# Thread: Harbor Freight Laser Thermometer

1. ## Harbor Freight Laser Thermometer

Just got an email on this morning

http://www.harborfreight.com/cpi/cta...campaign=1210A

2. or this for pop off and case seal

http://www.harborfreight.com/cpi/cta...campaign=1210A

3. Originally Posted by seaobin
Non-Contact Laser Thermometer

What does this spec mean?
Distance to spot accuracy: 8 to 1

4. What is the distance to spot ratio?

D/S Ratio- Distance to Spot ratio refers to a very important feature of your infrared thermometer. This ratio is the size of the area being evaluated by the infrared thermometer as it relates to distance. In other words, the area being measured becomes larger as the distance increases. This has a profound impact on the accuracy or precision of the reading. If the target you are measuring is 6 inches in size, and your infrared thermometer has a D/S ratio of 8:1, than the maximum distance you can reliably measure the temperature of the target is 48 inches. Beyond this distance, not only is the target being measured, but whatever else falls within the "spot" is being measured as well. This means that if a very hot object is the target, and it is in cooler surroundings, than measurements taken beyond the maximum distance will include cooler elements, and lowering the "average" of what is in the "spot".

D/S Ratio X Target Size, or 8:1 X 6 = maximum measure distance of 48 inches.

As the target size decreases, or the distance to the target increases, a larger D/S Ratio becomes necessary. Using the same example above, and changing first the target size, and then the D/S ratio, you can see that this formula helps you decide the correct D/S ratio and therefore the Infrared Thermometer for your needs.

D/S Ratio X Target Size, or 8:1 X 2 = maximum measure distance of 16 inches.

D/S Ratio X Target Size, or 12:1 X 2 = maximum measure distance of 24 inches.
D/S Ratios vary greatly, so carefully compare this feature of IR Thermometers when comparison shopping. This ratio, and temperature range are the two biggest factors to consider when shopping for an Infrared Thermometer!

5. Thank you for the explanation.

The Harbor Freight description doesn't say 'distance to spot ratio', it says;

Distance to spot accuracy

Just another incorrect product description, or is this something different?

6. The Cheap Chinese dictionary that they used to translate the Chines specs, used the wrong words

7. Those non contact thermometers are cool, but ive had them give me some questionable readings on odd surfaces. Generally on really reflective or smooth surfaces it can be off.

On most anything else they work great if youre close. But they dont work too well past a foot or two away, unless youre reading the temp of a large fire or similar.

8. Working at the Depot, I have had some wheel time with these things!! Lots of it over the winter!!! They are lots of fun and I think they are cool but agree with the accuracy thing. I think the ones that Home Depot sells are more made for telling from hot and cold pipes or hot or cold air duct work and things of that nature from a distance in a more commercial application.

9. But are we really looking for an exact temp or a range?

100-120 too cool

140-160 good to hot

160+ Egg cooking

10. Originally Posted by seaobin
But are we really looking for an exact temp or a range?

100-120 too cool

140-160 good to hot

160+ Egg cooking
preaching to the choir lol, I think there cool and thats a good price too, I think the one ryobi version is like \$59 ish