Re: 5000° K Full Spectrum Lighting
Re: 5000° K Full Spectrum Lighting
- Subject: Re: 5000° K Full Spectrum Lighting
- From: Koch Karl <email@hidden>
- Date: Wed, 27 Feb 2008 08:56:25 +0100
Hi Richard, Danny,
Am 26.02.2008 um 23:33 schrieb dpascale:
Richard,
Do you intend to illuminate the area around your monitors with 5000
K light?
That´s wha´s recommended in ISO3664 and 12646
If yes, are your monitors also at D50? (or somewhere between D50 and
D60)
again, ISO 12646
Do you intend to compare your prints against your monitor? If not,
then buy these low cost tubes and keep the ambient level low (100
lux recommended). If yes, read what follows.
Even lower, if you want a good comparison, your viewing light must e
500 lx ± 125 lx (ISO3664), this requires a monitor luminance of 160 cd/
m2 (± 40) and your ambient light must be below 64 x and should be
below 32 lx.
The required illumination for correct viewing assessment, 500 lux+,
is too high to be used as ambient (even your 390 lux is way too high
for many).
This is absolutely correct, because the ambient light drastically
reduces the contrast ratio on your monitor.
Thus, you need a separate, somewhat confined, viewing booth. You
will also need to adjust your booth light output so that the
luminance of the viewed print matches your monitor luminance
(typically 100 to 160 cd/m2).
with 100 being too low, the range is 120 to 200 cd/m2)
If you compare your prints under a 5000K lamp near your monitor,
your monitor better be at 5000K also. If your monitor is "far away"
from your viewing booth, a D65 calibrated monitor will be OK.
If you critically compare printed material with printed proofs,
without a need to compare the prints against a nearby monitors, then
a room full of fluorescents at 5000 K, with much more than 500 lux,
is the way to go (2000 lux is recommended, which is quite bright !).
… but typical for a standard viewing booth.
You better use less of the more expensive fluorescents and place
them at select locations where they do not interfere with the
monitors (a booth, or a low hanging fixture is preferable to a
ceiling fixture). And keep all the other lights off (the window
shades also if applicable). The indirect illumination from the booth
areas should be enough to work comfortably. If not, individual desk
lamps should be used when required.
Keep in mind, though that the lamp fixtures – reflectors, deflectors –
also have an influence on the spectrum. So, a professionally made lamp
with certified (close to) D50 light would be the first choice. BTW,
D50 is not a full, smooth spectrum, but a specified spectral curve
(quite jaggy) that cannot be technically reproduced (within reasoable
effort). 5000K Planck is a smooth curve.
And, finally, to add to what Andrew mentioned, fluorescents are
fluorescents (!), even the best ones are not perfect, imagine the
second tier...
Danny Pascale
email@hidden
Best,
Karl Koch
----- Original Message ----- From: "Richard Frederickson" <email@hidden
>
To: <email@hidden>
Sent: Tuesday, February 26, 2008 4:14 PM
Subject: 5000° K Full Spectrum Lighting
My manager and I have had an ongoing discussion for some time now
regarding whether or not 5000° K lighting is justifiable in our
illustration/photography workstation areas. We do some prepress
work and I have a GTI viewer at our scanning workstation. Most of
our material is printed in-house (e.g., scientific posters) and our
color is important, but not critical.
The folks at GTI quoted me a price of $23 a lamp, which my boss
absolutely will not go for. I've seen a number of "Full Spectrum"
lamps on the market that are the same color temperature for as
little as $6 a tube, and I'm thinking that something is better than
nothing. Am I right in this line of thinking and how prevalent is
full spectrum lighting in the real world?
Also--beyond color fidelity issues--are there any additional
benefits documented about working in this lighting environment?
The corollary question is how bright should the working environment
be? I took few quick measurements around the office with my eye-one
found a value of 74 Lux at the monitor is about 390 Lux at the
keyboard and quite comfortable to work in.
Many thanks for your thoughts,
Richard
--
Richard Frederickson (Contractor)
Scientific Publications, Graphics & Media (SPGM)
Advanced Technology Program, SAIC-Frederick, Inc.
National Cancer Institute at Frederick
Post Office Box B
Frederick, MD 21702
Phone: (301) 846-1546
FAX: (301) 846-6563
email@hidden
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