McR-12 Rebel + XP-G?

[Th232]

A quick search didn't come up with anything, so I figure I should ask. How much modification does the McR-12 Rebel need to work with the XP-G, and what's the resulting beam like?

Thanks in advance.

 

[maxspeeds]

The beam is almost all spill. Imagine a huge flood. There is also a huge hotspot that is not much more pronounced than the spill. I enjoyed it for a while, but decided to try a Nichia 136 and I have been very happy with the results.

You may get better results by adjusting the emitter at different focal distances.

 

[Th232]

Thanks for that, pity I'm not looking for an almost entirely spill beam.

For anyone who finds this thread, part of what was throwing my searching off was the keyword "Rebel", Don hasn't made a McR-12-XR, so there's that problem solved. Also found this about the reflector in the LS20, which uses the McR-12 for the main beam. Need to raise it slightly.

Suspect the McR-8 would be the same way then?

 

[fyrstormer]

Any reflector that small is going to produce a very floody beam. In a reflectored light, the focus of the beam will depend mostly on the depth of the reflector vs. the width of the emitter die. The XP-G has the largest emitter die Cree currently sells, unless you count the MC-E, which really is just four separate emitters in a single package. The XP-C has the smallest die, so it should be much easier to focus in a tiny reflector. Alternately, you could use a TIR optic, which will capture and redirect virtually all of the light, instead of letting most of it escape out the front unfocused.

 

[DaFABRICATA]

The Tri-V uses an McR12 coupled with an XPG.
The beam is very nice with a bigger hot-spot and excellent transition to spill.
I personally would not say it is all flood as it does actually throw pretty darn well for a small reflector.
The hot-spot is more noticable up close .

 

[Th232]

Thanks for the info guys, this could be interesting...

I am aware that an XP-G is going to give a relatively unfocussed beam compared to an XP-E or an XP-C, I suppose I should explain what I'm doing here.

I'm taking a swing at using a reflector + aspheric combo as described by Saabluster here. Note that this is different to the usual combination where both elements are rather large, with a horrible result. The reason this result doesn't look horrible is because the light captured by the reflector is sent mainly through the centre of the aspheric, where it's only refracted by a small amount and not sent off in some greatly off-axis angle, as usually happens with a reflector + aspheric combo.

From what I can see the McR-12 and -8 fulfils the first of his criteria quite well, and the third is simply a matter of turning down the reflector to fit. Only query now is how much I have to adjust the reflector height to get it to focus.

On the other hand, if anyone knows of any reflectors that fill these criteria but are also smooth (about the only element I can think of that would improve on the McRs for this application), I'd definitely like to hear about it.

Edit: Why use an XP-G in the first place? It seems to me that the XR-E isn't getting much in the way of improvements from Cree, but the XP-G certainly is. Hence when better binned XP-Gs come out, I can simply swap them instead of having to rework things, as I would if I were using the XR-E.

 

[maxspeeds]

The Tri-V uses an McR12 coupled with an XPG.

I completely forgot that the Tri-V utilizes a McR-12r reflector with an XP-G. DaFABRICATA took some great beamshots that can be seen here: http://www.candlepowerforums.com/vb/showpost.php?p=3353006&postcount=4