I have a SR90 that I’m looking at bringing new life into. Was considering an aspherical lens setup for it.
It started out life doing about 1900 lumens and about 144Kcd when stock.
Next I dedomed it. It went up to about 195Kcd, but down to about 1200 or lumens. Not too good. So its current status, which is pretty respectable, I had Vinh install a SBT-70 on a custom copper pill in it. It now does about 325Kcd and 1685 lumens.
That’s pretty good, but not great. Especially when I have TN31’s and K40’s doing as well or better in lights 1/2 its size using XML2’s.
So I was wondering about the use of aspheric lenses. I know Justin and many others here have played with them a bit.
My concerns are - first I don’t want to screw the light up any more than it is. Meaning I want it to be reverse-able. Meaning if it sucks, just being able to put the old lens back in and done.
Next is about focus. Can I simply buy a optical or asheric lens and install it right where the stock lens is? Or will it require some type of raising & lowering setup to dial in the focus? Like I said above, I don’t want to seriously screw up my light, so would much prefer to be able to just plop it in and be done. It’s got a pretty deep bezel, guessing 15-20mm or so. So I could possible use shims or orings to move the lens in or out perhaps 5-10mm, but that’s about it.
Lastly, does anybody know a good source for a nice lens, but reasonably priced? I see Kaidomain has a few, possibly some that will work. My stock lens is about 92mm. Looks like the inside of the bezel measures 93.5mm.
In an ideal world I would like to be able to plop the lens in the light and get perhaps 5-600Kcd, AND still be able to put the stock lens back in. I’m assuming the stock reflector can be left in, correct? That’s a critical point there. I don’t want to screw with Vinh’s custom setup. He had to drill out the bottom of the reflector to get it to sit on the custom slug and focus properly.
The reason I still want to be able to use the stock lens setup is that even though the lights numbers are so-so for modern modded lights - it’s still dang impressive in person. That huge reflector with SBT-70 setup puts out an awesome amount of flood and spill. It’s very unique and different than, say a TN31, even a 1700 lumen & 495Kcd version I own. The SR90 beam is more impressive visually. It actually has 3 distinct beam angles that you can see. I have even intertained the idea of using a dedomed XML2 in it, but I’m thinking no for a couple reasons. First is the SBT-70 cost about $50 shipped and it wasn’t cheap getting Vinh to install it making the custom copper slug and all. And the SBT-70’s are pretty unique and not exactly weak. Lastly, a XML2 would likely be difficult using the stock driver and battery setup. So I want to keep the SBT-70.
Anyway, I just want more out of it if I can do it without screwing my light up.
So any input, ideas, or links are welcome.
You’ve already gone to a great deal of trouble modifying this one, as well as expense, so it’d be a shame to mess with it at this point. The reflector has to come out to use an aspherical. Yes, focal length on the aspherical is crucial. So a ring of some type, much like what Vestureofblood recently did for the HD2010 is necessary to hold the aspheric in proper position. Finding one with the right focal length for that particular light might not be easy, or cheap. There are several places out there making decent aspherics for the $40-70 price point, with excellent ones being several hundred or more, particularly in that size.
Edit: You might browse a wrecking yard looking for an aspheric headlight that might match, it’d be hit and miss on the focal length though. Or you could just bust out one on the front of your truck and see if it’d fit. 
Darn. Removing the reflector likely will make idea this a bust. I’m assuming it needs to be removed to fine the proper “focus” depth huh? So simply putting it in place of my lens now would be poorly focused I guess. The reflector, other than greatly effecting the depth adjustment, I assume has not ill effect though on an aspheric setup?
I’ll research it some more, but sounds like it might be staying like it is.
http://www.edmundoptics.com/optics/optical-lenses/aspheric-lenses/
http://www.thorlabs.com/navigation.cfm?guide_id=11
At least these places show you the focal length of the lenses, so you can get an idea of the distance from the led. Every aspheric has a different distance from a led, to achieve the "square die" focus. You would have to modify your light and possibly highly modify it, to fit the lens in. As said, you have to remove the reflector too.
You cannot "reflect" light onto an aspheric. The light it uses, is the light that comes straight up off the die. It focuses that light into the square die spot, or defocuses it into a large circle, depending on the distance to the lens. It does not use the light that comes off the die at an angle. (per se). Of course, I could be wrong...
Thanks for the input guys. So, in theory Its possible I could find a 93mm aspheric lens with a working distance of 70mm (roughly the depth of the my reflector) and make this thing work with actually leaving the reflector intact. Correct? If I understand correctly, the reflector doesn’t hurt or help the aspheric lens. It just generally in the way of getting the lens the proper distance from the LED. Am I think correct on this?
And I if I could not get a lens that focuses to the 70mm I need, but perhaps 100mm or so - I could make or buy a new deeper bezel/adapter that could screw on the head directly? If that was done, I would likely be able to play with the depth adjustment more.
So in theory does this all make sense?
From what I have seen, you can't use a reflector in an aspheric. It produces a bunch of "rings" in the beam, outside the center spot and makes a very funky looking beam. I'm sure some of the other guys can verify or correct that statement, but the attempts I have seen, look horrible.
Skip the aspheric on that light - it will hide the lumens you just spent so much to get. I’m thinking you’ll want to do that on something smaller and from the ground up, probably with an XPE2, or possibly XPG2. Something where the reflector, lens, and bezel will all swap out. But still with crazy high amps and a bit of capacity.
Now - if you were talking waiven-type collar … it would probably still need to be in another build.
Message #65 is an example of what Old Lumens is talking about