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  1. #11
    tiberiustibz's Avatar
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    Say I want to acquire a thermometer which is "accurate" to .1 degrees, not precise to .1 degree and accurate to 1 degree (useless specificity???) Where might I do that?
    --Nicholas Andre

  2. #12

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    Quote Originally Posted by Reinhold View Post
    Those impressive LED numbers on that hi-falootin elektronik gizmo are only a read-out from a collection of parts put together by monkeys.
    We are not monkeys. We are apes.

    Side note:
    Q: Are we not men?

    A: Are are DeVo!
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!

  3. #13
    greybeard's Avatar
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    Say I want to acquire a thermometer which is "accurate" to .1 degrees, not precise to .1 degree and accurate to 1 degree (useless specificity???) Where might I do that?

    The closest practical approach is probably to acquire a Kodak Process Thermometer. They were made for both black-and-white and color work (the latter has its scale centered at 75F, as opposed to 68F, if I remember correctly) and are about as reliable as you could ever need. The scale is expanded around the nominal processing temperature, and each thermometer was individually engraved so that the capillary bore diameter variations are unimportant.

    That having been said, for photographic work the precision is more important than the absolute accuracy, particularly if an etched-stem thermometer is being used as a check on a more convenient dial or digital thermometer. Column separation (which is easily detected) is about the only thing that can change the calibration of an etched-stem thermometer; the cheap aquarium thermometers and their ilk, which have the tube stuck to a pre-printed card, can have their accuracy destroyed by distortion of the card or the mounting.

    Realistically, you'd have to be doing pretty fancy sensitometric work to be concerned over even a half-degree variation in process temperature, given the effects of agitation, water quality, film-lot variation, and initial exposure.

  4. #14
    fotch's Avatar
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    I have 3 Kodak Process Thermometers, acquired in different years from different sources and they all agree to within a 1/4 degree F. I use one for checking any other thermometers I use. The dial type are the easiest to read but the least accurate in my experience.
    Items for sale or trade at www.Camera35.com

  5. #15
    greybeard's Avatar
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    The dial type are the easiest to read but the least accurate in my experience.

    Yep. Mine took a two- or three-degree jump a few years ago (it's hard to read to closer than that because the pointer is so wide) which was easily detectable in the highlights of Plus-X developed in HC-110. Once I had figured it out, I just work with the pointer in the "right" place for my personal processing method. But I check it against the Kodak thermometer before doing anything really important.

    I bought a dial-type thermometer for my son a few years ago, and found that it was off by more than five degrees at a nominal 68F! Needless to say, it went right back to the store, where for all I know it was later sold to someone else...

  6. #16
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    We are anlog photographers ...I try to keep it pretty analog. My thomometers seem to be pretty good and they are the alcohol ones.
    Helping to save analog photography one exposure at a time

  7. #17
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    Quote Originally Posted by bowzart View Post
    There are still problems with the ice water standard, if you are going to be picky. Use distilled water. Finding 0°C isn't the whole picture, either. For a full calibration, you'd need the freezing AND boiling points, since the range can be off as well, and for the boiling point, the barometric pressure would have to be accounted.
    Agreed! Use Distilled water if you really want to be right.
    And, yes, if you are measuring the boiling point of water in any capacity you need to account for altitude and barometric pressure. There is an on-line calculator for that if you like:

    http://www.csgnetwork.com/h2oboilcalc.html

    According to this calculator, at my altitude and pressure, water boils at 210.6 ºF. (I am at 730 ft. above sea level and the barometer reads 29.83 in.)

    Therefore, I might suggest to OP to retry his experiment and take the altitude and pressure into account.

  8. #18
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    I have the round dial thermometer and the recalibration instructions are as follows:

    Fill a tall glass with crushed ice.

    Immerse stem a minimum of 3 1/2" in the ice.

    Wait a minimum of 30 seconds and adjust nut on top of the stem so pointer reads 32 degrees F.

    When I first read this I thought they were talking about me when they mention to adjust the nut. I was thinking when all is done, can't ruin all this ice, lets get to the liquor cabinet! Orange juice!
    Bill Clark

  9. #19
    Bijesh's Avatar
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    Almost all thermometers show the wrong temperature. For B&W, it's enough that the thermometer gives the same reading for the same temperature every time. I've several thermometers and these are the readings at the same temperature:

    Mercury - 68
    Kodak Color - 67
    Dial 1 - 70
    Dial 2 - 69
    Dial 3 - 58 ?
    Dial 4 - 68
    Red Alcohol - 68
    Blue alcohol 1 - 65
    Blue alcohol 2 - 69

    The mercury thermometer is the standard and it reads 32 when immersed in crushed ice and I use it only to compare with the others.

  10. #20

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    Bill, you should have thown all the ice away except two of the cubes. You just have to refill more often if you have all that dang ice in there.

    Mike

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