Variable frost. Better than a donut hole?

Everyone is familiar with the "donut hole" that results from "focusing" flashlights that move the bulb position.

But we know that with a fixed bulb we can change the nature of a light from spot to flood by switching from clear to semi-frosted to heavily frosted bulbs.

What about use of a variable-frost mechanism? What I have in mind is a tube of glass with an increasing gradient of frosting over a range of an inch or so. Using a clear bulb, leave it in position but move the frost-tube to shield the bulb at various depths....

I'm not sure how the artifacts would compare but it might be a superior means of providing a de-focusable light.

Such a tube should be producible by slowly plunging into a frosting medium so that the first portion is frosted longest, etc... A pyrex test-tube could furnish the raw material.

I wish I had the time to play with this. Has this idea been tried?

Something like this was done with red-white-green torches, where a coloured filter is slid around or in front of the bulb.

Seen some fascinating and ingenious mechanisms of this type on vintage military or railway torches on eBay.

http://www.surefire.com/maxexp/main/co_disp/displ/carfnbr/249/sesent/00

surefire has that, my concern is that frosting causes a lot of lost light energy, most people are pushing for lumens and an inefficient bulb from an incan is already struggling to produce lumens, best to get multiple lights. That is the CPF spirit anyways right?

65535 said:

http://www.surefire.com/maxexp/main/co_disp/displ/carfnbr/249/sesent/00

surefire has that, my concern is that frosting causes a lot of lost light energy, most people are pushing for lumens and an inefficient bulb from an incan is already struggling to produce lumens, best to get multiple lights. That is the CPF spirit anyways right?

Click to expand...

True, but their diffusers are on/off. This is more a way to address a variable de-focusing system such as Mags have. Which I think is a pretty good idea except for the fact that it leaves a dark spot right in the center of what you're trying to light up.

interested in your concept, i KLUDGED a hunk of flexable diffusion around the bulb item itself in a normal mag, with a normal bulb. set it for "wide" and there is still a hole, Arggg, so what is the reflector viewing that makes the hole there optically?

i use the ol emitter alignment trick to see what the hole was, by viewing into the reflector, still cant figure it. hmm its reflecting the chrome bulb screw thing, weird because it is reflective too, so it must be viewing the inside of the cam tube below it, so there is the black hole.

difusion would have to put light where black (or base) was, so heavier diffusion.
then i tossed a more flooding type of diffusion in, and no more doughnut hole at all. cool.

so assuming you just wanted to repatent a new Mag concept so you can sue them later. it seems that a plastic tube with a clear bottom and more diffuse top, that rode up and down with the cam mechanism (attached to reflector itself) would do what your saying.

the tube with gradient diffusion would have a place where it ended, at the top of the bulb adding in a bit more artifacts from the tube.

diffusion ( or optics) would have to be directional in such a way as to be very specialised,
take the gradient diffusion tube,
you want a Clear base, so it does not effect throw postition
BUT you need to get the light TO that same lower base location when wide, to put light in the right location.
there is linear diffusion used in LCD screen backlights, duh i have some, let me try that.

Duel Cam? reflector going up and the diffusion going down?

i say Possible. with issues amasing out of box thinking there.

darn, that was a mess, to "lighttube" the light into the black hole, puts the exit of the "lightube" at the same place where you need it to be totally clear.

light would have to pass through it cleanly horizontal to the tube, "through the film" unobstructed.
then when the light moves to the defraction location it has to be transmitted down the film length, to the same location where it was clear horizontally .

I tried it in a maglite using a piece of chemistry (glass) tubing that had been etched. It wasn't a progessive frost, just spot, and frost. I used the screw in/ out system on the maglite to do it... fix the bulb, spring outside the lamp pedistal, lop off the cam, enlarge the hole. I didn't like it because I really had to hack a chunk out of the center of the reflector to get it to fit...There isn't enough cam action in the maglite to do it... what you end up with is having to move the lamp and reflector down into the tube...

VidPro said:

interested in your concept, i KLUDGED a hunk of flexable diffusion around the bulb item itself in a normal mag, with a normal bulb. set it for "wide" and there is still a hole

Click to expand...

Hmmm. Actually you'd want to keep the bulb filament fixed at the focal point, not move the bulb at all. Start with a perfect spot/throw. Transition toward flood accomplished entirely by the diffuser.

Abinok - thanks for trying!

Nubo said:

Hmmm. Actually you'd want to keep the bulb filament fixed at the focal point, not move the bulb at all. Start with a perfect spot/throw. Transition toward flood accomplished entirely by the diffuser.

Abinok - thanks for trying!

Click to expand...

ohh, i read your OP better, and understand.
I thought you were going for fixing Just the wide when wide, gee that would have been easier .