Blue lens for blood tracking does not work w LED... Why?

Please watch about 2 minutes of this video clip

Why does Incandescent show Red, and the LED does not?

A low CRI high CCT light source means there’s almost no red being emitted from the light source.

IE, low dynamic range.

Good video & info, thank you.

my thoughts exactly

.

Secret to blood tracking:

1. HIGH R9
OR
2. An assistant spraying the area with Luminol and a good UV light.

Matt - Adventure Sports
Did a test of this a while back

All the Best,
Jeff

thanks I did not see a test w a blue lens and a low cri light

he got good results with a green and red combo, no blue filter either…
.

that seems useful, since there are typical headlamps w green or red leds these days… double up and Viola, Bobs your Uncle.

some other photo clips from Matt’s video:
red+green compared to Cool White:

red+green compared to Warm White:

Leds do not work with color lenses, there are color leds for that. Once i tried green and blue led to shine on a grill while meat was cooking, well lets just say it looked very unappealing, lol.

How much of this is just the blue lens neutralizing the color spectrum of the 2700k incandescent to something more akin to a a neutral white, while it takes an already cool white led and makes it virtually blue altogether with no other color information?

I think a true test would be comparing a 5700k or 6500k high CRI led vs a 5700k or 6500k low cri led with blue lenses over them.

Also it seems as though Matt found the low cri cool white LED and high cri warm white LED fairly even in terms of contrasting the blood from the rest of the leaves. High CRI warm white LEDs may have plenty of red in their spectrum, but the rest of their spectrum isn’t balanced enough to give the highest amount of contrast between the blood and leaves. I think a high cri cool white LED would perform best. Even something like a 4000k would have a considerably better spectral balance than say a 3000k light source.

have you tried High CRI LEDs?

LEDs are essentially monochromatic. They’ll have a peak wavelength and dominant wavelength that’re very very close to each other, and very little else outside those peaks.

Phosphor throws in bunches of other wavelengths, though. Like (duh) white LEDs. But PC (phosphor-converted) color-LEDs have other wavelengths as well.

Eg, my Anakim PC-green light is unlike mu HS-802 green light.

My ’802 shows pretty much just green and black. Anything with green content (actual green, white, etc.) will show green, whereas reds will show pretty much as black.

My Anakim has enough spillover of other wavelengths that while the scene is definitely tinted green, you’ll still see reds, blues, yellows, etc., but of course more faintly.

It gets even more fun with monochromatic amber, PC amber, and 1800K-2200K WW.

you did not answer the question

Didn’t need to. High-CRI implies better color balance, ie, not a peaky curve (blue peak, cyan valley).

A high R9 value would’ve been more appropriate vs a generic high CRI.

Im getting very confused.
I think you just said High CRI does not have a Blue Spike and Cyan Valley.

afaik High CRI does have a Blue Peak and Cyan Valley:

so I dont understand why you quoted me…

I have no experience tracking blood in the dark of night, so I was asking if anyone here has ever tested High CRI through a blue filter… Adventure Matt, did not.

They all do, but some low-CRI LEDs have a blue spike which’d pop through the top of the graph, and they pretty much all have the cyan valley (few phosphors that’d reradiate so close to the exciting wavelength). Even seriously WW high-CRI LEDs have both, but they’re kinda “ironed down”.

Luck of the draw. Buncha comments about it, didn’t want to grab everyone’s. Too much work.

Point being, blue filters pass blue and block non-blue, relatively. LEDs are more monochromatic than hotwire bulbs, and have a more irregular… whatever you call it.

(Bad case of The Itis, wanna go to sleep for a while.)

Probably not much difference unless a high R9 value. Think that’s what I started out with, so… full circle?

Have you?

When shining spider eyes or any eyes they reflect much better when you hold the light over your head. Maybe blood would reflect better holding light on top of head.

Blood isn’t retroreflective, though.

Ok