Best UV Light Source (LED vs Fluro vs HID etc)

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timparkin

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Yes, the question is how much of the 500W is gong to end up as UV vs visible light ? My array ended up being around 200 watts and works well... For an 11x14 print area it gives me 6min exposures for the Na2 Pt/Pd process. One big advantage of using the LED strips is you can make it as big or small as required - If I had my time again I'd build a bigger box, but that's because I've moved house and have a bigger darkroom now.

Thanks James!

I think mine should be similar to yours - I've got the 5m 3528 600 LEDs strip. I'm building an 18"x14" array which is using 4 5m strips. Does your unit get very warm in use? I'm mounting them to an aluminum sheet but I also have an A4 size heatsink that I can use on top.

As far as the 500W unit goes, it's an array with the same LED properties as our strips so it should be similar. They currently sell fixed units with these 500W arrays inside them (and also do 1000W units with twof of them in. But the arrays are only for visible LEDs at the moment. I'm talking to them about putting the UV version in. (they also do multi unit housings with power supplies and heatsinks etc).

I'm just going with the strip LED version now but it will be interesting finding out what else is available.



Tim
 

Vaughn

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Faster printing times are not necessarily better -- and longer exposures may produce better images.

Just something to think about when designing your light system.

More here for discussion: (there was a url link here which no longer exists)
 

timparkin

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Faster printing times are not necessarily better -- and longer exposures may produce better images.

Just something to think about when designing your light system.

More here for discussion: (there was a url link here which no longer exists)

Just replied to that forum. I personally don't see how it can make a difference but I'd be interested in trying (as mentioned - by masking a frame and making half LED and half slow flourescent).

Tim
 

calebarchie

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Elaborate?

James touched on this one with his post. A lower wattage array can have a greater output given it is cooled properly, more efficient and have less waste heat energy. Using 500W is a bit redundant if you use poor heat management, may appear good on paper but how do you know its true output?
 

michaelorr

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James touched on this one with his post. A lower wattage array can have a greater output given it is cooled properly, more efficient and have less waste heat energy. Using 500W is a bit redundant if you use poor heat management, may appear good on paper but how do you know its true output?

It could be this is NOT the best interpretation. The LED lumens output should be what it was designed to be, at the current drain it was meant to operate at. Potentially one could operate the LED at a lower current, and the heat would be dissipated in the resistance used to lower the current drain. Or one could operate the LED at a higher current (more watts to the diode), so more light output is achieved but more heat is dissipated in the LED, and must be extracted. The need to sink the heat is to get it out of the diode so that the diode junction doesn't get destroyed from thermal runaway. The point is that for all intents and purposes the rated power of the diode in the form of heat needs to be removed from the device to the heat sink, regardless. The point is not meant to be the more heat sink is applied the greater the output of the LED can be achieved. Stick to the design parameters of the LED and make sure that the heat sink is adequate to remove the heat specified, 500 watts of heat (which is a lot of heat) in order to operate without destroying the LED. 500 watts is nearly 5 amps at 120v.
 

timparkin

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Michael, more than one way to skin a cat. But yes, as a rule of thumb, proper heat management is crucial. In terms of lux output, energy efficiency, stability and diode life.

Michael is quite correct (I've a PhD in Electrical Engineering - it's not in LEDs, it's actually in assessing rotor bar failures in oil rig drill head pump motors via time domain finite element modelling of motor electromagnetics and nodal analysis of driver circuits but I've learned a little about general electronics along the way).

Fortunately you can just buy an off the shelf 500W heatsink - see http://www.satisled.com/images/v/201211/a/13526016112.jpg

There is very little complicated about LEDs beyond getting the right voltage and dumping the heat.

Tim
 

timparkin

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Me and Michael are saying the same thing? You don't need a PhD for this, maybe for interpretation on the interwebs though.

Apologies I misunderstood your statement "A lower wattage array can have a greater output given it is cooled properly,"

Tim

p.s. Still waiting for the elaboration on "If only it were that easy"
 

calebarchie

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Apologies I misunderstood your statement "A lower wattage array can have a greater output given it is cooled properly,"


p.s. Still waiting for the elaboration on "If only it were that easy"

I am simply using laymens terms (which of course are going to open to nuanced interpretation). What is the point of speaking in engineer gibberish on a photo forum? (or "wankineer" I like to call it).
I doubt the first CPU cooler you linked would of been sufficient, at least I am not aware of any ~500W consumer CPUs.

As for the second one might be more suitable however it comes from the same place as these shonky LEDs anyway.
 

michaelorr

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I did take a rather circuitous route to say "take care and mind the specifications." The LED lumens output is what it is. The LED needs to be run at specifications. Practically all the power taken up by the LED array is expended in heat, not light. All that heat needs to be removed from the LEDs. 500W of power needs 500W of heat sinking. Mine was not meant to correct anyone, just as a caution so as to not destroy inadvertently the LED strips.
 

Bob Carnie

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Has anyone here tried this unit or have an opinion ??- I currently own a Nurac Metal Halide unit and want to go larger and am waiting for any reviews on this unit before purchase.
My area of interest is exposure for negatives to produce Pt Pd prints and Tri Colour Gum over Palladium


sorry for the copy and paste that follows but this is right off their website.


STARLIGHT UV LED Screen Exposure System
Starlight is NuArc’s versatile and affordable tabletop or stand-mounted UV LED screen exposure unit. It’s ideal for conventional exposures, and an optional CTS retrofit kit turns Starlight into a computer-to-screen (CTS) UV LED screen exposure system. Starlight's UV LEDs save energy costs, reduce screen exposure time, speed up production, and operate at far lower temperatures than metal-halide lamps. And, unlike expensive metal-halide bulbs that require replacement every year or two, Starlight's UV LED light source can last for decades. In fact, M&R is so confident in the longevity of Starlight's screen-exposure LEDs that it backs them with a limited lifetime warranty against failure in normal use. And the high density of M&R’s screen-exposure LEDs (6840 on Starlight 3140 and 4320 on Starlight 2331) provides the finest detail, the most uniform coverage, and the quickest exposures available. M&R’s Starlights have more than three times as many LEDs per square inch as some competing products.

Starlight’s sophisticated digital touchscreen controller automates screen exposures. All the operator needs to do is select the appropriate exposure preset and press START. The entire process, including vacuum, exposure, and shutdown, takes place without further operator involvement. Starlight allows the operator to walk away after initiating the process because Starlight ensures that exposures will not begin until proper vacuum has been reached—and vacuum and exposure LEDs will shut off automatically upon completion of exposure. Vacuum and exposure times can be set between 0.1 and 999.9 seconds. And Starlight’s Job Recall™ speeds processing and increases productivity by enabling operators to save and recall up to 24 vacuum and exposure profiles—and identify each with a unique name or description.

Starlights quickly expose direct, capillary, and indirect emulsions. They work particularly fast on photopolymer emulsions, which can be exposed in as little as three to five seconds (results will vary based on emulsion type and thickness). Starlight UV LED screen exposure units can be located in areas housing unexposed screens because the ultraviolet light source and vacuum frame are enclosed, and the screen exposure lamp can't be turned on while the blanket frame is open. Starlights also incorporate several strips of yellow, non-exposing LED inspection lights for convenient setup. Starlights are available in two sizes: Starlight 2331 is capable of exposing screen frames up to 58 x 79 cm (23” x 31”) and Starlight 3140 is capable of exposing screen frames up to 79 x 102 cm (31" x 40"). Starlight 2331 is perfect for small and startup shops, while Starlight 3140 makes it easy for medium-size shops to quickly process larger screens and higher volume. If you're looking for blazingly And Starlight 3140 is compatible with most sizes of M&R’s Tri-Loc Registration System. fast quality exposures at an unbelievably affordable price, you'll find it all in the Starlight.

M&R is the world’s largest manufacturer of screen printing equipment, and the online M&R Store features a wide variety of genuine M&R OEM parts and screen printing supplies. The NuArc line includes UV LED exposure systems, CTS computer-to-screen imaging systems with built-in UV LED exposure capability, exposure units for CTS and conventionally generated screens, lithographic imaging systems, and freestanding vacuum frames. All equipment from The M&R Companies is built with M&R's unsurpassed attention to detail and commitment to quality, durability, innovation, and design excellence, and is backed by M&R’s unparalleled 24-hour access to service, support, and premium parts.
 

timparkin

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I am simply using laymens terms (which of course are going to open to nuanced interpretation). What is the point of speaking in engineer gibberish on a photo forum? (or "wankineer" I like to call it).
I doubt the first CPU cooler you linked would of been sufficient, at least I am not aware of any ~500W consumer CPUs.

As for the second one might be more suitable however it comes from the same place as these shonky LEDs anyway.

I didn't speak in wankineer - you said that a lower wattage array will give out more light if it is cooled better which in wankineer terms is incorrect. Unless you know more about LEDs than I do in which case please explain..

You're using lots of none-wankineer terms like "shonky leds" which have zero semantic content so I don't know what you're on about. Adding solid information to the thread would be really cool please.

Tim

p.s. Maximum single CPU wattage is about 300W (overclocked AMD FX) but cooling should keep CPUs down to 50 degrees (approx). LEDs can cope with more temperature, approx 80 degrees in some cases. So a CPU has to be kept at +25 over ambient and an LED at +55 over ambient. The CPU needs a lot more heat shunting. Hence I reckon a high powered water cooled heatsink should be enough.
 
