White paint to save wasted light?

[jimmyh]

I was given a really cool focusable flood to throw flashlight. 18650/XML made by SIPIK. Anyway, when the lens is pulled all the way out to throw, the light not hitting the lens is wasted - the walls are black.

My first thought is that the extra light would be useful (even if not focused into the spot), and that it would benefit from white paint on the walls to salvage some of the light.

Has anyone played with this? Are there any practical issues with binding up the sliding or paint falling off? Is the "free" light off center generally welcomed or disliked?

Cheers,
Jimmy

 

[Esko]

:welcome: jimmyh,

Painting the insides white would increase the light output. However, the extra light wouldn't be too useful. It would go to the spill, causing rings and other artifacts and perhaps also glare.

If you want the maximum throw, aspheric lens is the right choice. You'll lose a rather big part of the output but the light that goes out will be very consentrated. There is also very little spill (if it is a good lens) which is good if you want to preserve night vision or you don't want to draw attention to you or, well, you just don't want to have spill. However, if you want both throw and spill you should choose a large reflector. You will lose some throw but you will also have some useful spill and the total output is higher.

 

[jimmyh]

Yeah, I understand the physics and get that it'd be all spill. It does use an aspheric lens and focuses quite nicely (the beam pattern is a perfect image of the die).

My first thought was that wasted light is bad, and that free spill is worth something - but I'm not sure how true that is when you can just put the flashlight into flood mode anyway. And there's the issue you mentioned of extra visibility to out of beam viewers.

I guess most of the question boils down to "Free spill good or bad?", but I'm also interested in hearing any other thoughts people have on the matter, including practical difficulties.

 

[Vortus]

Or some thin chrome tape on the inside if it wont hinder the movement