Reflector choice: McR or IMS

Hi,

I am currently building a new light for biking in the woods. For this I plan to use square aluminium tubes (as initialy suggested by the great guide of nightrider). I now have to choose the optic/reflector. I have a 20mm square section so that both IMS20 and Mcr19 would fit.

But which one should I choose? I had in my hands IMS17 and Mcr17, and of course plastic of IMS is not so high-quality-looking as McR, but it is rather an impression.
Is there any more precise comparison of those two types of reflectors?

I tried to make a short comparison list:

• price is 5$ for IMS and 15$ for McR (so, instead of 2 Mcr+Cree, I could get 4IMS+Cree, for approximately the same price. So I could get twice the power or the autonomy :naughty: )
• I guess the amount of lost light must be greater with plastic but is it so important?
• is durability more important with metal. Or conversely, is IMS plastic sensible to scratch?
• The issue of positionning the led (CREE) is also important: it seems that MCR exist in XR version you only have to put on the cree, but I can also sand the ims20 and enlarge the hole (as I did for the ims17 in my PT-EOS).

Maybe I should also consider optics (carclo, Cree, fraen... the choice seems all the more difficult! :thinking: ).
Can you help me in this comparison and choosing.

Using either of the reflectors (non XR-versions) would require you sand about 1mm from the back for the Cree dome and metal ring to fit for nice focus.

I have done so with great succes. However: The (plastic) IMS can (and will) melt.
Since the ring around the dome is metal, it will suck up heat from the die and will pass it on to the IMS. At first the coating will start to peel off, and later the reflector itself will just cripple... This was not an issue with the Lux emitters because there the heat would go ONLY to the heatsink.

I do recommend using the McR, as the Orange-Peel structure gives it a nice beam.
The aluminum reflector can also assist in heatsinking the heat "stored" in the metal ring.
(note: apart from the heat-issue, the IMS is still a great reflector-series)

If you wanna go with optics, good also.
I've used the Cree-optic made for the Cree.
Beam is not bad, but you can't bet the low price (4bucks ea ?)

This optic will not fit in all small lights because the optic is quite high at 15mm,
but you might get it to work in your bike-light.

I have some info regarding these optics, let me know if you had not
seen these yet and I will dig it up for you.

Cheers man !

EDIT1: The IMS17 "replacement" in the McR-series would be the McR-18

Thanks bombelman,
This melting issue might be a real problem and has to be considered if I want to think at a rather long term.

Maybe this in conjuction with the focussing isue will make me choose this alternate solution: 4McR (instead of 4IMS or 2 McR)

btw, check out these optics here.
http://candlepowerforums.com/vb/showthread.php?t=139705

Still a few available.

i know its short and sweet... but after mult. months of researching this very same topic... I have found that McR > IMS

bombelman said:

btw, check out these optics here.
http://candlepowerforums.com/vb/showthread.php?t=139705

Still a few available.

Click to expand...

Thank you for the link: this might be a still better option.