Changing LED Tint With Filters

[Derek Dean]

That would be fun way to teach kids about light, and would be an excellent compliment to using a prism to split light into it's basic components. Nice idea.

[Got Lumens?]

Since everyone on here has multiple flashlights and presumably a filter pack as well here is an interesting light experiment.

Tape a red, blue, and green filter over 3 lights (one each of course). Prop up a white piece of cardboard or paper on your desktop as a background and stand an Eneloop (or anything really) about an inch in front of that white background. Turn on all of the flashlights and aim them all at the Eneloop. So you will have a spot of red, green, and blue all coming together.

Where they all come together behind the Eneloop will be white. Any area where they don't overlap at all will either be blue, green, or red. There will also be 3 shadows and they will be cyan, yellow, and magenta. If you position the lights just right you will also have some areas with just green, some with just blue and some with just red (just is behind the Eneloop where only one color gets through).

You will have 6 colors in all from just 3 light. Try moving your hand just in front of the white paper as well for a more dynamic effect...you will get the same shadow effect of yellow, cyan, and magenta. You might even be surprised to see that green and red makes yellow!

For anyone reading this who doesn't have your filter pack yet just use 3 clear drinking glasses and some food dye ($3 from any grocery store). Put some blue dye in one glass, red in another glass, and green in the 3rd glass and position each flashlight behind each glass for the same effect.

It's fun...what can I say!

Gcbryan,
Do you have reference names and numbers for the Red, Green, and Blue filters from the sampler pack?
I would like to try this using three 4 sevens Preon lights. I have R5 and S2 to compare.

I have another interesting experiment you and I can try. Find the best position for a camera and use tripod. Then take Photo using all three lights on together. then take three seperate photos of each light on by itself, and see if you use overlay photo technology if it comes close to all three picture.
Thanks
GL

That would be fun way to teach kids about light, and would be an excellent compliment to using a prism to split light into it's basic components. Nice idea.

+1

[gcbryan]

Gcbryan,
Do you have reference names and numbers for the Red, Green, and Blue filters from the sampler pack?
I would like to try this using three 4 sevens Preon lights. I have R5 and S2 to compare.

I have another interesting experiment you and I can try. Find the best position for a camera and use tripod. Then take Photo using all three lights on together. then take three seperate photos of each light on by itself, and see if you use overlay photo technology if it comes close to all three picture.
Thanks
GL



+1

It's not all that crucial which red, green and blue is used...go for the darkest but I used #3202 Full Blue,#42 Deep Salmon, and #91 Primary Green. I just used these for the deepest color that I could find.

The photo experiment is interesting but I don't have the software for that. If you do it let me know how it works out.

[Got Lumens?]

UK: http://www.leefilters.com/lighting/contact/
Canada: http://tyi.ca/contact/

Response I got from Lee Filters for purchasing outside US.
GL

[^Gurthang]

I will mention that there is another major filter / gel supplier that will send a swatch sample book. Its Rosco.

http://www.rosco.com/us/products/lighting.cfm

The swatchbook request link is at the bottom of the page. BTW the book is free but Rosco charges $7.50 for shipping....

[vincevoxbox]

ive got a book ordered..on its way now.. thanks everyone.

[atlashomeric]

Hey guys, new to the forum but have been looking around them for awhile. I'm glad that there exist such insight in lighting on the web. I thought I'd chime in on this thread and just say that most people overlook color temp when looking into either flashlights, bike lights, etc. I think that lighting color can really make the difference in many situations. CRI plays a role in distinguishing the difference between rocks, ruts, or shadows. I am an avid outdoorsman and have found that a flashlight or headlamp with the correct CCT can make the experience that much more enjoyable. I usually try to look into 5500-6000K range. I found some good info featured in this blog.

Link removed. Links in first posts are generally not approved, especially when link is to a dealer blog with a link to their store

Bill

[Derek Dean]

Howdy atlashomeric, and welcome to CPF,
Yes, the general public doesn't pay much attention (yet) to the color temp of their flashlights, but I think you will find that around CPF most folks take the tint of their LED lights VERY seriously.

Some folks will search out the best tint bins to find an LED with the color they like, while some of us simply add a filter. Some mainstream manufacturers are even beginning to offer lights with "high CRI" LEDs, so things are looking up.

In any case, I hope you enjoy your time here on CPF.

[atlashomeric]

Howdy atlashomeric, and welcome to CPF,
Yes, the general public doesn't pay much attention (yet) to the color temp of their flashlights, but I think you will find that around CPF most folks take the tint of their LED lights VERY seriously.

Some folks will search out the best tint bins to find an LED with the color they like, while some of us simply add a filter. Some mainstream manufacturers are even beginning to offer lights with "high CRI" LEDs, so things are looking up.

In any case, I hope you enjoy your time here on CPF.

Thanks Derek,
Yeah I'm just curious where you get your filters, and in that case where you go to first to search LEDs. DigiKey, Mouser?

Thanks,

[Derek Dean]

Here you go:
In the US you have at least 2 choices for filters:
http://www.rosco.com/us/products/lighting.cfm (scroll to the bottom left of page)

or

http://www.shop.leefiltersusa.com/De...h-Book-SWB.htm

In Europe:
http://www.leefilters.com/lighting/contact/

To search for LEDs, you will need to do some research. You will need to go to the Cree website and educate yourself on how they classify their LEDs by tint bin.
http://www.cree.com/

Then when you are ready to order, go here:
http://www.cutter.com.au/

There is probably a place on the CPF forum where they discuss specific LEDs and such, maybe in the electronics area, so get a cup of coffee and look around.

Have fun.

[gcbryan]

There is a LED sub-forum here.

[Harry999]

Edit: By the way, if you live in Europe or the UK, you might have better luck requesting the Swatch Book from the UK Office:
http://www.leefilters.com/lighting/contact/

Thank you Derek Dean. I have requested one. This is a great thing for you to share.

Regards

Harry

[Derek Dean]

You're most welcome, Harry. Have fun, and let us know how they work out for you .

[LedTed]

Hello all,

I took my wife to the ballet this weekend. In the production color was used symbolically. A set of dancers came out with LED FLs which had blue gels on them. The experience made me think of this thread.

[Derek Dean]

So, I got a new light (Yippeee), the ZebraLight SC600. I had been waiting for the neutral LED version, but it's been so long that I finally decided to go ahead and get one with the cool white XM-L T6 and see what I could do with the filters when it arrived..... and..... I decided this might be a good chance to photograph the results.

Well, it arrived, and while the light itself was totally cool and everything I hoped it would be, the tint of the XM-L LED was an awful puke green/yellow... arrrrgghhhh.

Lee Filter Swatch Book to the rescue! It took a while to figure it out. I started with a half-minus green, but that just wasn't enough, so tonight I finally went with a #247 Lee Minus Green filter (CC30M equivalent), which is a VERY strong magenta filter, and that finally got the tint back in the liveable range.

Here are the photos. These were all shot with the white balance on my Canon G10 set to DAYLIGHT. The shutter speed and aperture were the same for each set. The top photo of each pair is the unfiltered light and the bottom photo has the filter added. Judge for yourself.

Do understand that I was hand holding both the camera and the light, and that I had to take out or add the filter between shots, so the angle of the lighting has changed a bit from shot to shot, but I think they still get across the point.


UNFILTERED 1/25 second at F3.5, WB set to daylight.


FILTERED 1/25 second F3.5, WB set to DAYLIGHT.


UNFILTERED 1/60 second F4.5, WB set to DAYLIGHT.


FILTERED 1/60 second F4.5, WB set to DAYLIGHT.


I'm a much happier camper now with my newly filtered light.

[DM51]

Excellent result! The filtered light doesn't seem to have lost much brightness at all, and the colors are FAR better and more natural, with all that zombie-green color cast taken out.

[varuscelli]

Nicely done, Derek.

[Cataract]

Amazing result! This is the best discovery so far. Now, if I can just kick myself to start using my filters...

BTW, the book I got is the Designer's Edition WITH Numeric Numbering... best of both worlds!

[B0wz3r]

Wow! Derek, that's amazing! The improvement is simply phenomenal...

Just as an aside, for fun a while ago I took the red filter from a 4Sevens prism kit and tried it on the front of my Jet-3 Pro ST with a neutral/warm XRE Q3/5B emitter in it... the result was purple! Since purple can only be created perceptually by mixing red and blue, there must be a strong blue spike in the XRE's power spectrum that isn't filtered by the 4Sevens red filter. I don't have any specialized equipment to test this out though.

[GunnarGG]

Very impressive!

Since I saw this thread I have been looking for those filters in Sweden/Europe.
I did find some place that sold them but it was a lot of money for shipping.
Anybody that know a place to get them without high shipping cost?

[Derek Dean]

Yes, I'm happy with the results, however, I will mention one caveat. While the LEDs in all of my XP-G based lights had a single tint that was easily filtered and corrected, this particular XM-L T6 LED has the unusual characteristic of having an angry green/yellow center spot/corona, but with a slightly cool spill, so of course my single magenta filter, which has wonderfully corrected the central portion of the beam, has left the spill with a slightly purplish tint.

That was why I initially went with the 1/2 strength magenta filter. It helped with the center spot but didn't affect the spill to much, a nice balance...... but after using the light for a few nights I found that I really needed the central portion of the beam to be more neutral, so my first thought, and what I actually tried, was to create a two toned filter by combining a slightly warm outer filter (for the spill), then cutting a hole in it's center and putting a small magenta filter in there for the spot, ha.

Well, that just didn't seem to work, so I went ahead and tried the full magenta filter by itself, and was much more pleased with the results. The central portion of the beam is what I use the most, and like most things in the flashlight world it seems that we must make choices and find the best balance for our own situations, and at this point I think this is a result I can live with, because in real world use I've found I don't really notice the slight tint of the spill, while the beautifully neutral spot tint is quite useful and pleasant.

[MikeAusC]

. . . there must be a strong blue spike in the XRE's power spectrum that isn't filtered by the 4Sevens red filter. I don't have any specialized equipment to test this out though.

Do you have a pre-recorded Audio CD ? The non-label side makes a good diffraction grating.

I find if I look at the torch image reflected off one side, the other side has the rainbow spectrum on it - with the blue region being very bright.

A yellow LED has edges either side of the Yellow showing it spreads into the Green and Amber.

[B0wz3r]

Do you have a pre-recorded Audio CD ? The non-label side makes a good diffraction grating.

I find if I look at the torch image reflected off one side, the other side has the rainbow spectrum on it - with the blue region being very bright.

A yellow LED has edges either side of the Yellow showing it spreads into the Green and Amber.

Neat trick... I'll have to try it when I can. I rarely use even optical media anymore though, so I'll have to dig one of some software out of storage.

@Derek; I've encountered what your talking about twice now. My PA40 neutral I got a couple of weeks ago does exactly what you're talking about, gangrenous piss colored corona and a slightly blue/purple spill. The new neutral XPG Preon 2 I got also has exactly the same characteristics. Cree must have changed something with their phosphor coating process for their neutral emitters that is not working out well.

I don't mind it in my PA40 because that's become my dedicated backpacking / hiking / camping light, so it's not nearly so noticeable outdoors. The Preon 2, however, I meant to be an EDC light, and I just can't stomach that awful tint combination for EDC uses.

[gcbryan]

Wow! Derek, that's amazing! The improvement is simply phenomenal...

Just as an aside, for fun a while ago I took the red filter from a 4Sevens prism kit and tried it on the front of my Jet-3 Pro ST with a neutral/warm XRE Q3/5B emitter in it... the result was purple! Since purple can only be created perceptually by mixing red and blue, there must be a strong blue spike in the XRE's power spectrum that isn't filtered by the 4Sevens red filter. I don't have any specialized equipment to test this out though.

That's the deal with most of these filters. In theory a red filter would only allow red to pass and it reality (and the filter charts show this as well) it allows a large percentage of red to pass and a smaller percentage of the other colors to pass. I have some transparent diffraction material and even my UV light allows other colors to pass. My laser pointers are the only ones that are only a single wavelength. My red LED's are mostly red but they do have a bit of other colors passing as well.

[gcbryan]

Yes, I'm happy with the results, however, I will mention one caveat. While the LEDs in all of my XP-G based lights had a single tint that was easily filtered and corrected, this particular XM-L T6 LED has the unusual characteristic of having an angry green/yellow center spot/corona, but with a slightly cool spill, so of course my single magenta filter, which has wonderfully corrected the central portion of the beam, has left the spill with a slightly purplish tint.

