I'm looking to do some runtime measurements that are likely to run multiple hours so I don't want to take a reading and write it down every 5 or 10 minutes. The ideal solution is a measuring head that plugs into a USB and PC or Mac software. Next best is a logger with a memory stick or SD card. I want to spend less than $200. I don't need NIST traceable calibration. If you have experience with a system I'd love to hear about it.
Recommend me a data logging LUX meter
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Tachead
Flashlight Enthusiast
If you up your budget an Extech HD450 is a good option. You will likely have trouble finding a new high quality datalogging light meter that is accurate for under $200.
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I think I've solved my problem. I don't need a data logger. I acquired an app for my phone OSnap that allows me to take time lapse photos with control of the time and exposure. The plan is to fix the time increment based on about 100 photos over the expected runtime, turn on the light pointed at a grid target on a wall, lock the exposure and let the time lapse photos run. I think I'll be able to resolve 50% and certainly 25% brightness from the photos. This should be OK for the longer duration tests I want to run of medium and low outputs. If this doesn't provide the accuracy I want, I can buy in inexpensive light meter, lock it in the reading position and take time lapse photos of the meter readout. Now I just need to get out of this hotel and back home to test it.
Why don't you just take tailcap current measurements with a decent DMM? I used to runtime test sub- and low- lumens and but now rely on current measurements ($25 DMM) - they triangulate well to my actual runtime tests, and it just takes seconds.
Don't know if you care about spec accuracy, but manufacturer lumen exaggerations are the other half of the equation. A BLF plug & play lightbox can be had for <$40 and is quite accurate - my ties up with HDS and ti-force (only reviewer claiming ANSI accuracy).
Don't know if you care about spec accuracy, but manufacturer lumen exaggerations are the other half of the equation. A BLF plug & play lightbox can be had for <$40 and is quite accurate - my ties up with HDS and ti-force (only reviewer claiming ANSI accuracy).
gravelmonkey
Enlightened
Common "quick and dirty" timelapse runtime test use a digital clock in the shot. Switch it on when you start the timelapse and it will give a duration.
Else, I think an Arduino based contraption with a light sensor and some simple code would do what you want; it is something I want to build but haven't had time to investigate yet so maybe I'm wrong...
