I've had the opportunity to hold a Fluke TiR and a Flir B50 next to each other looking at the same low delta T image. Both are rated 100 mK but the Fluke image was clear while the Flir image was full snowy.  With a higher delta T both images looked similar.  If I looked at an object with zero delta T, the Flir image is very snowy, but the Fluke has very little snow.

 If this phenomena isn't NETD, what is the definition of this image quality characteristic?  Or do manufacturers exaggerate NETD?

Dale

NETD is a good spec but doesn't involve eyeballs. There is no spec for what you describe, only subjective evaluations. You should consider how often you'll be working with low delta-T values. Also at colder surface temperatures the noise typically increases on most systems.

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Thermally Yours,

John
ASNT NDT Level III #48166
The Snell Group
www.thesnellgroup.com
www.thermalsolutions.org
800-636-9820

Thanks, John.  I was hoping there was something tangible I could incorporate into tech specs.

If we get a camera with higher NETD as well as low visual noise, then it would allow a few extra days a year or hours in a day when we can tease out thermal information about a building.  I found the Flir cameras to be frustrating to use for low delta T situations.

Dale Sherman

Development Specialist

NYSWDA Training Center

East Syracuse, NY