I got the Canon lens I ordered off ebay. Took it completely apart, there are two optics that can work, the largest one is the top outermost element from the lens and probably the one I’ll use. It focuses cleaner and from a bit further thatn the Z1 optic, gives a pretty tight hot spot in combination with the 7” lens and as expected, virtually eliminates spill. The hot spot with the 7” lens alone is just insanely small so throw would be absolute without the second lens, using a second lens to collimate light into the larger lens will give more output, brighter hot spot albeit larger and with less overall throw. Will have to do the build and compare the two options to see what would be the best way to set it up.
Dale, forgive me if I’m telling you something you already know, but when you add a precollimator lens, the beam lux doesn’t necessarily go down significantly when the beam size increases. For example, below are my measurements from the thread I linked above, for a UF-1504 with XPL HI V2 1A.
Stock light without pre collimator lens.
11,800 lux at 6.05m: 432,000 cd
approximate beam size: 20cm x 20cm
With pre collimator lens
11,340 lux at 6.05m: 415,000cd
approximate beam size: 29cm x 29cm
While that might seem relatively insignificant, you ARE talking about a difference of 20cm to 29 cm. The way this one is looking, it will be a much more drastic difference than that.
What if that difference was from 29cm to 0.5cm?
At any rate, I’ll have to get busy and make the lens mount plate before I can really start figuring any of this out. It won’t be all that difficult to make an attachment to allow the pre-collimator lens to be added or subtracted. Well, I’ll plan on it going in. lol
One thing that might be happening is that when you put in the pre collimator lens it changes the apparent position of the LED, so the big lens becomes out of focus.
Wow! If I could increase the size of the spot that much while only losing such a tiny fraction of the lux value, I’d take that any day! With a pre-collimator, you’re more than doubling the amount of light within the hot-spot!
Right David, that’s the whole purpose of using the pre-collimator lens, to gain back the lost lumens.
Easy, I see what you’re saying but I’ve been playing around with the combinations hand held, fully adjusting focal distances for each lens as I look for the optimal distance. I mounted the light on my tripod, so I had a lens in each hand to easily do the tweaking.
Edit: Keeping in mind my Z1 has a SBT-70 mounted. It’s a round die and quite large. The Z1 aspheric put’s a pretty big hot spot on the wall, even at 10’. The 7” lens is ridiculous! With no pre-collimation it’s about 3/8” at the same 10’, with the Canon lens pre-collimating at the optimal distances the hot spot is about 6” at 10’ as compared to 10-12” from the Z1 aspheric. And the Canon lens puts a brighter hot spot on the wall, clearer, with the wires across the phosphor plainly visible as well as the blue edging around the contact plates that is emitter makes. So at a 10’ testing range, the difference in hot spot size is from ~0.365” to 6”. That’s a LOT of difference! So lux or downrange throw would, it would stand to reason, also be affected by a great deal.
I’ll try some other things and see what’s shaking…
I see. Your big lens has a smaller diameter to focal length ratio than what I have experience with, so things may be behaving differently than I’m expecting.
When you say the precollimator is at the optimal distance, do you mean that the light cone is just filling the large 7” lens? If so, you might try significantly overfilling the 7” lens. With the precollimator very close to the LED, the beam should be close to the same size as without the precollimator. Then I would start moving the precollimator lens away from the LED until the beam lux is 90% of the without-precollimator lux. At this point hopefully the beam size is twice or three times the original beam area.
Yes, I found that with this Canon glass about 1-1/2” from the emitter and the 7” glass at the ~16” focal length the Canon glass is “overfilling” the bigger lens and the hot spot is pretty intense. I tried it with my Convoy L6 and de-domed XP-G2 and it’s pretty amazing, especially with the big lens alone, I seriously feel like I could start fires with this thing! 
Edit: Here’s the construction diagram of the Canon EF-S 17-85mm lens I disassembled to get this “lens”. As it turns out, it’s the last 3 lenses put together into one “element”. The housing is plastic, the retaining cover on the back has 3 spot welds holding the pieces together, so if I try to disassemble these 3 looking for more gains I probably won’t be able to reassemble this element. Ah the joys of thinking outside the box! 
It’s the 3 largest diameter pieces. The green shaded piece at the mount side of the lens is an aspheric. Gotta check that one out independently…
Geez - that lens looks awesome.
Can’t wait to see some pictures of the build!
Playing around, free hand, light clamped on my tripod…. this is the SBT-70 big die by the way (I, uh, braignfahrtensteined again and quoted a 3/8” hot spot which was of course the de-domed XP-G2. sorry. Cause me as much or more grief as y’all, I assure you.)
[braignfahrtenstein= brain fart of Frankensteinian proportion)
The Z1, open topped, with the Canon glass in front at focus point…
Z1, open topped, with the 7” Condenser lens in front at focus point…
Z1, open topped, with the Canon glass slightly overfilling the 7” Condenser…
Yes, I know, not properly oriented and all that. I had the camera sitting on a box with a 13 second timer, holding the Canon glass in front of the tripod mounted light while adjusting position of the 7” glass (which is difficult to hold one handed) for focus. The general result speaks for itself showing increased intensity and decreased light loss to the room. 
Now I just have to build it. 
The photo’s are actually somewhat misleading as the actual hot spot is considerably smaller to the eye than what the camera was able to capture. The intensity blows out the area around the hot spot in the sensor.
The camera’s auto system also adjusted the exposure according to the intensity, which is partially why the bed and surrounding room look so dark in the third pic… can’t man the camera and two floating lenses at the same time.
FWIW:
1st shot, 1/30th second at f/2.0 ISO 500
2nd shot, 1/100th second at f/2.0 ISO 400
3rd shot, 1/30th second at f/2.2 ISO 80
Canon S90 on a 13 second timer, 3 shots, I picked the best of the 3 in each instance. (I didn’t necessarily get into position in time. lol)
This is getting very interesting. 
Just to clarify, the first two pictures have only 1 lens, while the third picture has a precollimator in place? Nice, put all that wasted light into the hotspot.
Correct. The 3rd picture has both lenses focusing the light and it clearly shows in the camera’s chosen settings. I could probably set it all up and shoot it in our game room at 5M at my meter and get an approximation of what kind of lux to expect…
Notice the clarity of the side light coming through the Canon lens. This is a very high quality lens of course, coming out of a $600 camera lens. So, together I have some $87 in the two lenses even before starting a build. (I have a bag of parts on some other lenses to play with of course from the torn down EF-S 17-85mm IS lens. )
Wow, I have seen less complicated optics in rifle scopes.
Be careful… don’t burn a hole in the wall. :smiling_imp:
I’m thinking “singularity” might be a good name for this cosmic event, meteor, nova, etc. being already taken.
Wait… etc. is taken? Oh man! THAT is what I was gonna name MY light! :person_facepalming:
