DIY UVA, How do you make your UVA ?

[colinbm]

DIY UVA, How do you make your UVA ?

 

Carbon Arc......

 

[Andy Perrin]

For UVA, sunshine is enough for me, or a Convoy. Carbon arcs will make UVA, and B, and C...not nice, very hot!

[Stefano]

I tried carbon arcs before. Just take the graphite rod out of a pencil, and connect it to a power supply, 32 V, 5 A. They are BRIGHT. I melted my alligator clips twice doing that, and I don't want to destroy other pencils. I was wearing my polycarbonate goggles, to at least cut UV. I even photographed the UV spectrum with a diffracton grating.

 

 

It seems to match this: https://www.google.c...QMygwegUIARDmAQ

 

And yes, maybe I should have worn a welder mask.

 

I also tried, out of curiosity, to make a halogen blacklight. Took a 50 W halogen bulb, the type with the reflector, and put my 2 mm ZWB2 and my 2 mm chinese BG39 filters on it. Having a diameter of 50 mm, they perfectly covered the bulb. I also ran the bulb at 18-20 V instead of 12 V. I knew the filters would have heated up, it was just an experiment. It did produce some UV, paper glowed blue, highlighters glowed too, and I could charge glow-in-the-dark paint. But after a minute the filters were too hot to touch. It maybe produced 50-100 mW of UV, comparing it to my 50-60 mW 340 nm LED.

[colinbm]

Stefano here is a halogen 20w..........useless....

 

[Stefano]

Yes, not an efficient way to produce UV. As I said, it was just an experiment, if you want to produce UV efficiently use an LED or a mercury-based source, such as fluorescent or mercury vapour.

 

Halogen lamps can produce even UVB, very little but they do. Usually they are filtered to block UV. I have used incandescent light sources for UV photography. Dark polycarbonate goggles and dark sunscreen, so they work.

[colinbm]

Yes the trouble is finding ones that have real quartz glass.

[ulf]

Many (all?) of these special lamps have real quartz glass and transmit UV, a bit beyond 350nm.

Not much, but at least a bit.

GPS01_1028526_Low-voltage_halogen_lamps_without_reflector.pdf

They are special lamps for technical applications and projectors.

They are getting really hot and are designed for fan cooling.

 

According to the spectrometer specialist that suggested these lamps, the output is quite close to a blackbody radiator with matching colour temperature.

 

The 20W lamp has a colour temperature of 3350K.

A theoretical 3350K-source has this spectra:

 

The theoretical blackbody spectrum for 2616K as measured by Col above looks like this:

I tried to match the diagram shape and range with Col's and they look rather similar between 450nm and 750nm.

[Andy Perrin]

I tried carbon arcs before. Just take the graphite rod out of a pencil, and connect it to a power supply, 32 V, 5 A. They are BRIGHT. I melted my alligator clips twice doing that, and I don't want to destroy other pencils. I was wearing

 

Having done that a few times in my youth, if you put enough power through a piece of pencil lead, it WILL explode and make hot shards of pencil lead fly everywhere. (This will happen with any pencil lead but particularly thin pieces like for a mechanical pencil are prone to it.) Anyway, don't recommend that anyone else try this without safety glasses and making sure the local environment isn't flammable.

[Stefano]

Having done that a few times in my youth, if you put enough power through a piece of pencil lead, it WILL explode and make hot shards of pencil lead fly everywhere. (This will happen with any pencil lead but particularly thin pieces like for a mechanical pencil are prone to it.) Anyway, don't recommend that anyone else try this without safety glasses and making sure the local environment isn't flammable.

Agree. I have done a lot of dumb things, I admit, but if you want to try it be careful.

[colinbm]

Many (all?) of these special lamps have real quartz glass and transmit UV, a bit beyond 350nm.

Not much, but at least a bit.

GPS01_1028526_Low-voltage_halogen_lamps_without_reflector.pdf

They are special lamps for technical applications and projectors.

They are getting really hot and are designed for fan cooling.

 

According to the spectrometer specialist that suggested these lamps, the output is quite close to a blackbody radiator with matching colour temperature.

 

The 20W lamp has a colour temperature of 3350K.

A theoretical 3350K-source has this spectra:

 

The theoretical blackbody spectrum for 2616K as measured by Col above looks like this:

I tried to match the diagram shape and range with Col's and they look rather similar between 450nm and 750nm.

 

Thanks Ulf

I did try an older Sylvania Quartz Tungsten Halogen 21v 150w without much UVA.....

 

 

[dabateman]

I just fixed my bad convoy, with broken 365nm led, with a 16mm 385nm LG LED from ebay. Got 5 pack for $7.

It fit and works well, just unsoldered the old Led plate and solder in this disc. Seems to handle the old 2 x7135 drivers well.

 

The spectral peak is 388nm, ranging from 370nm to 400nm. Looks like a good complementary flashlight/torch for my good convoy with similar light output.

 

Thats how I have wanted to DIY UVA for a while now.

[colinbm]

I would like a LED flashlight/torch that covered 300-400nm.

[Stefano]

I would like a LED flashlight/torch that covered 300-400nm.

How is your four wavelengths LED project going? This one: https://www.ultravioletphotography.com/content/index.php/topic/3769-the-future-has-arrived

 

I have a 340 nm LED, Thorlabs sells 325 nm and 300 nm LEDs. They are all weak. I think that at the moment there isn't a way to have a uniform UV spectrum with LEDs, I saw a "UV full spectrum" LED which uses phosphors, like a normal white LED, but the spectrum is bumpy.

[Stefano]

I just fixed my bad convoy, with broken 365nm led, with a 16mm 385nm LG LED from ebay. Got 5 pack for $7.

It fit and works well, just unsoldered the old Led plate and solder in this disc. Seems to handle the old 2 x7135 drivers well.

 

The spectral peak is 388nm, ranging from 370nm to 400nm. Looks like a good complementary flashlight/torch for my good convoy with similar light output.

 

Thats how I have wanted to DIY UVA for a while now.

Did you use an LED with roughly the same forward current? If so it is ok to swap it.

 

And do you still use the 2 mm U-340 filter (I think you have it)? Because it would cut down quite a bit at 388 nm.

[colinbm]

Thanks Stefano, yes I have the four wavelengths LED project going? This one: https://www.ultravio...ure-has-arrived

It is OK but not low enough for me & it needs filtering to cut the 395 fluorescence.

I am waiting on a dual LED, 6 x 375nm & 6 x 365nm, intermixed. maybe a week or two.

[enricosavazzi]

If the purpose is UVA still-imaging with an illumination spectrum broader than a 365 nm LED, why not a non-coated xenon flash tube? It seems the simplest and probably cheapest way for a relatively high intensity. Many of our members use UV-enhanced electronic flash. I notice this has not been mentioned yet, so perhaps this thread assumes that a continuous UV emission is required? Or perhaps a modified studio strobe does not qualify as DIY?

 

If a continuous (in terms of human visual perception) emission is required, pulsed power supplies can flash a xenon tube tens of times a second (at a lower intensity of course).

 

If the source must provide a truly constant emission w.r.t. time, things become more complex, but there are continuous-arc xenon tubes for e.g. microscopy.

 

If a simple, non-technological DIY method is the goal, the static discharge produced by unwinding scotch tape in air does produce UV, although probably not much. If you unwind scotch tape in a vacuum the emission becomes mostly X-rays, probably strong enough for DIY radiography. Changing the composition and pressure of the atmosphere has not been tested afaik, but might be a way to tune the emission spectrum.

[colinbm]

Hi Enrico

I have the Godox flash unit, but I haven't found out how to use it with my Sigma Quattro camera & Lumix G3 cameras.

My past photography teacher was going to help me, but them came along this virus & he hasn't got back to me, so I have kept looking for some holy grail of UVA illumination.

[JMC]

What do I use for UVA?

 

Sunlight where ever possible.

 

Hamamatsu 200W continuous source, either xenon or mercury xenon. This gives a small aperture output, so is easy to filter if needed. It is however extremely powerful and potentially dangerous. I recently picked up a fiber splitter for this which gives me 4 smaller diameter fibers from it, which I think will be useful for macro imaging and microscopy.