That was why I initially went with the 1/2 strength magenta filter. It helped with the center spot but didn't affect the spill to much, a nice balance...... but after using the light for a few nights I found that I really needed the central portion of the beam to be more neutral, so my first thought, and what I actually tried, was to create a two toned filter by combining a slightly warm outer filter (for the spill), then cutting a hole in it's center and putting a small magenta filter in there for the spot, ha.

Well, that just didn't seem to work, so I went ahead and tried the full magenta filter by itself, and was much more pleased with the results. The central portion of the beam is what I use the most, and like most things in the flashlight world it seems that we must make choices and find the best balance for our own situations, and at this point I think this is a result I can live with, because in real world use I've found I don't really notice the slight tint of the spill, while the beautifully neutral spot tint is quite useful and pleasant.

That doesn't work because the spot isn't coming from the center of your reflector. It's coming from the whole reflector. That's what the whole reflector is doing...collimating light. The center is actually where the spill is coming from...light that is going straight out from the emitter and not hitting (or being collimated) the reflector.

[Derek Dean]

gcbryan, I had a feeling it was something like that, but I thought I'd give it shot anyway. The first thing I tried was just putting my finger over the center, and there was still light there on the wall, so knew it was a long shot, but I thought it would be an interesting experiment anyway, and it was.

I wish I knew why these new LEDs have this two tone tint thing going on, it's certainly odd.

[gcbryan]

gcbryan, I had a feeling it was something like that, but I thought I'd give it shot anyway. The first thing I tried was just putting my finger over the center, and there was still light there on the wall, so knew it was a long shot, but I thought it would be an interesting experiment anyway, and it was.

I wish I knew why these new LEDs have this two tone tint thing going on, it's certainly odd.

That is odd. Maybe someone else will have more info for you. Could you use the lighter magneta and then try another filter to complete the tint? For instance there are filters that say they correct from 5400 K to 4500 K or something like that. Use the lightest magenta you can to reduce the green and then use one of those filters. Maybe the combined effect will result in the tint you want without the purple spill (which you are causing after all).

Nice pictures by the way. The after shot is certainly better than the before shot!

I'm glad we have this thread. There are so few interesting topics on here these days

[gcbryan]

Amazing thread Derek! Love the beamshot comparison on post #103, I wish more people would post pics like that so I could have some eye-candy anticipation while I wait for my filters.

I ordered a designer edition (practically free at 1 cent) and a numerical version just for kicks. I have become quite the tint snob as of late, and these filters will be very fun to play around with on my lights! Do you know where they ship from, or how long it might take for me to receive them? (I live in Cali).

My NW Quark also has the bluish spill and the yellow hotspot (greenish yellow on the lower modes), so I hope I can find something that will give me a good tinted hotspot and a desirable spill, cause both are important to me. One thing I am wondering is how the filters will hold up with the mode tint-shift that my 4Sevens lights have. My NW quark is almost perfect in max mode, then as I cycle through the lower the modes I get the unnatural greenish pee colored tints. I fear that if I tweak the tint on the lower modes it may severely impact the tint on the max/high mode.

Either way will be a fun experiment, and I cannot wait to get my filters. So what exactly are these filters? Just hard plastic or are they gel-like? How thick are they and can they be cut easily? Surprisingly nobody has posted any pics of the actual filters in this thread.

The Lee Filters only took about a week to arrive. The Rosco filters took several weeks. The filter material is more like cellophane and is easy to cut.

[gcbryan]

Thanks Bryan! You know I was thinking, it would be really neat if somebody would sell flashlight filters like this but instead the material would be that thin plastic/rubbery material that is often used in cell phone screen protectors and those non-permanent stickers for glass windows (it would stick to the outer lens securely without any need for glue). How awesome would that be! Plus they would be pretty easy to remove and replace.

I agree, or have slotted filter holders incorporated into bezels or simply threaded bezels that serve as filter holders. They could just thread the outside of the face for screw-in filters like they have on cameras.

[psychbeat]

If u cut the filter to the same size as the lens the bezel should hold teh filter over tha lens on most p60 hosts. Just screw it down on top o the filter.