Why do SFT40 beams have so much scatter?

by Pure_Helicopter_5386

Pure_Helicopter_5386 3 hours ago
I never loved the SFT40 like everybody else. Part of it is that the more lumen / current but larger emitter tradeoff vs the OSRAMs doesn’t work for me, don’t need brighter spill and if I want a fat beam I’d rather go SBT90.2. But another part is the ‘beam haze’ that always seems to obscure what I’m trying to look at.
Compared to the CULPM1 and the SBT90.2 the SFT40 seems to have a lot more backscatter. If you look at these beamshots from Weerapat you can see how much more defined the SFT40 beam is even though the CULPM1 is higher candela. It seems like it just scatters more as it passes through the air. At first I thought, maybe that’s just the CCT. Blue light scatters more in the atmosphere. CULPM1/SBT90.2 is 5700K while most SFT40 lights seem to use 6500K. Certainly the ones I got. But the SFT40 seems to be uniquely blue even compared to other 6500K emitters. Say the XHP 70.3 HI is not that blue, even though it is also 6500K. It’s way more yellow, not even close.
Once you get into the hundreds of meters and hundreds of thousand of candela, atmospheric effects seem to play a huge role. And the SFT40 seems to have the heaviest scatter of any thrower LED I’ve tried. I haven’t seen one in a TIR optic in person (will be rectified soon), so maybe that changes the equation.
Thoughts?

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