[argyllcms] Re: How to create .sp files with an i1 Pro?

  • From: Ben Goren <ben@xxxxxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Thu, 13 Sep 2007 21:31:40 -0700

On 2007 Sep 12, at 2:09 AM, Graeme Gill wrote:

> There  is a  rather  large disparity  between  the Graphic  Arts
> standard Illuminant  D50, and the  sort of lighting  most people
> use indoors. Even  the higher  quality 5000K  Fluorescent lights
> don't have  a spectrum  that much resembles  D50, and  the Ultra
> Violet content of the lights  is another wild card when combined
> with Fluorescent Whitener Additive in  paper stock, since the UV
> output is often not closely controlled.

You ain't  kiddin'! A year  or two  ago, I  ordered a  handfull of
compact fluorescent bulbs advertised as  being 5000K with a CRI of
92. I  plugged them  into  the living  room, rather  excited...and
immediately  thought...``Gee, they  sure seem  somehow hollow  and
excessively blue.''

So, I immediately broke out the i1...and, sure enough, they were a
perfect match for one of the standard F illuminants whose spectrum
is  so bad  that  the G-M  share tool  couldn't  even calculate  a
temperature for it -- let  alone a CRI. Fortunately, the company I
bought them from only gave me a minor hassle to return them.

The only  difference with  most of  the rest of  the lights  in my
apartment is that  they're reddish - yellowish  - orangish instead
of bluish...and they cost a fraction  of what the ``CRI 92'' bulbs
did. The  kitchen, I've  mentioned, has  tubes that  (according to
G-M)  really  *do* have  a  CRI  of  about  92 (I  forget  exactly
what). It's good  enough for a ``rough  guess'' sort of look  at a
print, but for real evaluation I step outside.

> The  closest  practical  lighting are  filtered  Quartz  Halogen
> lamps, such  as Solux <http://www.solux.net/>, although  I'm not
> sure that  the UV content is  the same as real  D50 daylight (in
> fact they seem  to boast that it has low  UV output, making them
> rather unsuitable for viewing substrates with FWA under standard
> D50 conditions.)

I've spent  a lot of  time over  the years looking  for affordable
quality  lighting. The  Solux  lights are  tempting...but  awfully
expensive.

I'm currently  toying with getting  some Lumiram Ecolume  CF bulbs
for ``normal'' lights  (they claim 5000K and a CRI  of 96), plus a
pair of  their 6500K CRI  98 tubes for the  kitchen. They're cheap
enough that I won't get too upset so long as the CRI is over 90. I
figure they'll be much, much better  than what I have now, even if
they're not in the same  league as a skylight. (The landlady might
complain  if I  started cutting  holes in  the roof,  as would  my
wallet....)

If the tubes are as good as  they claim, I'll probably even make a
viewing  booth from  them, and  maybe also  a softbox. But  that's
probably just wishful thinking.

Cheers,

b&

P.S. I  took samples  of the  light in  the gallery  at the  Tempe
Library where my  pictures will be shown in  a couple months. I've
got the .txt files to make .sp files, and G-M says they're a close
match  to  a standard  ``A''  illuminant. Good  thing I  took  the
samples.... b&

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