Lee minus green and Zircon minus green filters durability test

After putting an eight minus green filter on a H600Fc IV I saw it losing its effect quite rapidly, like after one or two runtimes. This prompted me to switch to Zircon filters as they are supposed to be more durable.

Since then I got a spectrophotometer so I decided to test their durability.

For this I use an YPL Unicorn 1.0 (LH351D) which has a maximum output around 800lm, and a sustained output around 400lm.
It has a PID thermal regulation and the head surface temperature stays constant around 40°C, the filter is placed in front of the TIR optic, there is no glass lens on this flashlight (possibly the filter is at a lower temperature this way).

The light is plugged to a bench power supply so it can be powered indefinitely.

I measure the spot chromacity (CCT and Duv) and illuminance (lux) at 30cm at low output (level 2/5) when the flashlight is at ambient temperature so that the chromacity measurements aren’t affected by the temperature.

I power the flashlight on level 5 for an amount of time, then turn it off, wait for it to cool down (with a fan to speed it up) then measure…etc.

Results :

The classic filter loses strength quite rapidly but then degradation slows down. As a result some more light passes the filter but it’s not proportional.

The Zircon filter barely degraded in 10 hours.

Edit : ran the Zircon for 30hours and it shows a bit of degradation.

No idea about the paint but that would be a good information to know (as well as output cost) considering it is a permanent solution.

I’ll let it run today again and report back.

Nice information. Thanks for putting the effort into this and letting us know the results!

> LH351D

dedoming reduces duv about 0.0030
it also lowers output by about 20%

not a fan of Lee filters… I wiped one of the regular minus green from the swatchbook with alcohol, and the pink color came right off.

I also noticed that isopropyl alcohol is not suited for lee filters, don’t know about ethanol.

LH351D tint is improved by slicing with a similar cost to Zircon 804 and similar effect on duv (but lowers the CCT a lot), with other improvements (tint shift, throw). I don’t know which other LEDs gives good results but with SST-20 I didn’t measure any improvement, with XHP50.2 it got worse (while reducing tint shift a bit), I haven’t tested on other LEDs (219C ?).

Lee filters will work with any led and are much simpler to use, also sometimes swaping the LED is difficult or there is simply no good replacement (e.g. H600 IV), so IMO they are quite useful.

20 more hours on the Zircon 803 and it shows a bit of degradation.

anything we use to change the tint of a light, also lowers its output.

for example, a Lee 803 filter drops output by 20%

I would rather choose an LED that has tint I like, than add a Lee filter to an LED whose tint I dont like.

I did have fun testing Lee Filters, but they did not make me want to use a Low CRI LED with filtered green tint, when I could have a High CRI LED that did not need a fragile plastic filter added.

Just checked the 804 filter I installed in my ROT66v2. After hundreds of hours of usage, the 804 filter shows no signs of fading under visible light and uv light. I also compared its filter to the fresh 804 I still have rolled up, and see no visual difference.

Yeah, but there are no good emitter options for Zebralights. They’re all green-tinted Crees. If only they had the emitter options that Convoy and Hank do…

The filters are fun to play with but don’t really represent a permanent solution to fixing substandard LEDs. The orange filters can make anything with Anduril and pretty good candle.

Up until very recently, all of the data for Lee filters was available on their website, with transmission rates and changes in CCT. Unfortunately, all of this data has been removed and replaced with a very cool but less useful UI. The Zircon data has been removed, but most of the data for all of the other filters is available. Maybe the change was sharing proprietary information they didn’t want to share anymore because I think they got bought out recently.

LED manufacturers seem to be very open with sharing data which is useful and takes a lot of guessing and subjective opinion out. I wish other companies would do the same (audio companies for example) and I respect the companies that make this kind of information available to consumers.

Well, that’s a nice workaround and all, if you want the particular ZL model he’s selling, but it’s still not the same as ZL itself offering it on every light the way the other companies do.

Lee says the zircon filters are 200x times tougher than regular filters . I'm not sure that means they last 200 times longer ...but they are a much thicker and tougher material that's for sure .

Standard filters tend to fade and become much less effective after relatively short exposure to LEDs. The Zircon filters can hold up after hundreds or even thousands of hours with minimal degradation.

I have a few lights that I have installed Zircon filters which I consider to be a perfectly adequate daily use solution. For example, a C8+ with LH351D 4000K and a Zircon 803 comes in at 3950K, Ra 98, R9 96, duv –0.0017 and ~1000 lumens on turbo with a H17Fx driver. It makes a great nighttime trail light.

I agree, and it looks like Zebralight will be sticking to Cree for most models in the next gen lights too. On the plus side XHP50.3 HI and XHP70.3 HI have much better looking beams than XHP50.2 and XHP70.2, but it’s hard to get a really nice tint.

FWIW my post on BLF is very outdated because most of my orders are through Reddit. I can do any Zebralight model and have some nice options for Cree replacements, but the SC64c LE is particularly popular because it’s the only 18650 model that can take 519A, 219B, etc.

It’s a shame because offering a couple of choices for better quality LEDs would make Zebralight one of the top tier contenders in the enthusiast community. So much potential there. I assume they just don’t have the tooling for large numbers of SKUs or custom orders for what is admittedly a small enthusiast market.

Lots of guys buy minus green filters for these harder to mod lights like the zebralights . It takes a pretty talented hand to mod them. while some guys are struggling to cut out a perfectly round circle Bob shows the factory how lights are made in a perfect world ...

*Note to self ... Kill Bob McBob

I put two layers of 804 in the D4SV2 W2. It’s a rosy 5700k with low CRI. There’s no green on lower mode. I’m hoping after 30 hours of use both 804 will lose intensity to get a more neutral tint.

Heck with that! I use a series of craft punches of various sizes that punch out perfect circles of dc-fix and minus green.