Is it possible to focus a PR-T???

Hey guys,

I've been devoting an uhealthy amount of time to playing with my PR-T, and have a growing suspicion I could maybe neck the hotspot down a little tighter to get a bit more throw. Have any of you succeeded with this, and if so, how??

I know, I know, what kind of nut would want more throw out of his PR-T? Well, me I guess...

When I fire the light up at REALLY close range (like 3-6 inches), I notice a hole in the middle of the beam. That's what started me thinking.

But, in the grand Reno tradition, I'm not touching anything till I hear from the experts.

There's really no room to move anything around in a PR-T. Even if there was, I think the emitter is forced into the optimal position. If you moved the emitter forward a bit the beam should get wider (and would probably degrade in other ways as well). If you move it backward you're going to start spilling light behind the reflector, which obvioulsy doesn't do you much good.

The hole you see up close is required for the best throw. There is no reflecting off the part of the reflector nearest the emitter - thus the hole. But that hole goes away after a few feet, and you have the tightest beam you can get from that reflector. The only way to get rid of the hole up close is to scatter the photons with some LSD or something similar (sandpaper on the lens?) /ubbthreads/images/graemlins/smile.gif - but that'll play hell with your throw. If what you want is the best throw, stop looking at it up close! /ubbthreads/images/graemlins/tongue.gif

Darell says: Don't screw with it, 'cause you aren't likely to get more throw with a "refocus."

Reno,

Look at a turbo head's beam, in close. Some have a serious black hole. I may be wrong but I believe this is a result of the dead space between the light source (the die) and the start of the reflector itself. The only way to avoid it, if I am correct, would be to have the reflective surface come all the way to the light source with no void. With these types of reflectors, the beam doesn't completely converge until some distance from the light source. Some of the "big guns" I have seen have such a big hole in close that measuring lux at one meter would really do them an injustice; seeing that there is still a hole at one meter!

If you want to increase the throw of your PR-T, you can play with removing some of the reflector's rear face so it will sit down deeper if slightly elevating the reflector doesn't improve the beam. I am sure that the ideal allignment of LED to reflector could be off as much as .010" from one example to the next but I did try to design in what I felt was the optimal "set" on the Lux III or 1W.

Another thing you can do which will likely improve the throw is to remove the reflective coating and then polish the reflector perfectly smooth and to a high shine. This will tighten the beam noticibly and project the die image in a sharper manner.

Anyway, I think I'm right in what I said but then again, I have been wrong so many times in the past............ Take this with a heap of sodium cloride.