Enderman, what reflector coating did you choose?
It seems yes.Mea culpa…
Haha yeah, there is like 5mm between the bottom of the reflector and aluminum plate 
Aluminum.
Protected silver was way too expensive and also delicate.
Rhodium is worse than aluminum and only necessary for stuff like short arcs.
With MgF2 overcoat?
Out of curiosity how much would silver cost?
“We generally do not coat with silver. It’s somewhat problematic to coat and even with an overcoat it isn’t very durable. Silver is very active in a normal air environment. The price would be roughly twice that of a single piece with aluminum. ”
-Phoenix Electroforms
I’m not sure if mine is overcoated, it probably is just plain aluminum. I didn’t ask for any special additional coatings since aluminum is pretty durable as long as there isn’t a ton of UV like from an arc lamp.
On Optiforms I see that their MgF2 has a little higher reflectivity than their protected alu (they don’t do unprotected):
https://www.optiforms.com/optical-coatings/protected-aluminum-aluminum-quartz/
~93.5% vs ~90%.
Elsewhere on BLF I saw comments that uncoated alu oxidises quickly and what we can really expect is 85%.
Could you shed some light on it?
No idea, I haven’t used Optiforms.
I wasn’t going to pay double to get my reflector from them.
This is the info that Phoenix gave me a while ago:
“Silver is more reflective in the visible than rhodium. We have many customers do a google search for the most reflective materials. Silver always rises to the top. We recommend vacuum deposited aluminum. It is far less expensive. It is less reactive in the atmosphere. It has a reflectance in the 92-95% range which is acceptable for just about anything other than sensitive measuring equipment.
We do provide vacuum deposited aluminum with a SiO2 overcoat as well as rhodium.”
Maybe the coating I got is AlSiO2.
EDIT- yeah just checked the specs document, it is SiO2 coated aluminum.
It says “PA17.02AQ” on my invoice.
Thanks
I just found your build threads on your so called “flashlight” builds Enderman, I must say I greatly admire your engineering skills and workmanship on your projects. Seriously great work. 
+1 …… :+1: … He quiet frankly amazes me with the things he comes up with.
Better add me here as well though he does know anyway. 
Hey thanks guys
Here are a few overexposed beamshots which look really cool
And here are some which aren’t overexposed. The sky wasn’t super dark because it’s summer and it was early morning (like 2am).
Still waiting for my custom CFT90 driver to arrive, can’t wait to see what 5x more lumens will do to the beam!
I have to admit, focusing this thing is a pain even with the three-screw system, part of the reason being the small LED and huge angle off-axis (like 85 degrees) that most of the reflector collects light at.
Haven’t been able to get more than 7.5mcd yet which is a bit disappointing.
I will be attempting to focus it better and measure again in one or two weeks, I’ll let you guys know if I get an improvement.
This optic system is great for getting extremely high luminous efficiency, collecting close to 90% of all the lumens into the beam and spot (more than any other type of optic!) so the CFT90 or other high output LED (dedomed XHP70.2? 
) is probably a better fit for this type of flashlight.
I don’t recommend this type of retro-reflector for anyone making a superthrower, unless you use a long focal length mirror similar to a telescope, in which case it will behave more like a lens and lose the high efficiency.
Still glad that this set a new record for LED searchlights/flashlights as far as I know there isn’t any other LED light that can throw further, not even LED lighthouses.
I think your friend you’re building one for is ready to come pick it up
Looking forward to seeing the CFT-90 in action!
Same, I think this upgrade will make the whole project worth it, despite lower than expected candela.
It should also make it easier to focus thanks to the larger die, so who knows, it might get higher than 7.5M no promises though…
Nice pics!
Have you tried varriing the height of the LED?
Genial :+1:
What is a reasonable price for the CFT-90 LED? I heard some rumours about 70-100 Euros/Dollars, so probably something you’d better handle with velvet gloves on.