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How do you deal with dew on your telescope / Bino lenses?

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  • 26-03-2005 11:30am
    #1
    hamster
    Registered Users Posts: 1,766 ✭✭✭


    Well, this issue is coming more and more to the fore. How do you deal with it? I had 2 different situations where it occurred:

    1. Last week I had them outside from 3pm-11pm and dew formed on the lenses despite the binos already adjusted to the surrounding temperature.

    2. Last night, brought them out and in every 10-15 mins before dew built up.

    Seems like you need either a mini-fan in front of lenses to keep the dew away or somehow get the temperature of the lenses above the dew-point... or hope for a windy night. Is this an issue with you?


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    #2
    hamster
    Registered Users Posts: 1,766 ✭✭✭hamster


    hamster wrote:
    Well, this issue is coming more and more to the fore. How do you deal with dew on your lenses?

    Well tonight I brought the binos out but left on the cover caps on for 10-20 mins before use and there was very little dew on them tonight after extending viewing. Seems to do the trick.


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    #3
    albertw
    Closed Accounts Posts: 395 ✭✭albertw


    For the scope with a 10" corrector plate I need a dew shield. A converted camping mat does the job quite nicley!


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    #4
    hamster
    Registered Users Posts: 1,766 ✭✭✭hamster


    albertw wrote:
    For the scope with a 10" corrector plate I need a dew shield. A converted camping mat does the job quite nicley!

    albertw,

    Do you leave it on for awhile outside to get to the same temperature before viewing? And while viewing do you put the plate back on while saying grabbing a quick 2min snack?


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    #5
    albertw
    Closed Accounts Posts: 395 ✭✭albertw


    Hi,
    hamster wrote:
    Do you leave it on for awhile outside to get to the same temperature before viewing? And while viewing do you put the plate back on while saying grabbing a quick 2min snack?

    Yep, my scope takes litereally a couple of hours to cool down properly. I still observe while its cooling down but there is a very noticable improvement in images when it cooled.

    I dont bother putting the cover back on, the dew shield usually does a good enough job of keeping the dew off so I don't bother.

    Cheers,
    ~Al


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    #6
    Orion
    Closed Accounts Posts: 12,807 ✭✭✭✭Orion


    albertw wrote:
    I dont bother putting the cover back on, the dew shield usually does a good enough job of keeping the dew off so I don't bother.
    Cheers,
    ~Al

    what's a dew shield? :confused:


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    #7
    albertw
    Closed Accounts Posts: 395 ✭✭albertw


    Macros42 wrote:
    what's a dew shield?

    These things: http://www.greenwich-observatory.co.uk/acatalog/Dew_Shields.html

    Or in my case a camping mat rolled up and slid onto the top of the scope :-)
    http://www.netsoc.ucd.ie/~albertw/astro/images/lxd55sandymount.jpg


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