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  1. #1
    Roger Thoms's Avatar
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    iCelcius temperature probe?

    I posed this question over on LFPF and thought I'd ask here too. Has anyone tried the iCelcius temperature probe for the iPad/iPhone? Just wondering if they are any good before I plunk down the money for one.

    Roger

  2. #2
    Lee L's Avatar
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    Accuracy +/- 1C, so 20C could be anywhere from 19C to 21C. That's a range of 3.6F. Not what I'd choose to standardize on for darkroom work if that's what you're thinking. Is the probe waterproof and chemical resistant?

    But if you want "stunning graphs" and something more "intuitive" than a standard thermometer interface...

    Lee

  3. #3
    RH Designs's Avatar
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    You'd be better off with an ordinary digital thermometer, which would be cheaper and at least as accurate. And if you dropped it in your developer tray it would be less of a disaster! Don't confuse accuracy with consistency by the way, most digital thermometers are only accurate to +/- 1 degree C but if calibrated to a master mercury or similar device will maintain that calibration very well, usually to within +/- 0.2 C or better.
    Regards,
    Richard.

    RH Designs - My Photography

  4. #4
    RalphLambrecht's Avatar
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    Richard is right. Thermometer accuracy is not as important as its precision. You can live with a thermometer that is within +/- 1C of the target value (accuracy), but when measuring a specific medium several times, you want those measurements to be as close together as possible (precision).
    Last edited by RalphLambrecht; 05-29-2011 at 11:15 AM. Click to view previous post history.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  5. #5
    Lee L's Avatar
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    Yes, I should have mentioned the accuracy-consistency-precision issue. I don't know if the item for sale is calibratable in software. That would be a nice touch. In the end we don't know how the iCelsius sensor is implemented, what sensor (and specs) it uses, or how good the software is. But they don't claim better accuracy than I mentioned in my earlier post. I'd make my own calibrated version for the same or less money.

    With many devices, like the LM34/35/36/37, the grading varies, with the more accurate versions selling for over US$8 and the lower accuracy versions for US$2. I doubt that the iCelsius uses a higher spec sensor at its price. However with these devices a simple offset variable will align them correctly to the scale, and then they are all spec'd to be linear within 0.5F across their full scales, from -50 to +300F in the case of the LM34. Again, I'd suspect that's not done very well, if at all, in a hardware/software package at this price point, and given the accuracy claims.

    Richard and Ralph are correct on all points, including the digital thermometer being a better value.

    Lee

  6. #6
    Roger Thoms's Avatar
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    I appreciate all the good advice from everyone, looks like a dedicated digital thermometer is the way to go. Any suggestions on a good one, there seems to be hundreds of different model available. I have no clue as to who make quality verses junk.

    Roger

  7. #7
    RH Designs's Avatar
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    Quote Originally Posted by Roger Thoms View Post
    looks like a dedicated digital thermometer is the way to go. Any suggestions on a good one
    I couldn't possibly comment
    Regards,
    Richard.

    RH Designs - My Photography

  8. #8
    Richard Lee's Avatar
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    Quote Originally Posted by Roger Thoms View Post
    ...looks like a dedicated digital thermometer is the way to go. Any suggestions on a good one..?
    Roger
    Roger,

    If lightning-fast delivery isn't a priority, then I would thoroughly recommend these.

    At this price, you could (as I did), purchase a spare or two. Cheap as chips and hugely reliable. Supplied with a battery as well.

    Richard

  9. #9
    Lee L's Avatar
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    Quote Originally Posted by RH Designs View Post
    I couldn't possibly comment
    ...because Richard is an advertiser here, and under the rules can't post his own items for sale in the forums. I'm under no such restrictions, so I can tell you that Richard sells this:

    http://www.rhdesigns.co.uk/darkroom/...ermometer.html

    And I expect that means he's found it highly suitable. I don't own one of these, but have something similar available locally in the US. I do use his Stop Clock Pro, which leads me to have great respect for his engineering and design expertise.

    Lee

  10. #10
    RalphLambrecht's Avatar
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    Quote Originally Posted by Richard Lee View Post
    Roger,

    If lightning-fast delivery isn't a priority, then I would thoroughly recommend these.

    At this price, you could (as I did), purchase a spare or two. Cheap as chips and hugely reliable. Supplied with a battery as well.

    Richard
    For that price, there must be something wrong with it.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

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