Don’t forget that the LED itself has to sit flush on the board. The slightest bit of “float” (ie, too much solder underneath) raises up the LED and you’ll be cutting unevenly at best, cutting too low at worst.
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I’m surprised this is mentioned so rarely in dedoming discussions. When I do a traditional slice on an LED, I reflow it to a specific MCPCB with pressure from tweezers so it’s at exactly the same height every time. That’s the only way to be consistent about slicing height with a guide like a feeler gauge.
More emitters measured. All emitters behave about the same.
Emitter, CCT measured, duv measured
519A 2700k domed, 2660k, 0.0007
519A 2700k 1.4mm slice, 2564k, –0.0005
519A 2700k 1.2mm slice, 2445k, –0.0007
519A 2700k 1.0mm slice, 2273k, –0.0009
519A 2700k dedomed, 2138k, –0.0019
519A 3000k domed, 2993k, –0.0003
519A 3000k 1.4mm slice, 2907k, –0.0014
519A 3000k 1.2mm slice, 2770k, –0.0018
519A 3000k 1.0mm slice, 2607k, –0.0023
519A 3000k dedomed, 2388k, –0.0037
519A 3500k domed, 3423k, 0.0004
519A 3500k 1.4mm slice, 3319k, –0.0012
519A 3500k 1.2mm slice, 3196k, –0.0013
519A 3500k 1.0mm slice, 2999k, –0.0012
519A 3500k dedomed, 2709k, –0.0035
519A 4000k domed, 3779k, 0.0009
519A 4000k 1.4mm slice, 3663k, –0.0014
519A 4000k 1.2mm slice, 3478k, –0.0011
519A 4000k 1.0mm slice, 3329k, –0.0013
519A 4000k dedomed, 3027k, –0.0027
I can get a nice negative duv with CCTs from ~2150k to 5200k.
Happy modding!
FB
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First attempt at image, so I hope it works.
7 CCTs of 519A, all measurements with Opple (so just estimates, but numbers match what I see).
Each with: dome on, 1.4mm slice, 1.2mm slice, 1.0mm slice, dedome
Black = 5700k
Blue = 5000k
Red = 4500k
Orange = 4000k
Green = 3500k
Purple = 3000k
Olive = 2700k
Round = with dome
Square = 1.4mm
Diamond = 1.2mm
Trianlge = 1.0mm
Upside down Triangle = dedome
Also first time with ColorCalculator, so I didn’t know how to add a legend!
Lots of options. Pic your CCT and duv!
FB
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You don’t have to drill into the feeler gauge. Just take the bolt out and you have a hole. The Harbor freight one is 4.99. Thank PointyDogElbows for that one.
I bought a sm405 from Simon, dedomed I’m getting 3200K on 5mA, 3600K on 5A in S2+ OP reflector. This seems a bit high compared to what you are getting, do you think it’s sm405 or did Simon give me sm455 instead?
My sm403 measured ~3000k dedomed. This is at ~500mA.
With dome it measured ~3780k, so it started off a little low.
I’ve only measured (2) sm403 emitters and the other one measured 3860k with dome (never dedomed this one).
Your numbers are a little higher but I’d say it is within the normal tolerance.
Each emitter varies. You have a different emitter source (simon vs clemence)
Different bin (sm405 vs sm403). Different measuring equipment. Different drive currents.
I don’t know what you are using for testing, my I suspect my Opple measures a little low overall.
Happy modding!
FB
Pro-tip: deburring the edges of the hinge hole will give you better results with most cheap sets I’ve tried.
Been trying out sliced 5000K, 4500K and 4000K 519a leds in various lights.
Ran out of 5000K and very low on 4500K. So today was my first time trying out just dedomed 4000K in a light.
It’s …. too orange for me. Probably looks good outside with dark adapted eyes. But for general purpose EDC I often find myself using my lights briefly without dark adapted eyes and indoors. For this the color temp looks way too orange.
Guess it’s time to order more 4500K and 5000K leds. They look great dedomed.
I have 2x 519A 4500K, I installed one in a SC31pro, and sliced it first to 1.44mm. I saw hardly any change in colour temperature, so I went down to 1.26mm (these heights were not really chosen but came from what I had available in various washers). I used a razor blade to make these cuts, most of the dome is off but even at 1.26mm I still see very little change in colour temperature… I don’t have a spectrum measurement device yet so using other LEDs as comparison.
