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cold cathode lighting

Posted by George Creighton  
cold cathode lighting
December 19, 2010 10:59PM

have just discovered the joys of cold cathode mineral photography, three months without direct sunlight here makes for constant light source experiments.

the photo above is an old pc lcd monitor( some electronic know how required ) with the pol. and diffusion filters removed, then reassembled with the thick plastic bit that holds the cold cathode tubes in place on its head so it can be pointed down also the stand swivels horizontally. connect it to a pc graphics card ( vga out ) with the timer set for at least 30 minutes... the camera is a dsr used only for this demo, taken with a canon powershot g11 used for all my photos!

the above photo is a neutral grey hairy army blanket used in all my photos, taken with my canon g11 and is not corrected in anyway just copyrighted.

the main thing is that you have a colour calibrated screen to veiw your photo results on.

Sorry if this subject has appeared before but could not find a reference to this theme ( mods please delete if mentioned before ).

Regards george

ps hope this makes sense?
avatar Re: cold cathode lighting
December 20, 2010 01:12AM

Maybe I have been in the dark too long. I see what you have done, but I'm not sure why, but I am probably not seeing the obvious. How does this produce a color calibrated screen to view your photo results on? I assume that the LCD layer is no longer in the panel.

Otherwise, cold cathode lamps are just ordinary mercury lamps with a phosphor coating the inside of the tube. I should think that a couple of mv lamps and a diffuser would work as well. Pardon my dim old mind, but what am I missing here.

avatar Re: cold cathode lighting
December 20, 2010 03:00AM
Gene, not just you, I am missing it as well, lol. I am somehow missing the 2+2=4 part of the statement.

FYI, for a totally nice spectrum lightsource, as full as full can get, a simple Solux bulb does the trick. I use PAR30's 3500K bulbs. Also, for those on a budget, 2-3 Ott-Lite HD 6500K bulbs work great and are only like $5-$6/ea and the 8" dome clamp on shop lights from Wal-Mart are only like $6/ea.

They do make light panels for photography that are cold cathode, or at least used to, as well as videography. They make similar panels that are LEDs as well.

Registered Gemologist
Research Gemologist
Club President/Owner
Re: cold cathode lighting
December 20, 2010 03:58PM

as you can see from the attached photo there is a great big mountain to the south of my house going east to west.

house 220 meters above sea level
top of mountain 738 meters above sea level base of mountain 600 meters from house top 900 meters from house,,,, hence the sun is absent from 1november until 2nd week in february ( 14 weeks ).

so i needed a reliable lightsource for this time of year to continue taking photos of the minerals i collected in the summer.

as you state Gene

cold cathodes are mv super thin tubes
yes the only things remaining in the monitor are the electronics the backlight plate as well as the lamps

now i have this light source ( 18/12-10 ) am having fun as i do not need to correct the colours on my ( colour calibrated ) laptop as much, as i did with the iffy available light before.

as im on a tight budget i used only what i had to hand ( no purchase ).

they are phasing out incandecent lamps here.

hope this explains my partial madness, but feel free to ask for more details.

Regards george
avatar Re: cold cathode lighting
December 20, 2010 04:46PM
My biggest question is, why did you copyright a carpet???? Is it a special carpet? Is the photo at risk of being stolen? :)
Re: cold cathode lighting
December 20, 2010 06:13PM
hairey grey blanket not carpet!!!!!!!!!!!!!

military ( royal engineers ) issued to me in 1967 and still in my possesion,,, travelled all around the world with me,,, if its stolen will give a copy of that photo to the police to do a fiber match using forensic identification.... as seen on csi.

jokeing apart i copyright all my photos as everyone should,,,, because i do this have had many requests for my ( diverse ) photos for books, leaflets and magazines.

who knows that photo might be worth a fortune in the future ( notice the yellow bit below and to the right of the copyright )

Regards george
avatar Re: cold cathode lighting
December 20, 2010 08:40PM
This photo of a carpet is worth a fortune. Maybe because it's a large (174.5 x 210 cm) print, or whatever.
avatar Re: cold cathode lighting
December 21, 2010 02:21AM

I think I get it now. It doesn't look like there would be a Fry's Electronic Super Market just down the road, like I am accustomed to. In fact, looking at the view and your mention of lack of sun, I have to compliment you on your ability to remain sane. Rather than using the panel for photography, I would be sitting in front of it to boost my vitamin D and serotonin levels to try and keep them from going off the end of the dipstick.

avatar Re: cold cathode lighting
December 21, 2010 07:48AM

Your place looks heavenly - I imagine very cool (probably exceedingly cold in winter) and so wonderfully quiet

I'd love it

Re: cold cathode lighting
December 24, 2010 09:00PM
Gene,,,,, masses of cod liver oil not flavoured,,, drink it from the bottle,,, love itsmileys with beer

Keith,,, lived here since i buildt the house in 1998 even drew the plans,,,,, love the solitude,,, nearest neighbour over the river through the forest 1500 meters and thats the short cut,,, correct with temp,today -25 out +22 in now,,, but not long to spring then new mineral season...X(

Wishing too all seasonal greetings.

Regards george
avatar Re: cold cathode lighting
January 31, 2011 06:59AM
FYI, Ott-Lite HD CFLS are not incandescent light, they are compact florescent bulbs. Solux also makes MR-16 replacement bulbs as well which work just as well too.

As long as lighting has a fairly smooth spectrum most cameras will not have issue matching the colors seen. But, they may not be all the colors normally seen in true full spectrum lighting like in the sun.

Registered Gemologist
Research Gemologist
Club President/Owner
Re: cold cathode lighting
April 07, 2011 06:23PM
At last spring!!!!!!!!

Photo taken 7/4-2011 ,,, 1945cet

Still snow here and there, but sure sign of spring the river ( 25 meters from house ) is at last in spring flood washing down from the mountains new mineral finds for me to discover in the summer (:D

Regards george

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