Is this the PWM anomoly?

I was told that if you shake a light really fast in front of my face it will look like a strobe affect if it has PWM. Is this an example of such?

This is an iTP A3 on low...1.6 lumens I think. It does it on medium as well, but not high.

If this is what PWM is, I never noticed it in real world use. Why is this such a concern in reviews?

Yes that is pwm "flicker"

Some people are more sensitive to it than others, at certain hz it can be seen( usually low and meduim levels of a light), and it can be annoying to nauseating.

If it doesn't bother you, your lucky enough to not have to care when selecting a light.

it was the same with the now obsolete CRT screens. Some people didn't even notice when they were running 60hz, others - like me, even could say whether it's 60, 85 or 100hz and be annoyed if it's one of the lower values.

Same with flashlights. Some people are sensitive to the PWM effects and are not comfortable with using such lights, others do not even notice that it's there

OH, I gotcha. I was trying like a son of a gun to think of any application where this would be pertinent as far as lighting something up. It never dawned on me that someone could actually see it. It also makes sense that it would be nauseating.

Thanks.

Pöbel said:

it was the same with the now obsolete CRT screens.

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So if I ever took a picture and my computer screen was in it, that is why I saw horizontal bars?

Sorry to sound like such a retard...I have a few lightbulbs literally going off in my head right now...

exactly.

Images on CRTs are refreshed X times a second (60hz = 60 refreshes per second).

When you take a picture between refreshes the bar is the picture just being refreshed - above the bar the refreshed picture - below the bar the previous one

Well that was definitely educating. Thanks a lot.:thumbsup::thumbsup::thumbsup:

Lights don't do it on high (or shouldn't anyways)
You PWM your high to get your low levels

TwinBlade said:

I was trying like a son of a gun to think of any application where this would be pertinent as far as lighting something up.

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I'm not particularly sensitive to PWM but I notice it the most when any kind of quick movement is involved. Like using your light while running or dropping something and trying to catch it in mid-air while using your flashlight (or even dropping your flashlight when it is on). At night, when I get home from work and take a shower late at night I use a flashlight to light up the bathroom as the main light is too bright and this can disturb my sleeping family. If I use a light that uses PWM then I can see the droplets of water streaming down from the shower head. It's kind of cool in a geeky kind of way.

GarageBoy said:

Lights don't do it on high (or shouldn't anyways)
You PWM your high to get your low levels

Click to expand...

Ok, on my iTP A1, on medium, I REALLY gotta move that sucker fast to get it to appear, but I can get this feathered affect...like a tuning fork on warp drive...to show. It looks almost like a zap of electricity if that looks like anything. Pretty cool. On a side note, my wife was wondering what I was doing. She didn't say anything, just shook her head and walked away. You know...that "been married for 14 years " look that needs no words.

PCC, I broke one of my toes yesterday playing with the dogs and ran it into the corner of the oven square and hard. I am on a couple pain pills and beer right now. May have to try that later when the pain pills kick in. LOL!

TwinBlade said:

OH, I gotcha. I was trying like a son of a gun to think of any application where this would be pertinent as far as lighting something up. It never dawned on me that someone could actually see it. It also makes sense that it would be nauseating.

Thanks.

Click to expand...

There are some places where pwm can affect what you see:
The classic example is rotating stuff that might look like it is rotating slowly or standing still, while rotating very fast.
But anything with fast repeating movement will be affected. Also stuff like rain or snow might look funny with pwm.

damn, my wrist hurts from shaking my leatherman s3 on low mode, no srobe effect noticed, must be not pwm

Yes... I find it most apparent when illuminating running water. Ever try to use it in the rain?... :sick2:... its like being surrounded by bugs, all these little "dots" everywhere.

My wife likes the PWM effect, especially in the rain and snow.

I told her that iTP was upating some of their A3 EOS lights with higher PWM rates, so that would not happen anymore.

I was told that I need to buy some of the original coloured ones for her before they all get updated.

TwinBlade, the A1 and A2 EOS lights use a much higher PWM frequency (1000 Hz I believe) so you won't see the effect on those like you do on your A3.