Tempgun question

Not sure where to post this so if this is the wrong spot please move it to where it belongs.

I just got a tempgun from the expo and I've got a question that I can't seem to find an answer to. I have a PE02 from ProExotics and the temp varies a bit based on how far away I am when I measure.

For instance if I measure the same spot from 2 ft away I will get a temp reading that says 85, but as I move closer in on the same spot the temp readings rise, the closer I am the higher it is.

What reading should I trust? The FAQ at tempgun.com says that the PE02 can measure well at 2 ft away and the measuring diameter is around 4 inches. Is there an ideal spot for me to be measuring from? I haven't changed any of the settings, and this is my first time using one so it's a little new to me.

All temp guns (to my knowledge) do this and its nothing to worry about. Typically the gun comes with a piece of paper that will tell you how many degrees to add to the reading depending on your distance from the surface. In fact, this exact chart came printed on the side of my temp gun from Sears.

My suggestion is that you measure a surface from point-blank. Step it back two feet (or what ever your typical distance would be) and take the temp again. Finally, all you do is find the difference and from now on add that to your two foot readings.

To answer your question in short, point-blank (6 inches or less) will offer the most accurate reading.

The accuracy is relative to the distance. If you point it at something 5 feet away, it will be less accurate then if the reading was taken from 2 inches, or point blank.

I'll add 2¢ I guess. The readings done at distance will measure a circle of a particular diameter. That diameter will change depending of the design of the gun you are using. It is often a ratio, D:S Ratio. That means a 1'1 measures 1 inch circle at one inch distance. 4:1 at 4 inches it would measure 1 inch.

Accuracy is not dependant on distance at all it is dependant on the design of the gun they for the part are accurate to +/- 1ºC or 1.8ºF up or down. The emissivity is complicated and hard to explain simply so the simplified version is how much the gun reading is reflected. The typical general purpose gun is set up to be looking at brown paper. If you point at say the plastic of the tub the reading may be wildly inaccurate as it could read something else (your hand for example)

As for your question I would not hold 'point blank' but rather at about 3"-6 or so if you had say a PE1-2-3 you would be measuring an average surface temp of 3-6 inches Remember exactly perpendicular and a low reflectance and dark brown object for the most accurate readings. Personally I'll check a 4 in distance go in a bit and scan it over the same 4 inch circle (slowly scan) and average off the readings. And compare the two.

Thanks for all the info guys. The gun came with a somewhat humorous but not very informative sheet of paper so I wasn't sure if there was a "perfect" range to be measuring from. I think I'll try it out the way kitedemon does it. Thanks again!

well i have a PE-1 temp gun and i check the temps at an inch above the middle of the spots i'm checking. like in the middle of the area directly above where the heat pad is. i also check the temp of the bare surface there cuz my girl pushes the bark away to sit on the bare surface so i wanna know exactly what she's sitting on.
if the temp readings i've been getting all along are higher then what i've thought then some of those warm side temps have been 100-102 but my girl does not have a burn so i think she's ok. when the temps i get reach 98+ i'll turn the thermostat down a tiny bit until the temp goes down to around 90-93.
i quit stressing that i wasnt getting exactly 90/80 and just settled for 85-90 warm/75-80 cool. but because i'm neuroticly monitoring temps and adjusting the thermostat to stay within those ranges it never dips below the lowest in those ranges.

yeh i got a PE2 aswell, and was measuring from like a 2 feet away like a idiot, got a more accurate reading when i got closer, liek 4-6 inches, i noticed my BP spending more time than usual in his cold his and when i checked the by where the UTH was it was 104! so i lowered the dimmer and check again in a few hours and it was back down to 92, so yeh 4-6 inches is way more accurate cuz he now stays more in his hot side hide.....

oh, yeh those intructions are very "humurous" it looks like a college kid wrote it up in his dorm or something

The PE-2 unit has a 6"1 D:S ratio. At 6 inches away you are measuring a one inch spot. At a foot away you are measuring a 2 inch spot. At two feet away a four inch spot. That information is included in the instructions.

Within a four inch area (or certainly a 12 inch area) you may see a number of different temperatures, especially if your heat tape or bulb is heating smaller area. You are reading an aggregated average of the entire spot.

I typically use the PE-2 unit at a foot away or less, for reptile setup temps.