tv as a light source for a photographic application


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tv as a light source for a photographic application

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222wwwsssxxx
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Dec 10, 2005, 1:01 PM

Post #1 of 8 (1383 views)
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tv as a light source for a photographic application	Can't Post

I want to use a tv as a light source for a photographic application. I want the screen to show just a solid color everywhere. What equipment do I need to change the color of the screen and hold it at that color? Also, can I make up a simple circuit to change the color of the screen in the same way? I have built electronics in the past.

rrobor
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Dec 11, 2005, 1:07 PM

Post #2 of 8 (1375 views)
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Re: [222wwwsssxxx] tv as a light source for a photographic application [In reply to]	Can't Post

Depends on what exactly you want to do. If you want to destroy a TV to achieve this then you could just bias the outputs with switches and resistors. If not you can get a DVD test pattern disk with selections of screen colours. For photographic purposes I think you are missing the fact that the screen gets blanked out 50 or 60 times per second which could cause odd effects by using signal generators. as you have often seen a picture on a tv shown of tv picture with a black bar across it or reversing waggon wheels. Sorry but I think I would be using coloured lamps and light defusers. Other than that a monitor runs at far greater speed and monitor setup programs are freely available on the net.

222wwwsssxxx
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Dec 11, 2005, 1:28 PM

Post #3 of 8 (1373 views)
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Re: [rrobor] tv as a light source for a photographic application [In reply to]	Can't Post

Thanks for the info, rrobor! But I will elaborate a little on the application. The tv would be used as a light source for an enlarger head. In this case, the light source must be cooler than standard bulbs and floods since it is close to a negative. Being able to vary the color in the blue to green region will allow me to vary the contrast of color sensitive black & white enlarging paper. Yes, I don't care if I destroy the tv if it will accomplish this. Can you give me more specifics on adding the resistors as you mentioned? Will I have a nice wide range of color change? Also, I would like to increase the brightness as far as it will go. Any thoughts on this? Any more circuit options? Your help is much appreciated!

shadetree
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Dec 11, 2005, 4:29 PM

Post #4 of 8 (1371 views)
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Re: [222wwwsssxxx] tv as a light source for a photographic application [In reply to]	Can't Post

you can go into the service menu of the tv and change the screen color to whatever you want you don't have to bother with switches

rrobor
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Dec 12, 2005, 5:27 AM

Post #5 of 8 (1360 views)
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Re: [shadetree] tv as a light source for a photographic application [In reply to]	Can't Post

that would not give the control of luminance required and would also cause the tracking from black to white to be altered. these are bias controls to balance one colour against the other and would be very fiddley to get correct and get the control needed

shadetree
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Dec 12, 2005, 6:31 PM

Post #6 of 8 (1357 views)
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Re: [rrobor] tv as a light source for a photographic application [In reply to]	Can't Post

you can turn each color as hi or low as you want so you could easiy get the amount of luminance and shades of color needed

rrobor
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Dec 13, 2005, 8:12 AM

Post #7 of 8 (1352 views)
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Re: [shadetree] tv as a light source for a photographic application [In reply to]	Can't Post

I suggest you read the page on grey scale tracking at http://www.stevelarkins.freeuk.com/tv_grey_scale.htm to see that if the guy does what you suggests the tube will not track so he will spend an era trying to achieve what he wishes. Also if he gets a modern set with say a Philips chipset the picture will not be shown till the tracking is within certain levels. Just check the back entries of Sony with no picture. its not that simple.

shadetree
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Dec 13, 2005, 6:51 PM

Post #8 of 8 (1350 views)
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Re: [rrobor] tv as a light source for a photographic application [In reply to]	Can't Post

but he has't told us the brand of tv yet

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