Looking for red filter to use on this light.
Thrunite Archer 1A V3
https://thrunite.com/archer-1a-v3/
I measured 20mm for the size needed.
Thanks for any helpful recommendations…
Are you just wanting colored glass or are you aiming for more specific filtering? I looked around a lot with sources I’m aware of and didn’t come up with anything certain. The only 20mm ready made I saw were either clear or they were amber focusing lenses for lasers (that would be horrible in a flashlight). I would suggest contacting this seller on Aliexpress and just tell him that you want a 20mm red round glass…try to specify thickness as well, and if you can narrow it down to a nm number or range that might be best. Looks like recently they have increased pricing and/or minimum quantities of items but still not a bad deal and they are a good professional shop, loads of items and gladly take custom requests.
https://tangsinuo.aliexpress.com/store/4314008
Alternatively, Nitecore makes some slip-on “filters” that use glass lenses. They have several models and the sizing is based on the outside diameter of the light bezel/head. Maybe could use one of those (I think the smallest is “22mm”) as-is or perhaps remove the lens to see if it fits or could be trimmed a bit to work as a direct installation replacement. No idea what the thickness is on those, though.
There are also loads of inexpensive 41mm-ish colored glass lenses to fit popular lights. They’re all over aliexpress and you can get a colored set of four for $10 or so shipped to the US. Banggood also has them for a higher price, probably on Amazon, too. Those might be a tad thick and they would need to be carefully cut/trimmed/ground to size if you have the means, but you could probably get three from each lens if you wanted to put in the labor. Some sellers also have the individual colors for sale in various quantities…same pricing or more, depending on who you buy from.
If plastic will work, clear acrylic clipboards are a good cheap source and you could cut one out. They’re a bit thick at around 3mm usually, but it’s easy to sand and polish out to crystal clear if you want (I’ve taken it up to about 2500 grit and that’s darn close to crystal clear). A 15/16” hole saw should be really close to leaving a 20mm plug behind. If you have a drill press you could mount one of those saws and just remove the pilot drill from the arbor, clamp the work well, and gently feed the saw into it. I’ve done that a lot with various sized saws and materials…usually works great but the trick is determining if the plug will be the size you want (that depends on construction of the saw, thickness of the metal for the teeth, how much set the teeth have, accuracy of the set, wobble in the arbor/saw and the drill press itself).
You can buy hobby pieces of red acrylic or lexan, too, either in sheet form or rods. You lose a little light transmission/lumens with this compared to the PMMA that good optics are made with.
Correllux,
Thanks for the suggestions.
Yes, the Nitecore filter is the type of thing I was looking for. Just need the right size- the one they have is 23mm which would be too big.
If I can’t find anything else, maybe I will try it and try to fill the extra space somehow.
My purpose for the red filter is to preserve night vision, using removable filter so the light can still be used normally other times.
Instead of clipboard material you mention, maybe clear red plastic report binder might work, or just filter gel for lighting.
But the cap part is harder to DIY so I was hoping to buy something already made to fit.
Hi electro. I’d think the color gels for lighting would be a good option as you can choose which “red” you want …since there are a lot of different levels of saturation. Companies like Roscolux make a wide spectrum of colors. You might consider a green filter instead of red. From what I understand green preserves night vision very well, and allows us to see more colors than does red. The fly in the ointment for wrecking night vision seems to be the brightness of the light. At a point the filter color doesn’t matter, though this may not an issue with the little Archer.
I looked around some more this morning and thought I found some candidates from a couple companies but nothing quite right. Really looks like the Nitecore is the best bet, and it’s glass instead of plastic, which is good. For such a small gap, if you don’t mind the bulk of the larger-than-ideal size, it should be easy to address. If you can find any small silicone bands (like the wrist bands and such) I bet that would work well. Or some thin eva craft foam that you can buy in a paper-sized sheet for a buck…2mm is common and would work I think but it also comes thinner. Maybe four slivers of it glued in the filter and tapering the edges a little with a very sharp knife to ease entry (and from there the foam will compress nicely and should hold snugly).
I can’t think of any typical flat gaskets/sleeves that would be right, but maybe there’s something out there. Road bike innertubes might be too large and they break down over time. Could always just wrap some electrical or duct tape, too. I think I like the foam idea the best, if it were me doing it.
One note, I did see some filter covers for a Brite-Strike EPLI pen light, but those are supposedly to fit like an 11/16” head. Seems like they’d stretch enough (that’s about 17.5mm). They’re kind of expensive and no idea if the lens would be too small for your light to where it would block or change the beam…or if they’re actually available for sale. Quick link at B&H: https://www.bhphotovideo.com/c/product/1138024-REG/brite_strike_epli_cl_red_epli_flashlight_filter_red.html