Do these numbers seem right?

Hey guys,
So recently I turned my little store room into an integrating ‘sphere’. I did this by way of using a bike work stand to hold the light at a set distance from a ceiling corner. The light is then shone into the corner and is free to bounce around the room, the lux meter is then held 2ft behind the light (distance measure from lens), pointing away from the light into the lowest corner of the room and diagonally opposite the corner the light is aimed at, this reading is then multiplied by 81.3(this number will make sense in a minute).
I ‘calibrated’ this setup using some fuzzy maths and educated guesses. My haikelite MT07 is allegedly 5000lm, it draws ~8amps off fresh 30Q batteries. According to output tests at 8A the XHP70 should be putting out around the 5000lm mark, maybe a touch over. Mine has been dedomed so I have made an educated guess as to its ‘new’ output and placed it at 4800.
This was then divided by my lux meter reading which gives me the 81.3 multiplier.

Using the same set up I have conducted tests on all my other flashlights. The numbers I have gotten sound plausible to me but I would like the opinions of you guys to let me know. It works as a comparison figure for mods if nothing else but I would like the numbers to
Be something ‘close’ to accurate.

The numbers I got are as follows:

Convoy C8 XHP50.2, 80+CRI, 3000k, direct drive, v.closely shaved - 4041 lm
Convoy M2 XML2 U2-4C, direct drive, dedomed - 1050 lm
TN4A Nichia 219b-e, unknown current, Dedomed - 485 lm
Convoy S2+ triple, 3xXP-G2 R5, direct drive - 1696 lm
Ultra fire C8, dedomed XP-G3 3000k 90+CRI, direct drive - 565 lm

Do these seem like reasonable numbers?

Thanks

Thom.

Hi Thom,
You make it pretty difficult assessing output by only measuring heavily modded direct drive lights with non-standard emitters which are often dedomed. Yes, your figures do make sense but it does help your multiplier if you measure at least one stock flashlight that comes with a ANS-measured output number (although guessing by your flashlight collection you have none of those :innocent: ) . This may improve your multiplier accuracy from say 25% to say 10%.

I do like the integrating store room concept, using the corners should (for this method) be optimal for integration. A few questions out of curiosity: is the room empty and fully painted white? Does it matter much for the reading if you move around? (you should wear white clothes :smiley: ) In other words: pics please :slight_smile:

The MT07 is the only ‘stock’ light I own (with exception of its dedome) which was used as a rough baseline using your xhp70 test and my tail cap figures to estimate its output. I only took a couple of % off your test results to account for the dedome as you stated your 70 had been ‘tortured’ in a previous test and lost some output. As for the room, it has a washer and a drier and a few shelves, all are white. There is a single light fixture hanging in the room but it’s just a rose fitting and B22 bulb, no shade on it. My presence does not seem to affect reading by more than a couple of lux but I set my phone up looking at the display and leave the room. I take the reading from 1 minute after the light has been turned on and calculate from there.

The accuracy is questionable but it does work to give me a % difference between one mod and the next, which is all I really need. I think I may purchase a small accurately measured light to calibrate from. But that can wait until payday.