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Thread: Hygrometer accuracy

  1. #1

    Default Hygrometer accuracy

    Hi,i have been using the Aipo 48EX dry cabinet with digital readings.
    i set it to 44% humidity and it usually hovers between 44-45%.
    recently i bought a standalone Hygrometer.
    i placed it in my drycabinet for 1 day and it hovers between 56-58%.
    both readings doesn't tally and the difference is quite huge.
    anybody can advise on which should be the correct reading?
    thank you.


    http://flic.kr/p/bfgA3t
    Last edited by Turbonetics; 19th January 2012 at 07:33 PM.

  2. #2

    Default Re: Hygrometer accuracy

    the only way to find out which measurement is correct , is, to get ( or borrow) a calibrated hygrometer.
    However, please make sure both measure the same , for example, does one of them have a temperature compensation ?

  3. #3
    Member Turboredbean's Avatar
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    Default Re: Hygrometer accuracy

    Mate, Do the test (salt method) on your Stand Alone Hygrometer, then adjust accordingly ( + or -) on your Aipo. There is a lot of visual for these kind of stuff in youtube, I provided one for you.

    Calibrating a Digital Hygrometer - YouTube
    Canon 550D /18-135/50 1.8/75-300 USM III/10-22/70-200 f2.8L IS II/

  4. #4

    Default Re: Hygrometer accuracy

    Quote Originally Posted by Turboredbean View Post
    Mate, Do the test (salt method) on your Stand Alone Hygrometer, then adjust accordingly ( + or -) on your Aipo. There is a lot of visual for these kind of stuff in youtube, I provided one for you.

    Calibrating a Digital Hygrometer - YouTube
    thanks for the video.

  5. #5

    Default Re: Hygrometer accuracy

    i did the salt test and my standalone hygrometer shows 75%.
    can i confirm that my dry cabinet hygrometer is not accurate?

  6. #6

    Default

    Betweent 45-55% is ok setting as long as fungus cant thrive. Not sure if it so necessary to be so military precised? I set my dry cab at 50%.

  7. #7
    Moderator Octarine's Avatar
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    Default Re: Hygrometer accuracy

    Quote Originally Posted by Turbonetics View Post
    i did the salt test and my standalone hygrometer shows 75%.
    can i confirm that my dry cabinet hygrometer is not accurate?
    You ask us whether something in your dry cabinet is not working correctly? Your test shows that your stand alone hygrometer works well, that's all what your test shows. Everything else is assumption. Use the stand alone device then.
    EOS

  8. #8

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    Quote Originally Posted by Octarine
    You ask us whether something in your dry cabinet is not working correctly? Your test shows that your stand alone hygrometer works well, that's all what your test shows. Everything else is assumption. Use the stand alone device then.
    it does suggest that the one in dry cab is nt accurate, but perhaps shld tk out n test n calibrate?
    Alpha
    Want to get back to photography

  9. #9
    Moderator Octarine's Avatar
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    Default Re: Hygrometer accuracy

    Quote Originally Posted by Prince Photogenic View Post
    it does suggest that the one in dry cab is nt accurate, but perhaps shld tk out n test n calibrate?
    Your decision Curious as I am I would try it. But these cheap mass products my not be prepared for being calibrated, you just need to know about the offset.
    EOS

  10. #10

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    Quote Originally Posted by Octarine
    Your decision Curious as I am I would try it. But these cheap mass products my not be prepared for being calibrated, you just need to know about the offset.
    oh.. haha.. anyway if it's below 45% i'm nt too worried since the other thread showed that lub n plastic wun dry..
    Alpha
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  11. #11
    Moderator ed9119's Avatar
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    Default Re: Hygrometer accuracy

    Quote Originally Posted by Turbonetics View Post
    i did the salt test and my standalone hygrometer shows 75%.
    can i confirm that my dry cabinet hygrometer is not accurate?
    .... you could do that test with a few other sodium variants with different hygroscopic values ..... then, can really confirm
    shaddap and just shoot .... up close
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  12. #12

    Default Re: Hygrometer accuracy

    I just want to say that if you set your cabinet to 45-50% then you are cutting it close. I had a lens with fungus in cabinet with the meter showing 50%. I think the meter had gotten slightly out of calibration over time.
    Now I set one cabinet to 35% and another to about 40%. And I also remove the front lens caps.

  13. #13

    Default Re: Hygrometer accuracy

    I have 2 dry cabinets and bought 4 external hygrometers recently. They all show about the same readings (about +15% more than dry cabi readings).
    I always set my dry cabinets to 45% and all my external hygrometers shows about 60%

    My question:
    The relative humidity in sg is above 80% so will there be problem if I do the salt test? (unfortunately I cannot afford air-con at home)
    I have one in a ziploc bag now... waiting for inspection tomorrow.
    Last edited by NicePic; 8th March 2012 at 04:38 AM.

  14. #14

    Default Re: Hygrometer accuracy

    Quote Originally Posted by ed9119 View Post
    .... you could do that test with a few other sodium variants with different hygroscopic values ..... then, can really confirm
    Correct me if I'm wrong, I believe pure sodium chloride will do, it's based on lab tests that shows at different temperatures, sodium chloride slug maintains at near 75% RH.
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  15. #15

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    Quote Originally Posted by Turbonetics
    Hi,i have been using the Aipo 48EX dry cabinet with digital readings.
    i set it to 44% humidity and it usually hovers between 44-45%.
    recently i bought a standalone Hygrometer.
    i placed it in my drycabinet for 1 day and it hovers between 56-58%.
    both readings doesn't tally and the difference is quite huge.
    anybody can advise on which should be the correct reading?
    thank you.

    http://flic.kr/p/bfgA3t
    Hi, I have the same model as you and the standalone hydrometer shows about the same value as yours when the cabinet meter set to 44%.
    I did a salt test calibration with my analogue hydrometer(the digital hydrometer seems pretty accurate) and I now have to set the cabinet meter to 30% to achieve the RH45-46% reading from the 2 hydrometers in my cabinet
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