mirror. Unfortunately, a common problem on low budget, small reflectors, is that the mirror coatings don't last a long time. In the hands of someone who didn't really know how to store or maintain it (let alone tampering with the objective and knock it out of alignment), then you will have other problems too.

    How much is the asking price?


    Seanie.


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    #3
    lifeandtimes
    Closed Accounts Posts: 2,021 ✭✭✭lifeandtimes


    Seanie M wrote: »
    Hi there,

    The Zennox series was a very cheap (meant to be affordable) reflector. 76mm is typical of small-sized reflectors, going all the way back to the late 70s when Tasco and others produced them en masse. In Ireland, Zennox recently came to availability through Aldi or Lidl (can't remember which).

    If the objective lens is out of alignment, then it can be repaired. I have done it before on my first telescope - coincidentally, a 76mm Tasco reflector (got it in 1990), and I'd know what to do. Unless you know someone who can do this for you, then if you do buy it, it'll be on your shoulders via trial and error to get it right on your own.

    Before you even think about buying it, I recommend you go view it in person to see the state of the mirror. Unfortunately, a common problem on low budget, small reflectors, is that the mirror coatings don't last a long time. In the hands of someone who didn't really know how to store or maintain it (let alone tampering with the objective and knock it out of alignment), then you will have other problems too.

    How much is the asking price?


    Seanie.

    Hi Seanie,

    Wow thanks for your very informative and helpful response.

    The asking price is €40 so not breaking the bank much, i haven't viewed the instrument yet but it looks in good in the pictures, not much wear and tear and the seller is more than happy to let it be seen before its purchased.

    Though as I'm a novice at this im not sure id be comfortable putting time and money into fixing it without getting a long return on the instrument.


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    #4
    Seanie M
    Registered Users Posts: 1,795 ✭✭✭Seanie M


    You're welcome!
    lifeandtimes wrote: »
    The asking price is €40 so not breaking the bank much...

    ... im not sure id be comfortable putting time and money into fixing it without getting a long return on the instrument.

    €40 is not much to shed on it. Collimation is what you will need to do to get it back in shape (if that's all it is). It probably comes with 3 eyepieces (25mm, 12.5mm and 9mm or 6mm, plus a 2X barlow perhaps). The only EPs you'll need with this scope will be the 25mm and 12.5mm. The Barlow and 9mm or 6mm EPs will be pretty much useless on such a small aperture scope.

    Collimation is easy IF you can get your hands on a laser collimator. The back of the mirror should have 3 small screws that, as long as the mirror is fully fixed in its cell (as flat as possible), can be individually adjusted to orientate the mirror in line with the laser, centering it. This increases the light gathering power, decreases the likelihood of colour (chromatic) aberration, and the kind of cloudy, fuzzy image seen through an uncollimated telescope.

    Where are you located?

    Seanie.


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