Optimal optics angle for MTB light (4x CREE XR-E)

[kubajs]

Hi guys,
I'd like to build my own 4x CREE XR-E Q5 or R2 light powered by 1A, 19.2V.

Please, could you recommend me optimal optics angles for that?
I'd like to use it for MTB riding.

I'm thinking about something like 3 x 10° and 1 x 25°.
Maybe 3x14-15° and 1x25 could be better?

Or would you recommend me to use some oval optics (e.g. 25x8°)?

Thanks for any recommendations and advices.

 

[trout]

Welcome to CPF


That is a tough question cos every one likes their cocktail different.
If you search threw you will find every permutation of optic chioce.

some beam shots here
http://www.candlepowerforums.com/vb/showthread.php?t=185665

I am building a 5 or 6 led light and am using the square ledil optics
so am going to start with this setup

oval / smooth spot / real spot / real spot / smooth spot / oval

or if it is 5 then the same but onle 1 real spot in the centre.

but I wont know what it is like untill the optics arrive

Brum has a group buy going on in the market place.

 

[HEY HEY ITS HENDO]

Hey kubajs :thumbsup::welcome::wave:

open terrain, straight tracks a focused beam is good
but twisty wooded track, floodlight beam is best
1 x 10, 2 x 15. 1 x 25

 

[kubajs]

Thanks guys,

I just have an experience with 1 Fenix L2D light. That's ok for roads but a little bit insufficient for terrain. Ride with this light in pure terrain is something like ride through castle of fear (because of the small spot angle) :laughing:.
I guess the 4 CREE in the combination 10 - 15 - 15 - 25° must be awesome, especially when powered by 1A .

Do you have any preferences what optics to use (from what manufacturer) or they mostly provide very similar results?

 

[SemiMan]

I would suggest reflectors or mixing reflectors with optics. The lack of spill with optics is troublesome.

Semiman

 

[chris_m]

They don't seem to have many other fans round here, but I really like the Cree 8 degree optic. The main beam is nice and narrow to give plenty of throw, but crucially there is a significant amount of spill outside the main beam. I just use those in all my lights, and don't think anything else would give a much improved light pattern for what I do.

 

[ifor powell]

The answer will depend on which optics. They are not all the same.

With the Ledils I have a 3*2 array with 4 RS and 2 ovals in the middle which is good for the big headlamp I have for night Orientearing. The ovals push out the sides to give better periferal vision without wasting light up and down. On a MTB you want to cover just in front of the weel at close range as well. I have not gone and tried my 6 on my mtb yet so don't know if I have a hole or not. If needs be I have a couple of the diffuses which are curently in a double on my road bike for going around town. Those would be my first replacment if the ovals are not good. I also have some smooth spots I could swap in for the real spots which will give more spill as well, simillar to Chris with his Cree spots. I like the fact that I can pick and mix easaly with the Ledils and the way I have them setup.

Ifor

 

[kubajs]

My another idea is to use not 4 CREEs in series powered by 1A but to use 8 of them (2 parallel branches with 4 in series - 1 branch = 500mA).
With this solution i might use for example 6x spot optics and 2x floodlights.
The spot optics all together could keep suitable angles in the lamp.
So the light would have more bright points. In opposite it could be a little bit distracting.
But I believe 6 spot optics appropriately combined together might be sufficient for such a light and it would offer very long range and wide range light together.

What do you think about that solution?

 

[Martin]

If you go for narrow optics (4..10 deg) and add a diffuser lid or cap (like the Petzl Myo headlamps), you can have the best of both worlds.
A diffuser with a vertical pattern will diffuse mostly horizontally, this is preferable.

 

[znomit]

They don't seem to have many other fans round here, but I really like the Cree 8 degree optic.

Its a nice optic for the road(built a few lights around them, 10$ for 10 shipped from kai) but too narrow for the trails.

I like the OPTX optics because you can swap diffusers to find something you like. Im thinking of redoing my MTB light to make it a little wider, and replaced the optics which are a little worse for wear after being cleaned with alcohol(seems its just for drinking).

 

[chris_m]

With the Ledils I have a 3*2 array with 4 RS and 2 ovals in the middle which is good for the big headlamp I have for night Orientearing.

So you've got a 6 LED setup in your new orienteering lamp? I thought my 4 LED job was state of the art - no wonder you're performing better (though just seeing you running from the start at the last event got me worried as you seem to be able to run again!)

 

[ifor powell]

You would not be so worried if you saw me running at the finish Chris. I have improved a bit but I am still a long way off from being fixed, the new light is enfusing me a bit though.

The 6 is good for the light but it's fairly heavy weight. it's got enough heatsinking to be ok on my kitchen table but thats too mush for running or biking. I can only mount it comfortably with the old Silva plastic head frame so there is no way to use it as a helmet mount on the bike though it would work well as a bar mount.

I am working on a small light weight 4 hoping to get the head and driver all intergrated and have it fitable on a old petzel headband this will be far more suitable for AR.

Ifor