On finding a cheap good usefull colour thermometer

Robert · Jul 5, 2003

You know the old saying. You can have it cheap,fast or good. Pick any two. Well with thermometers the same thing seems to be the issuse. The thing is to ignore the things labeled photographic and look else where. What is used in a similar temp range to something like E6? Why human beings are. Yup we tend to run around 38C. Sounds like E6 temps.

Today I picked up a digital thermometer. Cost me $11 at walmart because I wanted the one with both C and F. That's Canadian. It's accurate to within +/-0.2degrees F in the range of 93F to 107F. That's claimed accuracy not resolution. Turns out my digital thermometer is off by about 1.5degrees F. My adjustable dial one may be off by a little more. But then I didn't do the best job testing the dial thermometer. Long stem may have caused some problems.

Downside is it takes awhile to get a reading. Upside it should be great to set my adjustable dial thermometer or to take a reading of the water bath.

So it's good and cheap. It's not fast but you can't have everything.

lee · Jul 5, 2003

I have one I bought at Bed Bath and Beyond. Reads Cand f and is a probe type. Cost about 15 dollars there in the kitchen dept. And is water proof.

lee\c

Robert · Jul 6, 2003

my digital one is a kitchen one also. Turns out in the range of 95-100F it was off 1.5degrees. For cooking 1.5 degrees is more then good enough. OTOH the fever one I got should be more accurate and is cheaper to boot.

Ed Sukach · Jul 6, 2003

Robert said:
. It's accurate to within +/-0.2degrees F in the range of 93F to 107F. That's claimed accuracy not resolution. Turns out my digital thermometer is off by about 1.5degrees F. My adjustable dial one may be off by a little more. But then I didn't do the best job testing the dial thermometer. Long stem may have caused some problems.
.

If the advertised accuracy was +/- 0.2 degrees F, it should display a temperature of +/- 0.2 from the true value. Resolution would be the smallest division displayed (I would assume, with no additional information, 0.1 degree F. There are devices that will measure 0.01 degree F, but there are so many fators other than the instrument itself, that a lab environment becomes a necessity).

When you say this is "off" by 1.5 degrees F, what standard are you using for comparison? From the range, this sounds like it is a "medical thermometer" used for measuring body temperature - if those are inaccurate by 1.5 degrees F (from the true temperature), they are useless.

You speak about a "dial thermometer" - I would assume you mean one of those made by Weston (I have one with a Cibachrome logo) or others - a "dial on a stick" Those are easily calibrated by adjusting the nut holding the stem to the dial. I've calibrated mine aganst a Kodak Laboratory (mercury) Thermometer and it is reliable to one half degree F - or so (never trust the reading of any measuring device to a value less than the smallest division - the resolution).

BTW - What would you cook between 93 and 107 degrees F?

Flotsam · Jul 6, 2003

I'm interested in this thread too. I have a beautiful old stainless and glass Kodak process thermometer but I would rather use that as a standard to calibrate other, more rugged, less precious ones. I would be very interested in any suggestions for an accurate, easy to read, preferably inexpensive one that can be calibrated. I am only processing B&W now so I'm looking for something that covers the 70ºF range.

I have a Weston but it doesn't have a calibration nut behind the dial. It is old. Do the newer Westons have this adjusment? I once had a Beselar dial with this feature but it is long gone.

Neal

Ed Sukach · Jul 6, 2003

Flotsam said:
I'm interested in this thread too. I have a beautiful old stainless and glass Kodak process thermometer but I would rather use that as a standard to calibrate other, more rugged, less precious ones. I would be very interested in any suggestions for an accurate, easy to read, preferably inexpensive one that can be calibrated. I am only processing B&W now so I'm looking for something that covers the 70ºF range.
I have a Weston but it doesn't have a calibration nut behind the dial. It is old. Do the newer Westons have this adjusment? I once had a Beselar dial with this feature but it is long gone.
Neal

I would use the Kodak process thermemeter in a limited mode - only for calibrating others. I've broken too many glass-mercury thermometers as it is - ask me about using the old sling psychrometer for measuring humidity...

If you have one of the "dial" types without the adjusting nut, it must be an "old" one ... (or a really "el cheapo"). I can't remember seeing any of those - ever - and I started in Calibration some fifty years ago.

The "newer" dial thermometers are relatively inexpensive, reliable and durable ... and in my opinion totally adequate for ALL photographic purposes - including color - (see "Cibachrome logo"). Check to see that there is an adjusting nut before you buy one.

Robert · Jul 6, 2003

Ed Sukach said:
If the advertised accuracy was +/- 0.2 degrees F, it should display a temperature of +/- 0.2 from the true value. Resolution would be the smallest division displayed (I would assume, with no additional information, 0.1 degree F. There are devices that will measure 0.01 degree F, but there are so many fators other than the instrument itself, that a lab environment becomes a necessity).

When you say this is "off" by 1.5 degrees F, what standard are you using for comparison? From the range, this sounds like it is a "medical thermometer" used for measuring body temperature - if those are inaccurate by 1.5 degrees F (from the true temperature), they are useless.

You speak about a "dial thermometer" - I would assume you mean one of those made by Weston (I have one with a Cibachrome logo) or others - a "dial on a stick" Those are easily calibrated by adjusting the nut holding the stem to the dial. I've calibrated mine aganst a Kodak Laboratory (mercury) Thermometer and it is reliable to one half degree F - or so (never trust the reading of any measuring device to a value less than the smallest division - the resolution).

BTW - What would you cook between 93 and 107 degrees F?

No I'm using a fever thermometer to test the other two. It reads 0.1. The one that is off 1.5 is the kitchen digital. It's range is much wider then the fever thermometer. But the range I'm worried about is a pretty good match for the fever thermometer. Some one also mentioned that digital thermometers tend to show the same error all over thier range. If that's true then all I need to do is add 1.5 degrees.

The dial one is colour one made in Japan. The name doesn't stick in my head but I'm guessing it was made for various people under different labels. It's about 2+ inches and glows. A little too busy with all the 1/2 degree divisions.

On finding a cheap good usefull colour thermometer

Robert

lee

Robert

Ed Sukach

Flotsam

Ed Sukach

Robert

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