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Convoy S2+ UV

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#1 Cadmium

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Posted 14 November 2017 - 02:55

I only wanted to point out for everyone that not all of the "Convoy S2+" torches are for UV.
Most of you may be well aware of this fact, but to those who go looking for one of these torches, beware that there are different versions, and only one of them has a Nichia 365nm LED in it.
Here is a link showing some different versions, so don't accidentally order the wrong one. Make sure you get the "Convoy S2+" that has the "Nichia 365nm" LED in it.
Indeed, I highly recommend the Convoy S2+ Nichia 365 version, it is only about $20 and works extremely well. Of course, the MTE 301 and 303 torches work extremely well also, albeit more expensive.
https://www.gearbest...onvoy-s2-_gear/

Related: If you are getting some other UV torch, make sure your LED is 365nmm and not 400nm (or the like), especially if you want to use a U-340 filter on the front,
because U-340 is designed to remove any light above 400nm (violet/blue light, etc.).
As some of you may know, if a torch is advertised to have a 365nm LED, this isn't always accurate, the nm may actually be higher.
I know that the MTE 301/303 torches and the Convoy S2+ (Nichia 365nm version) definitely all have the Nichia 365nm LED and work best for fluorescence photography (UVIVF).
I can't speak as highly about any other torches, those are the only two I have used that work extremely well for 365nm/fluorescence photography.
It is possible to induce green fluorescence with violet/blue light, but a U-340 will prevent that from happening.
Use 365nm light. Otherwise, remove the U-340 filter.

Edited by Cadmium, 14 November 2017 - 03:11.


#2 Andrea B.

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Posted 14 November 2017 - 21:10

A 400nm peak torch is NOT a good UV torch. It is basically a Violet torch. I have a 400nm UV-Led and can support the previous discussion. You do NOT use a 340nm peak filter over a 400nm peak Led and expect to have it work.
Srsly any people using 400nm torches for UV -->> just NO.
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#3 Andy Perrin

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Posted 14 November 2017 - 21:15

I have heard that if you are looking for bodily fluid fluorescence, that band works better than 365nm, but that's not what most of us are after!

#4 Cadmium

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Posted 15 November 2017 - 03:13

I have all three, MTE 301, MTE 303, and Convoy S2+ (365nm Nichia version). I have replaced the clear front glass of all those torches with U-340 2mm thick,
and there is no difference in fluorescence brightness with or without the U-340.
U-340 and UG11 are the best glass to use for removing visual violet/blue light from 365nm UV light (or 'black light'), U-340 is half the price of UG11.
Some people often ask, "why use U-340 with the 340nm peak, why not use U-360 or UG1 which have 360nm peaks?".
The reason we use U-340 is because it cuts off the blue, it doesn't transmit above 400nm at 2mm thick, whereas U-360 and UG1 tend to leak a bit of violet/blue visible light above 400nm.
When you look at the overlapping graphs of each glass type, you see that the U-340 transmits 365nm, but has no visible violet/blue that reaches the target, only invisible UV.
Thus there is no visible reflected violet/blue light mixed in with actual fluorescing visible light, so only UV Induced Visible Fluorescence (UVIVF).
If you use an unfiltered common Black Light you see and have violet/blue light mixed in with the UVIVF, no pure fluorescence.
Here is a graph of that:
Attached Image: U340_1mm_2mm_U360_2mm_UG1_2mm.jpg

PS: Pertaining to the term 'woods glass', that is an old term and old glass, no longer made. It filtered out 'most' visible light (not all).
The closest modern filter glass to the old 'woods glass' is U-360 which you don't want to use, as noted.
Also, some UV lights are filtered with Hoya U-325C which is almost identical to Hoya U-330 (Schott UG5), and it passes much more violet/blue/green visible light than even the U-360/UG1 glass.
So use 365nm UV and stick with U-340 2mm for filtering out visible.

I recommend this link for UVIVF info also:
http://photoextremis...graphy-tutorial

Edited by Cadmium, 15 November 2017 - 04:51.


#5 Mark

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Posted 16 November 2017 - 01:02

I also have both an MTE303 and an S2+, and find both to be great UV torches (compared to a number of other UV LED lamps/flashlights I've tried). Only note from my observations is that the MTEs are 'cleaner' - by which I mean they appear to have less purple/violet spill over than the S2+ (both by [brief & reflected] naked eye observations, and in head to head photo tests). Although, the S2+ does shine with a little less of a hot spot (which makes for easier illumination / light painting of larger subjects). In the end they are quite comparable, notwithstanding for the cost difference of course.

