Jeff Liebermann wrote:
On Tue, 29 May 2012 19:11:25 -0400, "Charles"
wrote:

http://www.harborfreight.com/non-con...ter-93983.html
Just posted as an aside. I am amazed at how well the cheap ones work.

My father one told me to beware of anything that is amazing, magical,
miraculous, etc. They rarely are.

I have one of those Centec pocket thermometers. It's great for
cooking. However, there's a problem or three. The beam width is
about 90 degrees making it very difficult to measure the temperature
of an object, without also including the temperature of the
surroundings. An upper limit of 110C means that won't work under the
hood of my car, or for measuring the temperature of my wood burner,
barbeque, or hibachi. There are better units for not much more and
that have a narrower beam width (none of which can seem to get the
laser to align with the measurement spot).

Using an IR thermometer for measuring air temperature is somewhat of a
problem. The air has a very low mass and therefore emits very little
IR light for the device to measure. A solid object that's in thermal
equalibrium with the air temperature will work, but only if it has the
preset 0.95 emissivity. Going outside and measuring the temperature
of various building walls, plants, planters, and dirt, I get wide
variations in readings. The wood planter seems to be the closest to
the air temperature.


You can hold up a piece of paper in front and measure air temp. You can
even tape a piece of paper on the front. Just stay out of sunlight.

Greg