No apparent change in hotspot for Fenix Bc35r after dedoming/shaving XHP50

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Namelessusername
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No apparent change in hotspot for Fenix Bc35r after dedoming/shaving XHP50

Could it be that if Fenix bc35r has a special reflector with half scooped and other half parabolic reflector with a horizontal lens molded at the top of the plastic glass then dedoming doesn’t work in this case? It somewhat seemed like trying it against the fence 10 metres away the fence seemed to be better illuminated while having a bit less foreground lighting which is better for distance vision after dedoming .

Edited by: Namelessusername on 03/04/2021 - 11:14
Namelessusername
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https://ibb.co/G5Ptpx2
Hotspot 60cm from the wall. In person there is almost no classical hotspot at all, only short horizontal line 5cm from the wall.

EasyB
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The difference in beam size from dedoming is not dramatic. It should be roughly a factor of 2 in beam area which equates to only 1.4x difference in beam diameter.

As you suspect, that weird reflector could also make the difference less apparent.

Namelessusername
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EasyB wrote:
The difference in beam size from dedoming is not dramatic. It should be roughly a factor of 2 in beam area which equates to only 1.4x difference in beam diameter.

As you suspect, that weird reflector could also make the difference less apparent.

Probably will use the dedomed one just to be safe than sorry for possibly increased throw even if the surface looks a bit rough since constant prossure on the blade while cutting might suddenly detach the dome together with the phosphor.

Chicken Drumstick
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The only way to see a difference is measurements really. Do you have a way of measuring throw?

If not a camera with full manual control should allow you to take a before and after control shot. So long as the camera settings, location and distances are the same, you should be able to see if there has been a change.

jon_slider
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Namelessusername wrote:
there is almost no classical hotspot at all

that looks like it might be a type of TiR lens (Total Internal Reflection). It collects all the light from the LED and shapes the beam. In this case it creates a horizontal cutoff, so that the light can be used on a road bike, without blinding oncoming drivers.

dedoming the LED lowers CCT (color temperature)
it also lowers the Tint, aka lower duv, aka less green tint

but since it is not a light with a conventional reflector and exposed LED, I dont think a change in throw is likely to be noticeable through that Lens..

the banding in the beam photo suggests PWM… you could verify by waving the light.. to see if it shows dots, like the light on the right:

In practice, PWM would be turning the light on and off, usually too fast to be noticeable visually. However, PWM can create a freeze frame effect in rain or snow.. Not necessarily bad, best not to be on the bike at that time anyway. A few people are sensitive to PWM, and they get eyestrain and headaches.. from the pulsing light..

Namelessusername
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Chicken Drumstick wrote:
The only way to see a difference is measurements really. Do you have a way of measuring throw?

If not a camera with full manual control should allow you to take a before and after control shot. So long as the camera settings, location and distances are the same, you should be able to see if there has been a change.

Without proper equipment and measurement method there is no way to tell since with a Light Spectrum Pro Evo numbers are constantly jumping all over the place.
Domed was on 1000lm setting was 2400Lux@60cm.
Sliced with a rough silicone surface was 1800Lux@60cm.
Sliced with a razor resulting in smoother surface (could have been better if the MPCB suddenly didn’t start to move for some reason) was 2800Lux@60cm.

Namelessusername
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jon_slider wrote:
Namelessusername wrote:
there is almost no classical hotspot at all

that looks like it might be a type of TiR lens (Total Internal Reflection). It collects all the light from the LED and shapes the beam. In this case it creates a horizontal cutoff, so that the light can be used on a road bike, without blinding oncoming drivers.

dedoming the LED lowers CCT (color temperature)
it also lowers the Tint, aka lower duv, aka less green tint

but since it is not a light with a conventional reflector and exposed LED, I dont think a change in throw is likely to be noticeable through that Lens..

the banding in the beam photo suggests PWM… you could verify by waving the light.. to see if it shows dots, like the light on the right:

In practice, PWM would be turning the light on and off, usually too fast to be noticeable visually. However, PWM can create a freeze frame effect in rain or snow.. Not necessarily bad, best not to be on the bike at that time anyway. A few people are sensitive to PWM, and they get eyestrain and headaches.. from the pulsing light..

Not sure if it’s a tir since the reflector and curved lens at the top can be seen. It’s meant to create cut-off with a wide uniform beam pattern which should gradually decrease in brightness from top to bottom in order to reduce foreground lighting and improve the distance vision while at the same time being able to see the side of the road better at the distance compared to regular circular/symmetrical beam.
Not sure how does the Fenix bc35r and bc25r compare to Busch and Mueller Iq2 which is said to be using some sort of a prism in terms of efficiency but in terms of uniform beam spread Busch and Mueller was better. Had no other choice but to use Fenix since I wasn’t sure about the modability of Busch and Mueller and it is offered only in cool white (Olson Black Flat). Fenix bc35r and bc25r already was available with NW 4500k emitters which I was able to change for 3200k 90cri and 95cri for better night vision due to higher red content, less glare and better transmission trough the lens of the eye compared to blue wavelengths.

I think it’s not a PWM since there is no flickering trough camera. Those are just a stray lines formed mainly by upper part of the lens lens and probably somewhat by a reflector.

Namelessusername
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Domed 1000lm setting. https://ibb.co/album/b7Bz0D
Dedomed 1000lm setting.
https://ibb.co/album/mbmxjq
In the second picture the light seems to be aimed higher so it’s not a reliable way to tell the difference anymore.

Namelessusername
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Seems like reflowing sliced SST-20 in a Fenix bc25r made the upper part/line focused by lens of the asymetrical layered beam narrower and brighter, while the central hotspot turned from triangular to horizontal short line. Still had to attach some black almost non-reflective baffle/hood made out of thick paper perpendicular to the reflector to act as a near field/foreground limiter (similar to deep set recessed reflector headlights with black ledges at the bottom and top found in cars with reflector headlights nowadays).