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timparkin

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Has anyone here tried this unit or have an opinion ??- I currently own a Nurac Metal Halide unit and want to go larger and am waiting for any reviews on this unit before purchase.
My area of interest is exposure for negatives to produce Pt Pd prints and Tri Colour Gum over Palladium


sorry for the copy and paste that follows but this is right off their website.


STARLIGHT UV LED Screen Exposure System
Starlight is NuArc’s versatile and affordable tabletop or stand-mounted UV LED screen exposure unit. It’s ideal for conventional exposures, and an optional CTS retrofit kit turns Starlight into a computer-to-screen (CTS) UV LED screen exposure system. Starlight's UV LEDs save energy costs, reduce screen exposure time, speed up production, and operate at far lower temperatures than metal-halide lamps. And, unlike expensive metal-halide bulbs that require replacement every year or two, Starlight's UV LED light source can last for decades. In fact, M&R is so confident in the longevity of Starlight's screen-exposure LEDs that it backs them with a limited lifetime warranty against failure in normal use. And the high density of M&R’s screen-exposure LEDs (6840 on Starlight 3140 and 4320 on Starlight 2331) provides the finest detail, the most uniform coverage, and the quickest exposures available. M&R’s Starlights have more than three times as many LEDs per square inch as some competing products.

Starlight’s sophisticated digital touchscreen controller automates screen exposures. All the operator needs to do is select the appropriate exposure preset and press START. The entire process, including vacuum, exposure, and shutdown, takes place without further operator involvement. Starlight allows the operator to walk away after initiating the process because Starlight ensures that exposures will not begin until proper vacuum has been reached—and vacuum and exposure LEDs will shut off automatically upon completion of exposure. Vacuum and exposure times can be set between 0.1 and 999.9 seconds. And Starlight’s Job Recall™ speeds processing and increases productivity by enabling operators to save and recall up to 24 vacuum and exposure profiles—and identify each with a unique name or description.

Starlights quickly expose direct, capillary, and indirect emulsions. They work particularly fast on photopolymer emulsions, which can be exposed in as little as three to five seconds (results will vary based on emulsion type and thickness). Starlight UV LED screen exposure units can be located in areas housing unexposed screens because the ultraviolet light source and vacuum frame are enclosed, and the screen exposure lamp can't be turned on while the blanket frame is open. Starlights also incorporate several strips of yellow, non-exposing LED inspection lights for convenient setup. Starlights are available in two sizes: Starlight 2331 is capable of exposing screen frames up to 58 x 79 cm (23” x 31”) and Starlight 3140 is capable of exposing screen frames up to 79 x 102 cm (31" x 40"). Starlight 2331 is perfect for small and startup shops, while Starlight 3140 makes it easy for medium-size shops to quickly process larger screens and higher volume. If you're looking for blazingly And Starlight 3140 is compatible with most sizes of M&R’s Tri-Loc Registration System. fast quality exposures at an unbelievably affordable price, you'll find it all in the Starlight.

M&R is the world’s largest manufacturer of screen printing equipment, and the online M&R Store features a wide variety of genuine M&R OEM parts and screen printing supplies. The NuArc line includes UV LED exposure systems, CTS computer-to-screen imaging systems with built-in UV LED exposure capability, exposure units for CTS and conventionally generated screens, lithographic imaging systems, and freestanding vacuum frames. All equipment from The M&R Companies is built with M&R's unsurpassed attention to detail and commitment to quality, durability, innovation, and design excellence, and is backed by M&R’s unparalleled 24-hour access to service, support, and premium parts.

No experience but this is the unit that inspired me (including the inspection lights). If I get crafty I have a Rasberry PI waiting as an exposure controller.
 

calebarchie

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I didn't speak in wankineer - you said that a lower wattage array will give out more light if it is cooled better which in wankineer terms is incorrect. Unless you know more about LEDs than I do in which case please explain..

You're using lots of none-wankineer terms like "shonky leds" which have zero semantic content so I don't know what you're on about. Adding solid information to the thread would be really cool please.

Tim

p.s. Maximum single CPU wattage is about 300W (overclocked AMD FX) but cooling should keep CPUs down to 50 degrees (approx). LEDs can cope with more temperature, approx 80 degrees in some cases. So a CPU has to be kept at +25 over ambient and an LED at +55 over ambient. The CPU needs a lot more heat shunting. Hence I reckon a high powered water cooled heatsink should be enough.

Sorry you are not worth my time.

http://www.electronics-cooling.com/2006/11/thermal-challenges-in-led-cooling/
 

timparkin

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Sadly even your parting note isn't particularly useful as it's talking about the thermal design of LEDs as a closed unit - not the cooling of said units that the end user needs to manage.

The whole thread may have gone a lot better had you said "I don't know the facts but I think that LEDs perform better the more they are cooled" and then tried to find some information to back that up.

