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UltravioletPhotography

Convoy S2+ UV


Cadmium

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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.

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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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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!
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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:

post-87-0-15843700-1510713863.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://photoextremist.com/ultraviolet-induced-visible-fluorescence-photography-tutorial

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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.

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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.

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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.

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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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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 ;)

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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.
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  • 4 weeks later...
I just ordered a Convoy S2+ for Christmass! I am just wondering, is there any problem if I use my Baader-U instead of a U340 filter in front of the torch?
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Baader should work fine I think. Just have to find a way to attach it, which is a nice thing about the MTE torches, they have front threads, so you can use a step-up ring for mounting filters on the front, the Convoy has no front threads.
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Yeah I wanted to get a MTE but too expensive and I have a hard to find any on the net :(

I will build a small contraption to make the Baader-U stick the Convoy. Now I need to find some nice UV-protection goggles.

 

Thanks Cadmium!

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I have purchased my MTE 301 and 303's here (below link), was the best price I could find for my currency.

https://www.urbanout...l-flashlight-36

 

Other than their low cost, the thing I really like about the Convoy S2+ is they have a more uniform beam.

 

Here are the goggles I use:

http://www.ultravioletphotography.com/content/index.php/topic/2145-uvex-ultrasonic-9302045-goggles/page__hl__uvex__fromsearch__1

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Cadmium, thank you so much for your help. Those goggle are awesome, I just ordered a pair.

I also ordered the Baader UV/IR cut filter, that way I will be able to do some UVIVF a last! I have many fluorescent minerals to experiment on :)

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You're welcome. You will like the Convoy S2+, and the Goggles too.

I just ordered 3 more of the Convoy S2+ because I sent mine to Andrea with U-340 filters installed. I really like them a lot more than the MTE.

http://www.ultravioletphotography.com/content/index.php/topic/2462-uv-induced-infrared-fluorescence-investigation/page__view__findpost__p__18114

 

NOTE: Don't weld in the goggles, anyone, they say they can be used for welding on some sites that sell them, but that is certainly a bad idea for electric welding,

you need full face covering for that, and I really doubt the shade is strong enough.

You may be able to use it for acetylene welding, but even so those goggles are not industrial, get the real thing for any kind of welding.

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Yeah I already read all the threads mentioning the Convoy S2+, what a wonderful little lamp!

But now the real (idiot) question: can we use electric welding as a light source for reflected UV photography? :P

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Who is being silly?

Yes, arc welding. I said electric welding, as apposed to gas (oxygen/acetylene).

Yes, you could use arc welding light, but quite inconvenient, there are probably lamps that would work the same, and since it is so bright, I don't know what the IR would be like compared to sunlight.

You could certainly photograph arc welders welding... as long as you are well protected, full welding gear, face shield (solid shield with rectangular #14 welding filter) and clothing.

Recommended filters for various types of welding:

https://www.osha.gov...ing-welding.pdf

You can also use #14 for the sun.

Arc welding can quickly give you a blistering sunburn if you are not protected, which could certainly cause more serious problems in the future.

You should never watch anyone weld, even from a distance, unless you have protection.

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Cadmium, I was speaking to Hornblende (or are you saying I'm the one being silly? I won't rule it out...). But an arc lamp is the same process, as far as the light production is concerned, so yes, we have those and they are a good source of UV. Especially the xenon ones.
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  • 2 weeks later...

I got my Convoy! Damn this thing is powerfull, the fluorescence of paper and clothes is visible from 10 meters away.

I have not received my UV-goggles yet, in the meantime I am using my ski goggles which blocks UV pretty well (I don't see any paper fluorescence when I use them as a filter in front of the Convoy).

I will start experimenting with UVIVF soon :)

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