Thomas Duplex Super Safelight
urahman
Hi,
I've just got hold of a second hand "Thomas Duplex Super Safelight" in
fairly good condition. I need only to change the "orange" paper filter as
part of it is either soaked on water or being kept too long in the
storeroom.
The safelight works fine..but since I am from Asia (Singapore) I cannot
get anyone to help me get the replacement "orange" filter paper.
If there's anyone of you who's using or know where I can get the email
address or fax number of the manufacturer or dealer. I be much
appreciated. The manufacturer label on the super safelight does not give
any fax or phone number.
It only has address as follows:
Thomas Duplex Super Safelight
Thomas Instrument Co. Inc.
Charlotteville
Virginia 22901
Please email me ASAP if you have any idea...
Thanks:
Urahman
--
You can access my homepage at the following address:
http://home.pacific.net.sg/~urahman
http://merlion.singnet.com.sg/~urahman
Mark Gunion
What are the filters for? The whole point of the sodium safelight, to my
understanding, is that it puts out a limited, reliably narrow energy
spectrum which isn't seen by many/most orthochromatic materials. The
spectrum is already so narrow, what is being 'filtered'? The only thing
I can guess is that they are merely to reduce the total amount of light
leaving the box and entering the room, not to further narrow the emission
spectrum. If my guess is correct, then any material (other than one
which re-emits the energy as photons at a different wavelength) should be
fine.
Can anybody fill me in on this? And maybe save our original poster some
time and money?
Mark Gunion
mwgu...@ucdavis.edu
Mark Bergman
Does someone know where to buy the replacement bulbs ? I have used this
light for more years than I care to remember and now I am in the dark.
Jean-David Beyer
Mark Bergman wrote:
>
> Does someone know where to buy the replacement bulbs ? I have used this
> light for more years than I care to remember and now I am in the dark.
I assume you could get one direct from Thomas.
If you cannot find them, call 1-800-CALUMET. They are dealers
for this light and can, no doubt, get you replacement tubes.
--
Jean-David Beyer
Shrewsbury, New Jersey
John Irvin Buford
Mark Gunion wrote:
>
> What are the filters for? The whole point of the sodium safelight, to my understanding, is that it puts out a limited, reliably narrow energy
> spectrum which isn't seen by many/most orthochromatic materials. The
> spectrum is already so narrow, what is being 'filtered'?
Thomas. The inner filter is just to touch-up the output of the light,
the outer filter is used to control the amount of light output (by
varying the size of the openings) and secondly to allow you to use it
with different materials (I can not find my instruction book).
About the bulb according to Thomas you should only replace it
with bulbs that are available as direct replacement from THomas. But, I
know that these bulbs can be had for a considerable savings from most
large electrical supply houses.
HTH
JOhn
William Patterson
Mark Bergman <BMWR...@mwci.net> wrote in article
<32F3A1...@mwci.net>...
> Does someone know where to buy the replacement bulbs ? I have used this
> light for more years than I care to remember and now I am in the dark.
>
manufacturer or is there
another source? The reason that I ask is that I bought one rather cheaply
without any bulb in it.
Thanks,
Bill Patterson (wpatt...@asap.bus.wisc.edu)
Gdoces
For replacement lamps, try:
Candela
3120 So. Croddy Way
Santa Ana, CA 92704
714-662-4900
800-722-6068
I believe that the Osram NA35W will do the trick for approximately $35
This was the information given to me by the person from whom I purchase my
used Thomas Duplex.
Gust
Arthur Silverman
In <01bc10aa$efbf2ee0$6fb65c90@user> "William Patterson"
Try the Bulbman in Reno Nevada, they sell the Sodium lamp for the
Thomas safelight for around $30.00 as opposed to Thomas' price of
$99.00
urahman
In article <32F448...@ix.netcom.com>, John Irvin Buford
<jb...@ix.netcom.com> wrote:
Hi John, any idea where I can get the replacement for the paper filter?
Since I presumed that you're using one.. maybe if you can do me a favour
by getting me the colour filter paper (orange) I'll be glad to send you
the money including postage.
Thanks
Urahman
Marc F. Hult
On Sat, 01 Feb 1997 23:55:53 -0800, John Irvin Buford
<jb...@ix.netcom.com> wrote:
>Mark Gunion wrote:
>>
>> What are the filters for? The whole point of the sodium safelight, to my understanding, is that it puts out a limited, reliably narrow energy
>> spectrum which isn't seen by many/most orthochromatic materials. The
>> spectrum is already so narrow, what is being 'filtered'?
> This is basically true. There are two sets of filters on the
>Thomas. The inner filter is just to touch-up the output of the light,
>the outer filter is used to control the amount of light output (by
>varying the size of the openings) and secondly to allow you to use it
>with different materials (I can not find my instruction book).
>
> About the bulb according to Thomas you should only replace it
>with bulbs that are available as direct replacement from THomas. But, I
>know that these bulbs can be had for a considerable savings from most
>large electrical supply houses.
A low-pressure sodium vapor bulb does have light output dominated by
the 589 nanometer sodium ("D" ) peak. Although sodium vapor has a
discontinuous bright-line emission spectrum, solid or liquid sodium
has a continuous spectrum over a range of wave lengths like a tungsten
filament. The changing output characteristics of the bulb can be seen
as it warms up and the sodium vaporizes. A LP sodium bulb also
contains a noble gas (argon or neon) at 1/20 of an atmosphere pressure
or so. In the Thomas safelight, the filter helps to minimize the
potential for fogging as the bulb (and the sodium) heats up but you
still can't just turn on the safelight on and open up a box of paper
-- at least under the conditions in my darkroom.
Thomas sells the safelight with a primary filter for variable contrast
black and white paper. which is similar to a Kodak OC and a secondary
filter which is either light red for ortho materials (similar to a
Kodak 1A) or for color materials (similar to a Kodak 13). These
filters are used as John describes.
Thomas Duplex filters I've seen consist in sandwich of two pieces of
glass with a gel/cellophane type filter and some additional paper. A
couple/three of layers of red rubylith (ruby or red-colored masking
film) makes a good substitute for the red filter material. Amber
masking film is available which should work for the primary filter
although I haven't tried it. These are available from Freestyle
www.freestylesalesco.com (800-292-6137). Note that this film is in
their Graphics catalog, but not in their photo catalog.
I replaced the worn-out filter in mine with a Kodak glass OA filter
(which is for graded papers and not suitable for multicontrast paper
with a tungsten bulb) which I cut down from 10x12". Works fine.
These safelights put out an outrageous amount of light. I have one
mostly throttled down in a far corner and it still illuminates an
8'x14' room to what seem unfairly bright conditions. Reflections off
of the many white surfaces in my darkroom assure that most work areas
are illuminated with minimal shadows except near the enlarger which
I've purposely partially blocked off. Real darkroom denizens doubtless
use 7-1/2 watt bulbs in bullet safelights, but I wouldn't willingly
revert to working in their little pools of light. Typically, they seem
to be arranged so that illumination levels are highest where they
should be lowest in order to avoid fogging.
Bulbs (sox 35) are available for $36 from Gray www.graysupply.com
(800-top-bulb) as well as other bulb suppliers.
HTH ... Marc
Marc F. Hult
hu...@cinternet.net
lin...@aol.com
In article <5cukj7$o8i$1...@mark.ucdavis.edu>,
ez05...@bullwinkle.ucdavis.edu (Mark Gunion) writes:
>From: ez05...@bullwinkle.ucdavis.edu (Mark Gunion)
>Date: 1 Feb 1997 05:33:27 GMT
>
>What are the filters for? The whole point of the sodium safelight, to
my
>understanding, is that it puts out a limited, reliably narrow energy
>spectrum which isn't seen by many/most orthochromatic materials. The
>spectrum is already so narrow, what is being 'filtered'? The only thing
>I can guess is that they are merely to reduce the total amount of light
>leaving the box and entering the room, not to further narrow the emission
>spectrum. If my guess is correct, then any material (other than one
>which re-emits the energy as photons at a different wavelength) should be
>fine.
>
>Can anybody fill me in on this? And maybe save our original poster some
>time and money?
>
>Mark Gunion
<<<A low-pressure sodium vapor bulb does have light output dominated by
the 589 nanometer sodium ("D" ) peak. Although sodium vapor has a
discontinuous bright-line emission spectrum, solid or liquid sodium
has a continuous spectrum over a range of wave lengths like a tungsten
filament. The changing output characteristics of the bulb can be seen
as it warms up and the sodium vaporizes. A LP sodium bulb also
contains a noble gas (argon or neon) at 1/20 of an atmosphere pressure
or so. In the Thomas safelight, the filter helps to minimize the
potential for fogging as the bulb (and the sodium) heats up but you
still can't just turn on the safelight on and open up a box of paper
-- at least under the conditions in my darkroom.
<<snip snip>>
HTH ... Marc
Marc F. Hult
hu...@cinternet.net>>>>
As Marc points out, the emission spectra of sodium is dominated by the 589
line (actually a doublet). My CRC handbook of Chemistry & Physics list 15
other emission lines for sodium in the visible (400 to 700 nm) range of
the spectrum. 588.9 is the brightest followed by 589.6 -- about half as
intense as the 588.9 line. These two lines give the lamp its
characteristic yellow color. 498.3 and 466.9, in the blue-green portion
of the spectrum are listed as approximately 10% as intense as 558.9.
These lines, along with several other blue lines, would have an effect on
VC papers, hence the need for filtration. Even if the lamp were
compleatly up to temperature, there is still a need for filtration due to
the discontinuous nature (i.e. the multiple emission lines) of emission
spectra.
Kirk Keyes
Marc F. Hult
On 10 Feb 1997 15:32:33 GMT, lin...@aol.com wrote:
SNIP: Previous posts deleted
>
>As Marc points out, the emission spectra of sodium is dominated by the 589
>line (actually a doublet). My CRC handbook of Chemistry & Physics list 15
>other emission lines for sodium in the visible (400 to 700 nm) range of
>the spectrum. 588.9 is the brightest followed by 589.6 -- about half as
>intense as the 588.9 line. These two lines give the lamp its
>characteristic yellow color. 498.3 and 466.9, in the blue-green portion
>of the spectrum are listed as approximately 10% as intense as 558.9.
588.9?^^^^
>These lines, along with several other blue lines, would have an effect on
>VC papers, hence the need for filtration. Even if the lamp were
>compleatly up to temperature, there is still a need for filtration due to
>the discontinuous nature (i.e. the multiple emission lines) of emission
>spectra.
>
>Kirk Keyes
Emission spectral data are commonly available for flame, spark and arc
sources at atmospheric pressure and for vapor in lamps at reduced
pressure. It is the latter data that are pertinent. For example, flame
spectra have NaO lines completely absent in a vapor lamp, and relative
intensities for the lines that are common between sources can vary
greatly. The 498.3 and 466.9 lines are major components of a sodium
arc spectrum and doubt that they are anywhere near 10% of the output
of a low-pressure sodium bulb. But as we both wrote, there are other
lines which contribute to the need for a cuttoff filter. Actual bulb
manufacturer's data would presumably also include contributions from
neon or argon.