Convoy S2+ has a challenger ( Nemo )

[ulf]

10 minutes ago, xonefs said:

 

 

Yes. In some cases the blue washes out fluorescence in some scenes that are not super bright, and there is a blue cast in background. It is bright enough in visible that walking around with just the torch I was able to see well walking through a dark forest/swamp boardwalk without any other light source. 

 

I am interested in outdoor nature UVIVF so there will sometimes be things that do not fluoresce well and the visible can wash out things that do fluoresce but not as strongly. I do still like these images. these are some examples where it is problematic (and one thrown in with vine on tree I really like where the visible leak might actually help- but if it didn't reflect visible as much I could probably expose the red fluorescing leaves more). The red leafy plant has a blue cast but I'm pretty sure it only actually fluoresces red, editing can remove it more but it's still there. I think with less visible I would be able to mix strongly and mildly fluorescing things better, where now the visible can reflect and overexpose before getting the milder things. 

 

 

 

 

 

 

 

 

 

 

I was using an Astronomik L3 clip in filter which has a sharp cutoff at 420nm (and a kolari hot mirror on lens) and was still getting too much blue/visible

But how do you know that it is not blue fluorescence that dominates instead of blue leakage?

There are a lot of things that have blue fluorescence and you seam to have quite a lot of blue blocking, below 420nm, on the camera. 

 

At 420nm there is very little light passed from the torch, even with the original configuration.

If you do not like the blue maybe some kind of pale yellow on the lens filter might help, while a Baader U or UG11 might not help if it actually is blue fluorescence.

I do not know, Just speculating.

[xonefs]

I guess I don't know for sure but from just walking around with the light it doesn't seem like it.  It looks like quite a bit of blue/white comes out of the torch and it is so bright and reflects off everything. I would only know better if I had a better filter like those mentioned to put on and see if it improves. Maybe someone here does and can do an AB test between stock filter and ug11/u340 or a baader uvenus or similar. 

 

 

[Andy Perrin]

I think it’s just blue fluorescence you are seeing. Even with my 420nm cut, if I use daylight WB the image is generally very blue. Same if I hold the filter to my eyes and shine the light around. Also my Nemo torch is a filtered torch. 

[xonefs]

That's possible, and would save me a lot of money and hassle trying to fix it if that is the case. I would be curious to see it compared to a u340 or even zwb1.

[Andy Perrin]

Ulf posted the Nemo spectrum at the start of this thread and it clearly has no blue light to filter. While not invincible, Ulf is a pretty good spectrographer, and blue is not at either the far UV or IR ends of the spectrum where most errors seem to occur. I would be astonished to find there is any blue in the beam itself. 
 

The main (shakiest) assumption, in fact, is that the Nemo torch itself has not changed in some way since Ulf measured it. That is, what if your torch differs internally somehow. I doubt that also, but it’s possible. 
—

I think Cadmium had put a schott filter on his Nemo? Maybe he has thoughts. 

[KhanhDam]

7 hours ago, xonefs said:

Hello, I just picked up this light. Mine was Alonefire brand SV13 off Amazon and it is identical to the one pictured (someone was just asking). 

Alonefire SV13 15W 365nm UV Flashlight USB Rechargeable Ultraviolet Blacklight Flashlight Black Light Pet Urine Detector for Resin Curing, Dry Stain, Scorpion with Battery Charger, Battery Included - - Amazon.com

 

looks smaller to me. looking for the one with bigger 26650 batteries. if anyone has a link I'd apprecait eit. 

[Andy Perrin]

This thread was for the Nemo. The Alonefire stuff should go in the Alonefire thread. I didn’t catch that you had an Alonefire when I left the comment above. I’m not sure if Ulf has also tested the Alonefire spectrum.

 

Why not put a UV blocker on your Alonefire and see if the “blue” disappears?

[ulf]

41 minutes ago, KhanhDam said:

Alonefire SV13 15W 365nm UV Flashlight USB Rechargeable Ultraviolet Blacklight Flashlight Black Light Pet Urine Detector for Resin Curing, Dry Stain, Scorpion with Battery Charger, Battery Included - - Amazon.com

 

looks smaller to me. looking for the one with bigger 26650 batteries. if anyone has a link I'd apprecait eit. 

The shape of the aluminium body of this Alonefire SV13 is identical to the "Nemo". It is a 26650 torch.

[xonefs]

1 hour ago, Andy Perrin said:

This thread was for the Nemo. The Alonefire stuff should go in the Alonefire thread. I didn’t catch that you had an Alonefire when I left the comment above. I’m not sure if Ulf has also tested the Alonefire spectrum.

 

Why not put a UV blocker on your Alonefire and see if the “blue” disappears?

Because I do not have one yet and was asking before I buy one in order to look for a suitable one.

 

And yes the alonefire sv13 is 26650 and the body is identical to the one posted and it looks the same complete with fluorescent ring and 40.9mm glass filter measurements. "Nemo" just means no name I'm sure there are several general rebrands of the same thing from different sellers/importers.  

[Andy Perrin]

35 minutes ago, xonefs said:

"Nemo" just means no name I'm sure there are several general rebrands of the same thing from different sellers/importers.  

Indeed — that was my own joke! But we did mean a particular unnamed torch at the time. It may have rebrands, yes, the question is whether any blue leaks, I thought. If it is the exact same one as the original Nemo, the answer is no. If it is more like the larger Alonefire version I’m not sure. 
 

Either way, though, blue fluorescence from 365nm torches is very common. I usually tweak the white balance to reduce it. Easy test is to put the UV blocker on the torch and see if the apparent “blue leak” vanishes. If it does, it was really fluorescence.
 

Apologies for my confusion, I need to slow down and read carefully. 

[KhanhDam]

ok i found several varieties uv flash light on line. I have copied price and description below incase anyone in the future needs to buy one as links often go dead. on aliexpress.com first one uses 4 leds, the rest use 3 leds. 2nd one uses 26650 battery . 3rd and 4th one use four 18650 batteries side by side making them short and stocky.  last one from topcon store, seems like the best deal, so I"m gonna get that one. 

[ulf]

18 minutes ago, KhanhDam said:

 on aliexpress.com first one uses 4 leds, the rest use 3 leds. 2nd one uses 26650 battery . 3rd and 4th one use four 18650 batteries side by side making them short and stocky.  last one from topcon store, seems like the best deal, so I"m gonna get that one. 

Actually the two last ones use three LED arrays each with four LEDs in parallel. Each rated to something like 10-12W.

The "Nemo" type have one LED array of similar type.

The Convoy S2 has a single UV-LED rated to around 3W.

 

These ratings are for the electrical input power. What we really are interested in are the optical output power and the beam-shape.

In the LED conversion from electrical to optical power most power is lost as heat that has to be cooled away. Normally the efficiency is around 30-35% in these types of LEDs.

Then the filter reduces the output with 30-35%. as the LED-peak and the filter peak are not the same

 

• The "Nemo" is advertised as a 15W torch and is powered with ca 8W from the battery. That would give almost 2W optical power.
• The stubby Alonefire advertised as a 45W and a 42W torch in different adds seam to be supplied with ca 28W in the beginning, when turned on with fresh batteries and then less and less during fading. That would give maybe 6-7W optical power after the filter. That still is really impressive, but you should be aware of that the output power is not stable and most intensive in the beginning!

 

 

[KhanhDam]

thanks, that was a very good explanation. I wonder if a simple ice pack around the torch would help keep the output light high. I just ordered some so I should know soon. 

[ulf]

35 minutes ago, KhanhDam said:

thanks, that was a very good explanation. I wonder if a simple ice pack around the torch would help keep the output light high. I just ordered some so I should know soon. 

No it will not. There are several combined thermal design flaws adding up to the fading with different components that are not well thermally coupled to the case.

It is not just the LEDs that are not good enough cooled.

---

The intensity of a LED is mainly dependent on the current flowing through it.

 

The "Nemo" has constant current ICs regulating that as long as the battery voltage is high enough. After that the intensity is slowly fading as the battery voltage is going down. That happens before the battery is fully discharged when the voltage under load goes below 3.8V

 

The "Alonfire H42" do not have any active constant current control, just different serial resistance "components" in the supply path that limits the LED Current.