As for capturing 'pure' fluorescence, that is something I'm still struggling with, as even these great torches emit a fair amount of visible light. That is, 'fair', insomuch as it contributes to VIS contamination in an extended duration exposure - which, in turn, is not at all uncommon for shooting subjects with faint / subtle fluorescence. Add to that secondary illumination from any of the fluorescence itself, AND off target fluorescence (lint!!), and it becomes rather difficult to capture 'pure' fluorescence (of the target). But regarding the overall point, I admit, its much closer to 'pure' with these torches than with some cheapo UV torches which actually use 400 nm LEDs and any other such sources with significant and obvious VIS bleed over/around 400 nm. And another benefit - common to LED sources in general (over, for example, fluorescent bulbs) is the near complete absence of IR; which is useful for shooting, for example, UV induced IR fluorescence.

#6 Cadmium

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Posted 16 November 2017 - 04:13

Andy, Yes, I know people who have used violet/blue ~400nm to do fluorescence. I have never tried it, I don't have any 400nm lights.
But I think what is happening with that, is the violet/blue 400nm is exciting some kind of green fluorescence, not sure, but using a U-340 for that would defeat the process, and nothing would fluoresce.
Which brings me to Mark...

Mark, That was the reason I posted this, because someone was using the U-340 filter, and it was not fluorescing anything, but it was fluorescing without the filter,
so my guess is that they have a 400nm light.

Honestly, I don't think I would get another MTE, not now, because the S2+ 365nm is so inexpensive, and has the more even light with no hot spot.
I have not noticed the color difference, but I have the U-340 on all of them, so I will look for that with no filter.
It would be nice if Convoy made a bigger brighter 365nm version, but I find that the S2+ would be my pick of the those mentioned.

Edited by Cadmium, 16 November 2017 - 04:17.


#7 Andy Perrin

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Posted 16 November 2017 - 04:20

Cadmium, there still seems to be quite a bit of stuff labeled "Wood's glass" available online? I bought some from a theater supply house a bunch of years ago (2012ish). I take it that what was sold was not the ORIGINAL Wood's glass.
--
And yes, I'm sure to use a 400nm torch, you'd need a different filter to block the torch.

Edited by Andy Perrin, 16 November 2017 - 04:23.


#8 Andrea B.

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Posted 16 November 2017 - 05:28

Hot spots in torches can be dealt with using some kind of diffusing filter. But for a UV torch you would have to find diffusing glass which properly passed the UV. And some diffusers do cut down a bit on the total transmission. Dr. Klaus once included a nifty, thin plastic diffuser with one of his torches. The plastic looked slightly "frosted". Worked very well.

Alternate work-around is to move the torch (and thus the hotspot) around during the photograph as in 'painting with light'. This of course requires a slightly longer exposure to properly diffuse.


As for capturing 'pure' fluorescence, that is something I'm still struggling with, as even these great torches emit a fair amount of visible light.

We handicap ourselves a bit by practicing such wide-band fluorescence in both the illumination and the capture. :rolleyes: Narrow-band excitation filters and emission filters would help. But then we wouldn't get the nice variety of different different colours that we sometimes see.

Nothing is ever easy, it seems. :P But I've often suggested that we shouldn't let perfection get in the way of pretty darned good. Not that I'm able to always avoid feeling that little perfection pitchfork myself.
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#9 Mark

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Posted 16 November 2017 - 21:46

Regarding the option of using a diffuser to tame the hot spot in these torches: I tried this (link), even with a quartz diffuser the high degree of drop-off in UV intensity makes this option much less tenable. I think this goes to show that the apparent remarkable power of these torches is in large part due to the fact that they illuminate such a small area. I have since opted to use the light painting approach instead whenever necessary.

Also, it wasn't going to be easy to cut that square quartz diffuser down to a circle which would snugly fit into my MTE torch ;)

#10 OlDoinyo

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Posted 17 November 2017 - 02:52

I have always understood the phrase "Wood's glass" to apply to a whole class of glasses and filters, including the U- and UG- series filters and similar products. I believe they all have passbands in the same general ranges and with similar profiles, and presumably they are made with similar active ingredients. The differences between them seem to be due to varying thickness and concentration of the active principle, although variations in substrate composition can also play a role.

#11 Cadmium

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Posted 17 November 2017 - 04:17

Yes, I agree, but I encounter some people arguing that none of the glasses you listed are actual 'woods glass'. They are looking for woods glass. :-)
https://en.wikipedia.../Wood%27s_glass

My main point being that U-340 and UG11 are the best U glass to use for 365nm to cut violet/blue.

Edited by Cadmium, 17 November 2017 - 04:20.


#12 Cadmium

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Posted 19 November 2017 - 04:17

By the way, pics of the Convoy S2+ and MTE 303 with Hoya U-340 2mm thick filters installed.
Attached Image: UV_Torch_Labels_2_1080.jpg

Attached Image: UV_Torch_Labels_3b_1080.jpg

Also, Convoy S2+ filter replacement illustration guide.
Attached Image: U340_Convoy_S2_Instruct_1080.jpg