Nice post Mark,
I didn't know the 1/8"-per-PAR code, and I've been around those bulbs for
almost 50 years.
A few nice things have happened in the past few years, so that almost anyone
who is partially-technically-inclined can become their own lighting expert
[in time].
X-Rite has come out with a new version of its i1Pro, a very useful color
spectrophotometer [the new i1Pro2 go for $1100-1800]. This means that all
the older models [the kind I have used for 12 years] are showing up on eBay
for $400-600 Buy-it-Now; I think I paid $1500 for my first one.
When used on a laptop via a USB port [with the all important white dome
ambient light attachment] with Robin Myers' SpectraShop software ($50-95)
you can measure the color temperature of any light source even "dimmed"
incandescent, LED lamps in the showroom and daylight through windows of all
types with light reflecting off all colors of surfaces and all times of the
day. This measurement tool and software can measure the actual color
temperature [in degrees Kelvin] and in two flavors of CRI (8-patch and the
more accurate 16-patch version) with spectral output, or as a set of XYZ,
Lab or RGB (given the RGB Color Space such as Adobe RGB 1998) numbers. The
spectra reveal presence of UV, spikes due to mercury and phosphors in
fluorescent bulbs and the UV content in white LEDs. Daylight and
incandescent light sources generally have smooth spectra with few humps and
spikes; they render color very nicely.
The issue with the humps and spikes in a light sources or lamps spectra, is
that while the spectral features can't really be seen on a white/gray
reflector card, they tend to overexcite particular colors in favor of others
skewing "display" color. The CRI has some value here [8-patch version is
used by most manufacturers because it give more favorable results, while
still being an "official" tool], but the 16-patch version is far better --
its all in SpectraShop v4. SpectraShop can also be used to show several
spectra at the same time, subtract one from another, and to convert one bit
of color data to any other color property and much more. [What did you do
without it?]
This will open your eyes and make you an expert, after some months of daily
use. Make sure your used i1Pro is not (a) the Display model and (b) is the
UV-cut version, and, DOES INCLUDE the light diffuser dome attachment, in its
2" x 2" x 3/4" black clamshell case. There are many more attachments good
for other applications such as measuring the color of a particular thing in
a 1.5 mm spot, and calibrating [all] your computer monitor(s). However, it
won't yet work on your iPad even though it has a USB port; Myers' is working
on this, but its the drivers from X-Rite and iPad-OS.
Tim Vitale
Conservator
Oakland, CA
510-594-8277
________________________________
From: Museum discussion list [mailto:[log in to unmask]] On Behalf
Of Marc A Williams
Sent: Thursday, July 05, 2012 10:36 AM
To: [log in to unmask]
Subject: Re: [MUSEUM-L] PAR lightbulb ban
Jamin,
I believe you are referring to potential changes in incandescent light bulb
(properly called "lamp" by lighting professionals) availability. Please see
the following link for more information.
http://en.wikipedia.org/wiki/Phase-out_of_incandescent_light_bulbs and also
http://en.wikipedia.org/wiki/U.S._Lighting_Energy_Policy The PAR refers to
"parabolic aluminized reflector" and is the type of bulb construction, not
the type of lighting source (incandescent, fluorescent, LED, etc.). The
number refers to the diameter in 1/8s of an inch. So, PAR 38 is 4.75 inches
in diameter. Please see this link for more information on PAR.
http://en.wikipedia.org/wiki/Parabolic_aluminized_reflector_light
Since the size and the design of the bulb are independent of the type of
lighting source, you should still be able to use your fixtures if you want
to. The primary considerations (I apologize for redundancy with previous
posts) are wattage versus light output [efficiency], color temperature of
the light (generally 2800-6500 degrees kelvin, with daylight defined
generally as between 5500 and 6500 degrees kelvin), color rendering accuracy
of the bulb (CRI, with 100 exactly reproducing daylight at that color
temperature), amount of ultraviolet light (UV) emitted, with virtually zero
being ideal, and anticipated lifespan of the bulb. Each type of lighting
source has its advantages and disadvantages. Most incandescents use a
relatively high amount of energy, have low color temperature (reddish
light), put out virtually no UV, and have a short lifespan. Fluorescents
are fairly efficient, have varying color temperatures, are generally poor in
CRI, although there are some exceptions, emit a lot of UV light (this can be
filtered with straight bulbs, but is very difficult with spiral bulbs), and
have a moderately long lifespan, but their output drops off with hours of
use. LEDs are very high efficiency, currently can have varied color
temperature, although earlier versions were very high (blue) historically,
have had relatively poor CRI, and have high lifespan. However, studies on
LEDs show that their characteristics change with hours of use, and effective
lifespans for museums are much shorter than advertised.
You are correct that the technology is changing fast, and in a matter of
months or a few years, the situation may have changed completely. LEDs may
be the future, but from most perspectives, they are not quite there yet for
museum use. However, with the phased-in nature of the changes (between 2012
and 2014 in the US), LED technology may be adequately improved by the time
you need to buy replacement bulbs. Or, another technology may be available.
BTW, the law does not require phasing out incandescents, but provides for
increased efficiency standards, so it is possible they may still be
available only more efficient, or, alternatively, manufacturers may stop
making them if their efficiency can't be improved. And, as I understand it,
the law only applies to incandescents between 100 and 40 watts. PAR 38s are
likely to be available with different lighting sources even if the
incandescent version is phased out.
The overall issues are much more complicated and nuanced than this response,
so please do further research to fully understand the issues and
possibilities. Good luck!
Marc
American Conservation Consortium, Ltd.
4 Rockville Road
Broad Brook, CT 06016
www.conservator.com
860-386-6058
Marc A. Williams, President
MS in Art Conservation, Winterthur Museum Program
Former Chief Wooden Objects Conservator, Smithsonian Institution
Fellow, American Institute for Conservation (AIC)
----- Original Message -----
From: Jamin Landavazo <mailto:[log in to unmask]>
To: [log in to unmask]
Sent: Thursday, July 05, 2012 12:42 PM
Subject: [MUSEUM-L] PAR lightbulb ban
Hello listers –
Our maintenance person just informed me of an e-mail he was sent
regarding a ban on PAR lightbulbs – one of the types that we and presumably
other museums use in track lighting fixtures for galleries. The ban will go
into effect on July 14th, 2012, after which no one will be able to
manufacture these bulbs in the US. Distributors will be allowed to sell
their remaining stock.
My questions for the list – in the ever-changing world of museum
lighting, what bulbs would you suggest to replace our current PAR 38s? We
will need to eventually replace about 350 throughout our galleries, so cost
is an issue. However, we are not completely opposed to a higher up-front
cost if certain bulbs really do last longer and therefore cut down on the
number of bulbs we purchase and the staff time to replace them. Are LEDs
the way to go? Have color rendering issues been resolved to museum
satisfaction? What other cutting edge (or not) options are there that
museums have used successfully themselves?
I have searched the listserv and looked at the many of the lighting
discussions, but with the rapidly changing nature of the lighting world and
in light of the recent ban, I figured one more post couldn’t hurt. Bonus
points for the “plain English” explanations!
Thanks in advance,
Jamin Landavazo
Chief Curator
Reno County Museum
100 S. Walnut
Hutchinson KS 67501
(620) 662-1184
Kansas Underground Salt Museum
3504 E. Ave G
Hutchinson KS 67501
(620) 662-1425
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