Re: mCree XR-E ( & Seoul P4) lights, reflectors and notes...
The Cree chip, EZ1000 used in their own package, the XR-E LED is also being used by other LED manufacturers. The Seoul P4 is one such LED and it has great market potental based on its more familiar package geometry as well as a lambertian distribution of light output. Like previous generation Seoul LED's in similar packaging, the image location is below that of the similar Luxeon and optics must be adjusted accordingly. It's cool now to have two options with great light output!
Some new Seoul P4 hosts:
I think a good example of the differences can be viewed in the beam shot below where an Aleph 3 with XR-E and DB917 is top and an Aleph 3 with Seoul P4 is bottom image. (The A3-XR-E has a restricted spill diameter compared to the A3-P4 due to a deep Ti bezel ring. Had I been paying attention to such matters, I would have had stock bezel rings on both lights for the comparison.
The Cree XR-E is likely to loose much of its steam due to the more friendly P4 but I think it still has its own niche and due to exploiting its narrower viewing angle and low image location. That is to say in a small diameter reflector, you can shape a Cree's beam in manners not available from the other LED's. As an example of this, the beam shot below has two similar sized lights, top is a XR19-C and bottom is a PD with Seoul P4. The images were taken on different days but with the same manual setting on the camera and light position and target are identical. In the case of the XR19, the camera was probably a foot closer to the light.
I am starting to compile some images and observations on my web site,
HERE.
I have decided for a number of reasons to go forward with the Ti 27 heads hosting the Seoul P4 instead of the XR-E. The Seoul puts more of its light off axis where it is available for the reflector to collimate it and I feel the 27 reflector is well suited for this and likely a bit more appropriate for most users. The Ti 27 head was originally intended as host to a Luxeon LED and it is an easier modification to have it host the Seoul compared to the Cree XR-E. The Seoul also presents better on a white wall with a smoother transition from spot to spill.
Below is a wall shot comparison between an XR27-C (Right) and a S27-C (Left)
There is a difference between these two lights but the pros and cons are mostly of a subjective nature, IMHO. I had to decide to build with one or the other LED as going with both is too much to contend with. I like the greater difference between the XR19 and S27 beams and feel the two compliment each other better than if I had kept with the Cree XR-E in the 27. :shrug:
Although Seoul claims a higher flux from the EZ1000 than Cree does, it is difficult for any of us to know where the truth may really lie. It may be that Seoul has a more efficient phosphor package than Cree or it may be that the method of measuring and picking a number to claim is different. Kind of tough taking the same die and hosting it in the two packages for a real comparison! :green:
At any rate, the Seoul is the real deal and it uses the wonderful EZ1000 as its core.
I have modded both an Aleph 3 and a HD45 with Seoul P4's and DB917 converters and both of these lights clear the 10k lux barrier.
In general, aside from the Seoul slug being anode and in need of isolation from the electrical circuit, the only other issue in replacing a Luxeon with a Seoul is the need to elevate the Seoul relative to the optic. From a number of bench tests I have done, it looks like about a .030" difference compared to the Luxeon III Jokers. At anyrate, I have built a number of different lights and mods using this adjustment and the resulting beam has been very acceptable if not optimal in lux. I came up with the same offset using a large aspherical lens infront of both the LuxIII and Seoul P4.
In regards to the Aleph system, Wayne and I have come up with some simple solutions that will be detailed further by him and when he chooses to do so. A proper LE hosting a P4 can be screwed into an Aleph 1 or Aleph3 requiring no modification to the reflector or head. In the case of an Aleph 2 with the McR-20, .030" needs to be removed from the rear of the reflector. I do have both McR-20-S and McR-27-S reflectors on order and will get them first of the year. I plan to switch over with the remaining aluminum PD sets as well as the 27LT to the Seoul P4. I have plenty of U flux bin LED's for these lights and all I need is time and reflectors to go about it. I don't want to wait on the Ti S27 heads and I have already modified existing 27 mm reflectors for some of these and am in process of building out some of the heads. As soon as I get some Ti C or PD power paks in, I will be able to once again offer some XR19's as well as the S27's.
With Cree at the core, I guess the S27 is still a mCree light or is it a McSeoul light? Or does it matter a stinking bit?!?! :nana:
