Lux-V, reflector Question

I have a M*g head with a Lux-V in it and it has a pretty good size donut and the hot spot isn't round -- sorta square. Is this unavoidable with the V or can it be remedied by changing the Lux - reflector distance?

The reflector is polished.

The donut can be reduced by focusing the head. As far as a square spot is concerned, I haven't encountered that. The spot I get is a 'furry' spot with a slight dark spot. I am using the stock reflector.

yes, it is unavoidable. but hey, unless you really want focus, you can try to sand the reflector around 2 to 3 mm more, to move the lux V up,it will make it lose focus but i think the donut will be loss or just around very slightly.

or you can find some HOP reflector which will smooth the beam out ALOT and hopefully kill the donut.

plz, don't blame me if it doesn't work. both are still in theory stage

My LuxV Mag uses a Hotlips heatsink so the reflector can be positioned slightly below the height of the LED die. No doughnut is noted when I move the Mag head to focus the beam. If any darkness is in the center, I adjust the focus a touch to "fuzz" the focus slightly to get an even hotspot.

I did notice a doughnut effect when I made a 2D Mag with a madmax regulator pushing an R2H LuxeonI. The reflector could not drop far enough because of the flat heat sink. I think the sandwich shoppe still sells the hotlips or osink to take care of the focusing problem.

I've found that the 'donut' on some LuxV's are worse than others....Don't really know how this could be...must be down to manufacturing inconsistencies.

I have 2 Lux V magmods....When using the same mag head and reflector - one has an obvious donut and the other has almost none!

If you can't focus it out via the adjustability on the Mag head then your only real option is to go for MOP / HOP reflector.

Changing the emitter could work....

Could be that newer LuxV's are more consistent....My 'donut' version is an old 'U' bin.


Good luck

Tim.

Sounds like you are close. Ya need to adjust the height of the led or change the range of adjustment of the head. I don't know how to do that with a Mag. Moving the led seems like it would be easier.

I have spent some time working with the focus of a Lux V and a McR38. I had a bench setup that allowed precision measurement and movement of the reflector.

I am not a scientist. Just reporting what I believe to be correct about a specific Lux/reflector combo. Some of it may apply to your mod.

Since the McR38 is designed for relatively tight focus, it is easy to see the results of slight movement relative to the "hole". In the focus range that produces a noticable hole, movement of less than .003 made little difference to my eyes. Things got noticable with .005 changes. That's about the thickness of a piece of paper.

Here are some of the things I noticed:

1. The "hole" is caused by bringing the 4 individual dies of the Lux V into focus. The more they are focused, the more distinct the hole will become. It will become an "X" at the tightest focus. (all of this at about 3 feet)

The hole will vary with distance from the light. At normal usage you may not see a hole at 15' that looks bad at 3 feet. The hole is much more noticable at lower current settings.

2. It's all about reflector type (flood/spot) and focal plane - the height of a particular reflector relative to the LED die.

3. Not all "identical" reflectors have the same focal plane. Due to manufacturing and mounting methods, it is easy to have the height vary enough to make a noticable difference.

4. The led (other than the die height issue with Jokers) is the most consistant part. Seldom will changing led's make a difference unless you change the height of the die when you swap the led.

5. Flood type reflectors have a wide range of "good" focus compared the spot types (duh). There is a lot more room for error with a flood type reflector. The SFIII-V light is a good example. They removed about .250 from the bottom of the McR38 reflector. This made it impossible to focus tightly, as designed.

It produces a large, very floody hot spot with slightly more spill than a U2 and no sign of a hole in the beam. My full length McR38 produces a tighter beam with less spill than the U2. Quite a difference due to focal plane with the "same" reflector.

6. Lux V's have 2 different die heights. They differ by around .015. It matters. Using a reflector that works good with the old style die will almost certainly cause a problem with a Joker. There is a lengthly discussion of the Joker in McGizmo's area.

i designed a special reflector for the LuxV.. it uses 4 'quarter' reflectors to focus at each of the 4 hot spots of the 4x1W lux dies inside.. i've never been able to get a chance to build one but was planning on taking either a 20IMS for starters or a McR38 and cut it into quarters to make the 1 or 1.5mm offset to make it .. the 'tester' that is hand-made would of course have some efficiency losses due to the cuts.. but after examining some very detailed pictures of the reflectors it is quite clear that the closest die really makes the most of being closest to the focus.. the idea is that each quarter reflector would be aligned to be in focus with the nearest led die rather than focused on the dead (null) spot between all of them.

It should work like a charm to improve the focus of a LuxV.. i would LOVE it if somebody else had the time to chop up a reflector or 4 (or 2).. to make it happen (with more than 1 you can cut them a bit bigger than 25% and not lose the saw kerf).

-awr