It is nowhere near the SST-20 4000K (IF25A, modified FC11)/Nichia 219C 4000K (Jaxman E2L).
Originally I estimate the temperature was at ca. 4200-4300K, a rough estimate from comparing against the 219b sw45k, SST-20 4000K from the IF25A and from a modified FC11 (using the SST-20 on 16mm PCB from Convoy) and 219C 4000K in the E2L. This conforms to measurements of the 519A 4500K which all appear to be in that same region as my estimate. The SST-20 from Convoy and Sofirn are slightly different to each other, but both are very different from the 519A sliced to 1.26mm (which should be somewhere near 4000K).
Comparing the sliced 519A 4500K 1.26mm to a standard 519A 4500K that I installed in a S2+, I see only a slight lowering of colour temperature.
Could it be that the lowering of the DUV makes it look far more ‘white’ (not as yellow), i.e. gives the impression of being more cool (higher colour temperature) when shining on a white wall or white furniture, even though in colour reproduction of most colours it is similar to a lower temperature?
I need to do some more tests. A quick test in the garden gives various impressions, such as that the shaved 519A may be better than the SST-20 4000K in the IF25A, although it is less easy on the eyes (being more white). It started raining so just a brief impression for now.
What was clear is that the beam is far narrower with the sliced LED in the TIRs that I tried, so that fits with what others say.
I think that is a sensible explanation. I observe the same myself and think there is a reason: if you look at isotherms (lines of constant CCT) on the CIE color chart, they are not orthogonal to the BBL; instead, they are inclined in such a way that lowering the duv corresponds to a shift in the direction of higher CCT.
Agreed, it’s hard to distinguish similar CCTs with different tints. At least for my eyes when comparing flashlights, the CCTs are supposed to be the same, but it doesn’t look that way on a white wall.
Without a measuring device, I think the only way to compare CCTs is with similar tints.
It works exactly that way.
My brain identifies a white wall under the rosy light of the 2000K E21A as white, not as yellow.
Great resource for 519A slicing. However, it would also be awesome if we had candela (or just relative lux readings) at each slice depth.
I’ve seen a detailed candela/throw for domed vs dedomed but not for sliced: https://www.reddit.com/r/flashlight/comments/twiik4/rough_comparison_measurements_of_output_and_throw/
What I’m looking for is minimal CCT drop (i.e. 1.4mm slice probably) but increased candela.
Cool. I had some 5000k from Simon. Two in different lights side by side, one looked great, the other kind of green. I sliced the greener one down to 1mm now it looks great.
I see ~20% drop in output when sliced. This is a rough measurement (celling bounce) and doesn’t seem to matter whether you slice at 1.2 mm or completely dedome.
I also see ~30% reduction in hotspot width when sliced. Again, the difference from any slice to dedome is very small. Once you make the surface flat (slice or dedome) I see this change.
These are estimates and it will depend on reflector or TIR design. The CCT and duv changes are much more noticeable but I do like the tighter beam.
FB
20% drop is still kind of a lot. I don’t dedome or slice unless it’s absolutely necessary. In fact I glued most of dedomed ones back together just to restore their original output lol.
Your ceiling bounce measure could be off. Since the ceiling absorbs some light and a tighter, more energetic hotspot should results in a larger loss due to absorption.
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I’m not sure if a tighter hotspot causes more light to be lost via absorption–the beam profile does nothing to the albedo of your ceiling. In fact, the error is the other way around: when performing a ceiling bounce measurement, a throwy beam will get a higher reading than a floody beam at the same output as more of the light will bounce straight back rather than to an oblique angle that does not reach the sensor.
In TIR-based lights, another consideration is that smaller LES results in higher transmission efficiency, which partially counteracts the loss from dedoming.
I want a cool-neutral quad, would 519A 5000K domed or 5700K half-dedomed look better? They would be similar CCT but the half-dedomed would be more rosy (-0.004 duv?) As I know the lower duv would look better for warm and neutral white but not sure if that’s true for the 4500-5000K range.
I have a single 5700K sliced. CCT is lower than 5000K and duv can be as low as -0.0060 on turbo, but it looks nice. The main point you should consider is that slicing may result in some artifacts under clear optics. 5000K and green AR lens maybe can fit your needs.