P60 bulbs brightness test

[Struecker]

When I used P60 bulbs before, I always felt that the brightness of different P60s was somewhat different.
After I purchased the light meter, finally had the opportunity to test it.


I tested 10 surefire P60 bulbs with the same 6P body, the same batteries, and the same distance (very close).
Some of them come from retail packaging, and some come with flashlights, all of which were rarely used before.


If I set the value of the brightest one to 100%, the result is as follows:
1/10 100%
1/10 80%
3/10 70%
2/10 60%
2/10 30%
1/10 20%


The highest one is 5 times the lowest one.

Is it because the production time is too old or overuse is causing such a big difference in brightness?

 

[fivemega]

If I were you instead of batteries, I would use regulated (fix voltage) power adapter.

 

[konifans]

Did you test the electric current?
I also believe that the electroplating of the reflector affects the brightness. Some are more shiny, some are more matt...

 

[broadgage]

Testing with a light meter can be misleading since it only measures the intensity at what ever part of the beam that falls on the light sensor. Minor differences in beam angle or a slightly off center beam will significantly alter the reading.

To measure total light output an integrating sphere is required. An approximation may be obtained by measuremt of the light reflected from a white ceiling.

 

[Swedpat]

Testing with a light meter can be misleading since it only measures the intensity at what ever part of the beam that falls on the light sensor. Minor differences in beam angle or a slightly off center beam will significantly alter the reading.
That's only if the measurement is done at too close distance from the censor. Using ceiling bounce test with the censor laying on a table measuring the beam reflected from a light held ~1m or closer, from the ceiling the beam profile(of a "normal" beam) has an insignificant importance.
But he did not explain how he measured the lux value.

To measure total light output an integrating sphere is required. An approximation may be obtained by measuremt of the light reflected from a white ceiling.
Using a light with a by an integrated sphere measured lumen value as a reference, lumen output can be determined with a very high accuracy, providing the test is performed correctly.

 

[ampdude]

There is a huge amount of difference in throw of SF lamp assemblies and heads, and it's especially apparent in the lower intensity versions such as the P60 and P90. That might be some of what you're seeing. Most of it is due to the amount of sputtering (light or heavy orange peel) on the reflector, and the focus of the lamp. I have some P60's that throw better than some of my turbo heads! Same with some of the extremely light orange peel E-series heads I have and random MN lamps. Almost makes me question the usefulness of turboheads at times if you get the right bulb/head combo in the more compact heads. I'm biased towards throw so I tend to pick and choose and carry the lights with lamp assemblies or heads that throw more like turbos. I do have some E-series heads that throw like turbos, and I definitely prize those.

 

[RobertMM]

Ampdude, you are absolutely right.

I have labelled the sides of my P60 lamps, I put a small T, F or B on them with a marker. Throw, flood or "balanced".
The best throwing ones are a joy to use when there is a bit of fog in the air.