Several of those are current and temperature dependent and interacts wildly when they heat up due to the current flow.

Most components can be viewed as combinations of ideal components for simulation. 

 

All resistances in the path work together and makes things very difficult to simulate exactly as each of them get their own heat-up depending on the thermal cooling structure. 

These are some of the "resistances" in the path, most of them that are not stable:

• The LEDs dynamic resistance. (Increases with temperature)
• The serial resistance in the MOS-FETS that are used for ON/OFF-control  (Increases with temperature and lower control voltage)
• The copper conductors on the circuit boards and in cables.  (Increases with temperature)
• A few resistor components on the control board. (comparably stable)
• The serial resistance in the LiPO batteries.  (changes with load and charge state)

[Andy Perrin]

Diodes (including LEDs) have current that depends on voltage in an approximately exponential way, so small changes in voltage applied to the LED give big changes in current, and the light output is proportional to current. The temperature-dependent resistances that Ulf names above each affect the voltage across the LED, leading to even small temperature changes being “amplified” in the LED’s output. 
 

It is amazing to me that they didn’t put a DC-DC converter device in there to stabilize the AloneFire, but anything to save a buck!

[moondigger]

Does anybody know where I can get one of these Nemo lights in Dec 2023? I mean the one Ulf describes with constant current ICs to help keep output levels steady. I was leaning toward getting a Convoy S2+ or S21- model, as I don't have any 26650 batteries, but do have 18650s and 21700s. But the higher output of the Nemo has me reconsidering.

[colinbm]

@moondigger There is a new light on the market, it is by an Australian seller & has an Irradiance output of 36mW/cm2.
The so called Nemo has 12mW/cm2.
https://fluoromins.com.au/opal-hunters-365nm-torch/fluoromins-f8-365nm-torch/

Here are my tests.....
36mW/cm2 at 380mm distance, which is the industry standard distance for UV LEDs.

The bright spot is 63mm at a distance of 380mm.

[Andy Perrin]

I mean, doesn't it also depend on what lens is on the end and how big the spot is? You can increase the irradiance just by focusing the dot smaller...

[colinbm]

The spot is not much smaller then the supposed named Nemo which is has 4 emitters & a softer circle.

[Andy Perrin]

1 hour ago, colinbm said:

the supposed named Nemo

You don't like my punny nickname for it? Nemo is just Latin for "no name" (which was the situation when we first found it).

 

It does look to me like the Nemo (or whatever it's real name was) spreads the light a bunch more. Keep in mind that if you double the spot diameter with all else the same, the irradiance will go down by a factor of 4 (since it depends on the area). So it's rather sensitive to the diameter. This is why we really need one of those integrating spheres to collect all the light.

[ulf]

1 hour ago, Andy Perrin said:

Keep in mind that if you double the spot diameter with all else the same, the irradiance will go down by a factor of 4 (since it depends on the area). So it's rather sensitive to the diameter. This is why we really need one of those integrating spheres to collect all the light.

That is what I use when comparing intensities between flashlights properly. I created one when we discussed the "45w" torch that gradually dimmed when heating up.

The sphere is internally coated with a special diffuse coating of barium sulphate.

[colinbm]

In the face of no International Standards for UV LEDs the NDT people have this one with the UV LED manufactures use, & that is, mW/cm2 at a distance of 380mm from the emitter to the entrance pupil of the Irradiance Meter, which I have used above, & in this case the filter is in place.

[colinbm]

Also Total Irradiance is not so useful when you are using the bright area for your photography, but the size of the spot with its irradiance in mW/cm2, is a useful guide.

[colinbm]

@ulf  By-the-way how do you get all the light into the Integrating Sphere with the filter we use in place ?

[ulf]

31 minutes ago, colinbm said:

@ulf  By-the-way how do you get all the light into the Integrating Sphere with the filter we use in place ?

The opening and sphere are big enough to handle the beam from the "45W" flashlight. Integrating spheres can be of ant size from the tiny one your spectrophotometer have to really big walk in spheres.