Too much hot spot....

I've got a romisen RC-G4 - and I use it for mountain biking at night, but the hot spot is just too much of a spot - are there any way I can make it a bit more floody...

paint the reflector white?
Can you get floody optics for these things?

I tried taking the reflector out, and it was a bit too floody and not terribly bright....

Any suggestion would be gratefully received

thanks

J

Hi, the most SSC P7 lights are nice floody and good for biking.
If you mod the romisen, you can try to various the spacing between Reflector and LED...
painting the reflector is not usefull in my opinion...
greetings, Jens

you might want to take a look at this thread

https://www.candlepowerforums.com/threads/209413&highlight=alternative+to+orange+peel

A quick and easy way is to put Scotch "magic" transparent tape over the lens. It increases the flood quite a bit and reduces the total light output only an insignificant 15% or so. Some people use Glad Press 'n' Seal, which attenuates the light even less. I don't particularly like it since the resulting light pattern isn't round because of the material's texture. It might be an advantage for your application, though, if you orient the material right.

c_c

hyperloop said:

you might want to take a look at this thread

https://www.candlepowerforums.com/threads/209413&highlight=alternative+to+orange+peel

Click to expand...

No offense but that wasn't the best thread to point him to. That is a very poor way to diffuse the beam while still being remotely efficient.

Yeah Im guessing the scotch tape trick will be best for you.

If you can find a PCX (or aspheric) lens with a relatively close focal length, and run it just short the focal length, you can effectively diffuse the hotspot while maintaining most of your efficiency. I did this on a Fenix T1 and the results were superb. The center is still noticably brighter than the rest, but the transition is super smooth and there's a lot more flood now.

this is a good thread about that: https://www.candlepowerforums.com/threads/209607

I use Glad Press n Seal instead of scotch tape.

M@g SSC-P7 without diffuser:


M@g SSC-P7 with diffuser:


M@gs with and without diffuser:

LEDninja said:

I use Glad Press n Seal instead of scotch tape.

M@g SSC-P7 without diffuser:

M@g SSC-P7 with diffuser:

M@gs with and without diffuser:

Click to expand...

Wow, good one! That's one of those now why didn't I think of that ideas. Now I'm off to cut some circles.................

EDIT: weird, I just tried a few pieces of Glad press n seal on my E1B and while it diffuses really well I always come up with a distinctly line shaped beam. There is still a bit of hotspot but the corona is focused into two fairly narrow, perfectly symmetrical beams

Aluminum's reflectivity is pretty high, even matte aluminum is upwards of 80% efficient. Polished aluminum can be as high as 99.6% (This is hard to reach though as pretty much only vapor deposited aluminum can achieve this, same as our coated reflectors) So my sanded and polished reflector is somewhere between 80% and ~95%. I'd say 90% since it's actually pretty polished, the picture makes it look more matte than it really is. And my camera light meter can't discern a difference in brightness from a ceiling bounce test so I'd say it's efficiency is up there.

The only forseeable problem is that the more diffused light going through the glass means more light at greater than incidence angle will be reflected back in, but this is negigible. There is a similar problem with the tape, it may diffuse the light some but you suffer actually more internal reflection problems because there are now 3 different refractive indices to go through, you've got tape, glue and glass. Assuming 15% loss at each layer that's only 61% of light going through. Verses only 2 losses on a sanded reflector which if 90% for the aluminum and 15% for the glass means 76.5% of light going through.

I don't think you should knock sanding and polishing a reflector especially since a similar finish is found on my inova lights, and those engineers scrutinized the design far more than I have.

Spend a couple of bucks and use real LDF.

You will loose a lot fewer lumens and will not get a striated flood.

Google Roscolux diffusion film.

A couple real quick shots of my M60/C2 with and without scotch tape over the lens. They've been adjusted a bit to give a better representation of their actual appearance.

no diffusion



And now with a bit of scotch tape.

qwertyydude said:

. . .The only forseeable problem is that the more diffused light going through the glass means more light at greater than incidence angle will be reflected back in, but this is negigible. There is a similar problem with the tape, it may diffuse the light some but you suffer actually more internal reflection problems because there are now 3 different refractive indices to go through, you've got tape, glue and glass. Assuming 15% loss at each layer that's only 61% of light going through. Verses only 2 losses on a sanded reflector which if 90% for the aluminum and 15% for the glass means 76.5% of light going through. . .

Click to expand...

The 15% light loss I quoted for tape was the total measured with a light box, measuring the same light with and without tape. Other tests have showed the light box (Quickbeam type) to be quite insensitive to focus, so I believe this is a good measurement.

c_c