Re: Best proofing light
Re: Best proofing light
- Subject: Re: Best proofing light
- From: "Tony Riley" <email@hidden>
- Date: Sun, 22 Feb 2004 16:04:12 -0000
Hi All
I've been following this thread with some interest, and would like to add an
experience of mine, because it confirms James' comment.
On Date: Sat, 21 Feb 2004 21:31:56 -0800
James B. Reswick, Jr. wrote:>
>
>
I recently had a conversation with the folks at USA Lighting (where I'm
>
buying my Solux bulbs, etc.), and they said that they had been testing the
>
output voltage of different low voltage fixtures to correlate the
>
difference in the Solux bulb's spectral temperature. They found that
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fixtures could vary down to 11.5 volts, resulting in a significantly lower
>
temperature than advertised. I believe that the Solux bulb is intended to
>
be run at 12.6v. Anyone using Solux bulbs should probably measure the
>
voltage across the bulb under load, if they do not have a method of
>
accurately measuring the output spectrum.
When I was doing a dissertation on digital copying of paintings, I looked
into pushing Solux voltage-wise to get a higher colour temp. Not being an
electrical expert, I had the university physics dept. look into it with me.
It actually seems quite difficult to get absolutely consistent voltage under
load to the degree of consistency required for reliable results. I
appreciate we're talking about soft proofing here, when I was looking at
multiple (4x50w) Solux illumination for digital capture, but in the end the
Prof. and his technical staff warned me off it. They nearest they got
(theorising) was to use 2 car batteries powered down! But they were worried
about the results being invalid in scientific terms. I think the trouble is
it only takes the slightest variation in voltage to produce quite a big
variation in col. temp. I suppose the relevant thing for proofing would be
research that establishes our visual sensitivity to col. temp. variation -
what is the just noticeable difference under what circumstances ( e.g.
surroundings). I'm sure this must exist somewhere.
Very interesting thread, thanks to all.
Tony Riley
www.photosightdesign.co.uk
www.sharpedgegallery.co.uk
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