I have tried searching and reading but for whatever reason I truly cannot find the answer. What causes the cheap lights to emit a square beam when the focal point is extended all the way out?
I thought and somewhat still believe that it is the LED of a certain type/model/designation but I see people changing all sorts of LED's without issue. Are there specific LED's that do this and if so what can they be replaced with to rid that square.
I know some people like the square but it makes me crazy.
It’s the aspheric lens (there are some high end aspheric lights too, it’s not limited to cheap lights). The aspheric lens (technically “Plano-convex”) projects a perfect image of the die when fully focused, only very few led’s don’t use a square die, that’s why it’s the same square image even threw the emitter swap (the SBT-70 is the one flashlight emitter with a round die I know of [lots of larger higher voltage emitters use round dies but not ones used in flashlights]).
I did a zoomie mod with a Osram Oslon SSL80 some time ago, this led has a square die also, but with the led mounted such that you can go through the focus a bit it has a perfectly round hotspot:
Other things to remember, when zoomed in you will always have much lower lumens (since the led is farther from the lens that lens can’t gather as much light- this can be up to 50% loss). And you can stop just a few mm short of fully focused to keep the beam projected round. (You could also use diffuser film on the lens to round the corners of the perfectly zoomed image).
Personally I prefer TIR over aspherics zoomies. Although you can still get a square beam and LED image with them, there really is no need. And you don’t lose the lumens when zoomed either.
there's the LedLenser TIR-ish optic (also in POP-lite lights) that allows zooming, at the cost of a fairly ugly beam. Normal TIR's do not allow zooming.
It's better to call it perfectly collimated instead of perfectly focused. Collimation is what makes an aspheric lens special. It's able to make all the rays of light form the emitter parallel, are very near it, thus producing an image of the light source.
Nah Led Lensers aren’t the recoil style throwers. They use a special TIR optic with a wide opening. Apart from that they work pretty much the same as any other zoomy. Only when on flood mode the LED is actually inside the optic.
As for the beam, it’s true that white wall hunting they can sometimes have less pleasant beams. But the reality I’ve found is that when actually using the lights indoors or outside you simply don’t notice it.
I’ve got 4 POP lites (look like Lenser, I personally think they are made at the same factory or something, although they aren’t 100% copies or the same spec).
My fav is the single mode T33. It runs on 3xAAA and physically is the about the same size as a Solarfoce L2M.
The T33 will out flood and and out throw the L2M with an Ultrafire XM-L drop in that pulls over 2amps. Not bad for an XP-E on 3xAAA’s.
The T33 gives a nice round spot on zoom:
And on flood while it does have a ring you can see on a white wall it somehow lights up an area/circle about 3 times bigger than my other aspheric zoomies do.
That said, I do have an 18650 POP lite the T62, instead of an XP-E likes the others which are rated at 220 lumens, this is an XR-E rated at only 180 lumens. I don’t know if the optic is a different degree angle or something, but on flood the area is much smaller like an aspheric. But it has none of the rings of the T33. On zoom it’s still a circle however and no worse looking than an aspheric in terms of beam quality, but it is round.
And despite this only being 180 lumens, it throws almost as well as my 3amp Qlite driven XP-G2 Aleto aspheric zoomy, that is physically a much bigger torch and has a wider diameter lens than the POP lite.
