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-   -   Infrared Thermometer Minimum Distance to Target? (http://www.diychatroom.com/f29/infrared-thermometer-minimum-distance-target-157574/)

justplumducky 09-21-2012 10:32 PM

Infrared Thermometer Minimum Distance to Target?
 
Considering buying an Extech 42510A Infrared Digital Thermometer.

Distance to target ratio is 12:1. Anyone know is there's a minimum distance to target or will it work for anything in between 12" and 1" of distance from target? Actually, I'm not anticipating needing a measurement of anything small enough to require only an inch of distance from target, just curious. Probably wouldn't need anything smaller than a 1/2" diameter beam. But then again, I've heard you discover all sorts of uses for them after buying one.

Saw nothing on the product page about this at Extech's site.

gregzoll 09-21-2012 11:02 PM

Arm's length is best way to judge. In other words, 2-3 feet, depending on the person.

justplumducky 09-21-2012 11:28 PM

Quote:

Originally Posted by gregzoll (Post 1014923)
Arm's length is best way to judge. In other words, 2-3 feet, depending on the person.

Greg~, I don't get your meaning. I'm wanting to know if the gun can be held as close as one inch from a target, which would make the laser beam diameter 1/12 of an inch in diameter (or just a bit under 3/32"). This gun's distance-to-target ratio is 12:1.

Not really anticipating needing a beam diameter that small (maybe 1/2" diameter), but they say you find all sorts of uses after you buy one.

Thx for your reply.

PaliBob 09-22-2012 01:23 AM

1 Attachment(s)
Quote:

Originally Posted by justplumducky (Post 1014903)
.....is there's a minimum distance to target.......

There is no Minimum distance but for maximum accuracy there is a maximum distance that is dependent on the circular area of the target being measured. Just how much the fan shaped detection beam actually fans out can be approximated with a little DIY experiment:
  • In a warm room.take a glassof water with
  • A couple of inches of crushed ice (not cubes) added
  • Center the laser pointer over the top center of the glass
  • When the laser pointer is just above the ice bath, it should read 32 Deg
  • Slowly increase the distance above the glass until the reading jumps >32
  • This is the height where the detector cone is wider than the glass

justplumducky 09-22-2012 09:40 PM

Very cool - thank you PaliBob!

Fix'n it 09-23-2012 11:14 AM

i just checked my RAYTEK. from 12' to touching the wall = 0 change.

PaliBob 09-23-2012 11:52 AM

The Pali-test is not going to work on the wall. The purpose of using an ice bath in a confined target area (diameter of the glass) against a warm background is that initially the detection area is limited to the ice bath but then as you draw farther away the detection cone area starts to pick up more and more of the warm background so that the IR Thermometer reads increasingly above 32 deg although the laser pointer is still centered on the ice bath.


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