[alt-photo] UV exposure box

[Andy Schmitt]

Hi All
Yep...I said I was building a small one...and still am.
The LED's I picked up are kind of high on the spectrum but should work from
Gum.
When I contacted the gentleman I purchased them from he said lower spectrum
lights were available but they would have to do a run of them & it just got
too expensive to pursue.
I am STILL soldering away..... A lot of joints in a small space. If I was
better at PC Board design I would have laid out one. Would have made it
much, much easier...
regards 

Andy Schmitt
           Photographer, Computerist, Slayer of Dragons 
      All opinions expressed are mine...Unless otherwise stated or REALLY
stupid
Head of Photography, Peters Valley Craft Center
2011 schedule available on line at: 
    http://www.petersvalley.org/2011courses.html#photo




Message: 6
Date: Fri, 11 Mar 2011 21:28:37 -0500
From: etienne garbaux <photographeur at nerdshack.com>
To: The alternative photographic processes mailing list
	<alt-photo-process-list at lists.altphotolist.org>
Subject: [alt-photo] Re: LED exposure lights
Message-ID: <20110312022846.7513311B9A8 at karen.lavabit.com>
Content-Type: text/plain; charset="us-ascii"; format=flowed


>Good question and I think there is some discussion on this in the 
>archives, but mostly speculation.

There was a short thread in early December 2009 that started with a 
question about using a UV LED as the source for a UV 
densitometer.  Andy Schmitt noted that some DIY printed-circuit 
constructors use homemade UV LED light boxes to expose the etch 
resist, and that he had bought supplies to make a light box for photo 
use.  I do not believe he has reported on his results.

>I have done some web searches and there are LED lights for UV that 
>are very narrow in spectrum range and tuned to very specific UV 
>values.  They are still expensive, but that may change in the 
>future.  I'm not sure that they put out enough light though.

Well, it depends on how many you use.  If you pack them together as 
tightly as possible (which would require from 5,000 to 10,000 LEDs to 
make a 16x20" light box, depending on their size) and place the array 
within an inch or two of the media, I suspect there would be plenty 
of light.  (This is what the PC constructors do, but their exposure 
boxes are generally no larger than 5x7".)  If you want to expose 
16x20 prints with an array of 100, probably not.  There are plenty of 
good candidate LEDs with peak outputs around 400 nM for less than a 
dollar each (here's one for $0.66: 
https://www.alliedelec.com/Images/Products/Datasheets/BM/VCC/398-0973.PDF. 
Some assembly required.     ;-)

Best regards,

etienne


regards 

Andy Schmitt
           Photographer, Computerist, Slayer of Dragons 
      All opinions expressed are mine...Unless otherwise stated or REALLY
stupid

             Great new Products, Wearable's, etc at: 
            http://www.cafepress.com/schmitthouse

Head of Photography, Peters Valley Craft Center
2011 schedule available on line at: 
    http://www.petersvalley.org/2011courses.html#photo