For instance you may have included this

Dead Link Removed

Which points out that you do get low frequency lumens loss when the junction temperature goes up. You don't get much UV loss by the looks of it though.

or perhaps

Dead Link Removed

Which shows that the lumens effiency for an LED goes down as you increase the current (not as you increase the temperature). But most high power LEDs are designed to mitigate this by have a cluster of smaller LEDS all running in parralel.

So all of this can be summarised as

1) As long as you operate within the LED suppliers suggested temperature range your LEDs will last longer

2) If you cool the LED below this you may get a very small increase in lumens output

3) If you let the LED heat beyond this then you will affect the frequency of the LED light and also reduce it's lumens output somewhat.

The manufacturers know what they're doing with high power LEDs - typically they just add more LEDs.

I didn't mean to insult you - I was just trying to get you to contribute something useful to the discussion. I know very little about LEDs and even someone who knew a hell of a lot of the physics of LEDs could still be trumped by someone with direct experience. Everybody should have something to contribute - spurious warnings of "there be monsters" doesn't help though.

Tim
 

Nodda Duma

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As someone who works in the optical industry and understands the full effects of the power levels of UV that are being tossed about here....


Buy some UV blocking goggles so you don't get cataracts.

http://m.ebay.com/itm/361234806025


$16 is a helluva lot cheaper than cataract surgery.
 
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timparkin

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As someone who works in the optical industry and understands the full effects of the power levels of UV that are being tossed about here....


Buy some UV blocking goggles so you don't get cataracts.

http://m.ebay.com/itm/361234806025


$16 is a helluva lot cheaper than cataract surgery.

Thanks Nodda - the plan was to have a closed unit but these are a good safety backup in case of accident..
 

Nodda Duma

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If that's the closed unit in the picture above...I'd keep the goggles on! :smile:

Be safe and have fun!
 

Nodda Duma

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Ah sorry, I was mixing up systems. I was referring to the image in jamespierce's post #15.

He needs goggles for sure.
 

Bob Carnie

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Tim Parkin

I saw this ad for LED unit about a year ago and I too was quite excited, now I am in the need of a larger unit than 20 x24 and am weighing the options. I can get Mercury Vapour and Metak Halide units on the used market , in fact I found a technician with parts supply in my area. These are in the price range I am at, but I really am quite interested in hearing about anyone that has used the LED approach to making Pt PD prints.

As an aside- I make silver gelatin large negatives with a Durst 76 Lambda- I can make 30 x 40 inch negatives that are fantastic for contact purpose on Silver and of course any and all other alternative process.

What interests me about the LED unit I posted about is the possibility of making a dual process unit... Silver & Pt Pd- I believe the UV units would be way too strong for silver (maybe I am wrong) and the LED technology makes me think that the adjust-ability of light output would be greater and I could purchase one machine and use it for making large Contact prints on either Ilford Warmtone or Hand Coated PT PD papers.

any thoughts on this??

Bob
 

Lachlan Young

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Tim Parkin

I saw this ad for LED unit about a year ago and I too was quite excited, now I am in the need of a larger unit than 20 x24 and am weighing the options. I can get Mercury Vapour and Metak Halide units on the used market , in fact I found a technician with parts supply in my area. These are in the price range I am at, but I really am quite interested in hearing about anyone that has used the LED approach to making Pt PD prints.

As an aside- I make silver gelatin large negatives with a Durst 76 Lambda- I can make 30 x 40 inch negatives that are fantastic for contact purpose on Silver and of course any and all other alternative process.

What interests me about the LED unit I posted about is the possibility of making a dual process unit... Silver & Pt Pd- I believe the UV units would be way too strong for silver (maybe I am wrong) and the LED technology makes me think that the adjust-ability of light output would be greater and I could purchase one machine and use it for making large Contact prints on either Ilford Warmtone or Hand Coated PT PD papers.

any thoughts on this??

Bob

A friend of mine (an electronics technician) built a 5x4 unit using commercially available LEDs - it's not really been tested out yet & we still have to work out a suitable diffusion material, but he does have artwork for a PCB that can be built up in a modular fashion using multiples of 5x4 to whatever size you want. I'll try & send you a picture later this week.

If you used RGB & UV LEDs in a suitable pattern you could easily make an exposure unit for silver & siderotype with a built in safelight. There are various electronic means of reducing light output if needed.

Heiland currently make splitgrade enlarger heads using RGB LED arrays - up to & including the massive 515 Devere head.

The only difficult/ really expensive bit is the vacuum table, but suitable items can be found in the screenprinting world.

Regarding UV exposure, a room with an interlock on the door & the on/off switch outside the door is the ultimate way of ensuring safety.
 

Bob Carnie

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I think a dual purpose Silver and Pt Pd unit would be fantastic, I actually have a 515

being able to make a vacumn table would be a piece of cake.
 
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