 

BlakRay 365nm fluorescence tubes. 2x8w 12" tubes, and a pretty good output. Also have 302nm tubes if needed, and 255nm tubes are also available.

 

Bowens 600w flashes. I've got uncoated glass and some custom made quartz tubes for these. For UVA though uncoated glass is fine.

 

Speedlights. Some Canon and Nikon flashes converted for UV induced fluorescence.

 

Some mercury xenon lamps for my microscope (100w and 50w) which I suppose could be used for normal photography, a bit like the Hamamatsu.

 

I've played with LED but not much, and I don't have any Convoys or similar.

[enricosavazzi]

Hi Enrico

I have the Godox flash unit, but I haven't found out how to use it with my Sigma Quattro camera & Lumix G3 cameras.

My past photography teacher was going to help me, but them came along this virus & he hasn't got back to me, so I have kept looking for some holy grail of UVA illumination.

I don't have the G3 anymore, but any camera that has a hot shoe and/or supports flash sync in manual mode should work with the Godox units set to M. I only have the AD200 (two of them actually), but other models should work in the same way, either directly mounted on the hot shoe, or with a flash sync cable between camera and strobe, or with a Godox wireless master on the camera's hot shoe (depending on which Godox flash you have).

 

I don't remember whether Panasonic Micro 4/3 cameras are compatible with the Olympus flash system. If they are, then a Godox X1-T O or XPro O (or the newer version of the X1T-O, which might have a different name) should work. I don't know if Godox makes a wireless master for your Sigma Quattro.

[ulf]

Good point Enrico,

 

I have two AD200 and they are the most used light-sources for my UV-photography.

I always use them in Manual mode as that works best for my setup, switching filters all the time.

I get more consistent exposure that way and have learned the approximate setting for each filter-stack.

 

The sync connector o the AD200 is a standard 3.5mm socket that should work with any camera with a sync-connector or an adapter fitted to the flash shoe, by connecting them with a sync-cable.

 

In my setup I can use the dedicated wireless flash remote on my Sony camera for setting both the flash's power at the same time.

 

Without that option you can set the power individually on each flash for a cable-based setup.

Old flashes had high voltage at the trigger input, but that was long ago.

The modern Godox flashes will not harm your camera.

[Stefano]

Is it possible to run flash tubes continuously (at a much lower power) using some sort of ballast?

[enricosavazzi]

Is it possible to run flash tubes continuously (at a much lower power) using some sort of ballast?

Probably not continuously, since they are designed for use within a range of discharge currents and voltages and have an impedance supposed to match large capacitors, but it is possible to fire them in rapid sequences of up to a few seconds (because of heating constraints). Quite a few speedlights actually have this function built-in, as a stroboscopic sequence or as an approximation of rear-curtain sync.

[dabateman]

Did you use an LED with roughly the same forward current? If so it is ok to swap it.

 

And do you still use the 2 mm U-340 filter (I think you have it)? Because it would cut down quite a bit at 388 nm.

 

Yes. Currently on that light I just have the cut Lee 750 frost filter. No other. The Led is quite tight at 370nm to 400nm. So may not need filtration. But I might stick a ZWB2 filter inside for fun. I have a couple at 1.5mm thickness each.

I have 2 of Cadmium's 20.5mm U340 2mm filters. But I don't use them in Convoys anymore. I use them to cut IR from deep UV filters, like my 303bp10 filter.

 

Thd convoys have 2mm ZWB1 filters currently. I now have 3 at 365nm and one I modified to 385nm with the LG 3535 led, rated as 5W. But I only have 2 drivers in that light. I could go up to 5.

 

Some flashes have a pulse mode. So almost looks continuous. But in order nearly visible. So do leds, but much higher frequency, so looks continuous to our eyes. You can wave your hand under a cheap led and see near stop motion, if timing is slow.

I play around with many different light sources to find the best for me.

 

[colinbm]

Thanks Enrico & Ulf

I have a Godox AD200 & I think I will be happy with it attached via cable to the hot shoe mount, it being simplest & I can expand later.