oil immersion?

Sorry, but I don't know what to call it - the technique where one immerses
the negative in a fluid in order to surpress dust. Pointers to
information?

Check under "Carlwen" he
http://www.phototechmag.com/buying_drkroom.htm
This information was published in 1998 so I don't know if it's still
current. njb


On Wed, 11 Feb 2004 18:53:02 -0600, (jjs)
wrote:


Sorry, but I don't know what to call it - the technique where one immerses
the negative in a fluid in order to surpress dust. Pointers to
information?

In article , Nacio Jan Brown
wrote:

Check under "Carlwen" he
http://www.phototechmag.com/buying_drkroom.htm
This information was published in 1998 so I don't know if it's still
current. njb

Very helpful, thank you. It turns out they are currently listed, and by
gosh, right here in my home state.

"jjs" wrote in message
...

Sorry, but I don't know what to call it - the technique where one immerses
the negative in a fluid in order to surpress dust. Pointers to
information?

Ctein wrote in _Post Exposure_ about using Edwal No-Scratch on the whole
negative to reduce dust. If you have the book, his explanation was pretty
convincing, but I haven't needed to do it yet. I wonder if the stuff will
act as a dust magnet, however. PEC-12 removes it.

Edwal's No-Scratch should be in every darkroom. I've always had a bottle
next to the enlarger (replace when it begins to yellow). It smells like
turpentine and in fact, I think that is what it is (was) made of.



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(jjs) writes:

Sorry, but I don't know what to call it - the technique where one immerses
the negative in a fluid in order to surpress dust. Pointers to
information?

Wet Gate Printing. Invented in the end of the 70s, early 80s for
printing release prints of movies.

--
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+61 (08) 9257-1001 Kalamunda.
West Australia 6076
comp.os.vms,- The Older, Grumpier Slashdot
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On Wednesday 11 February 2004 04:53 pm, jjs wrote:

Sorry, but I don't know what to call it - the technique where one
immerses the negative in a fluid in order to surpress dust. Pointers
to information?

You're referring to an oil negative carrier, the primary advantage of
which is the elimination of scratches on the negative. Any dust just
floats off.

Traditional oil carriers are VERY messy. It uses real oil, but a
special type, that has the same index of refraction as the film base.
The negative HAS to be cleaned after printing. Some time ago -- 20
years, IIRC, there was a company (in Texas???) that had come out with
an "oil" that worked just as well as the traditional oil, but would
evaporate from the negative, when set aside after printing and, thus,
no cleaning was required.

--
Stefan Patric

Wet Gate Printing. Invented in the end of the 70s, early 80s for
printing release prints of movies.


Actually wet gate printing has been around for the last 100 years. Some gates
use oil and some others, a sort of dry cleaning fluid. In most motion picture
work, they use 100 proof grain alcohol and true the motion picture industry
started using it in the early 80's

Larry

The other "messy" part is that any dust that falls on the negative is going
to stick to the oil and you won't be able to blow it off.

--
darkroommike

----------
"Stefan Patric" wrote in message
news:e%7Xb.1296$Mf.1262@okepread04...
On Wednesday 11 February 2004 04:53 pm, jjs wrote:

Sorry, but I don't know what to call it - the technique where one
immerses the negative in a fluid in order to surpress dust. Pointers
to information?

You're referring to an oil negative carrier, the primary advantage of
which is the elimination of scratches on the negative. Any dust just
floats off.

Traditional oil carriers are VERY messy. It uses real oil, but a
special type, that has the same index of refraction as the film base.
The negative HAS to be cleaned after printing. Some time ago -- 20
years, IIRC, there was a company (in Texas???) that had come out with
an "oil" that worked just as well as the traditional oil, but would
evaporate from the negative, when set aside after printing and, thus,
no cleaning was required.

--
Stefan Patric

ObContEd:

Oil immersion has applications in imaging beyond scratch 'n dust.

The oil allows a 50% increase in numerical aperture, with a
corresponding increase in resolution with decreased diffraction.

A little javap from Nikon shows the effect of immersion oil
in a microscope:

http://www.microscopyu.com/tutorials...ion/index.html

To bad Nikon doesn't have a 'photographyu'.

--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics; Informatics; Photonics.

"Nicholas O. Lindan" wrote in
message
ink.net...
ObContEd:

Oil immersion has applications in imaging beyond scratch
'n dust.

The oil allows a 50% increase in numerical aperture, with
a
corresponding increase in resolution with decreased
diffraction.

A little javap from Nikon shows the effect of immersion
oil
in a microscope:


http://www.microscopyu.com/tutorials...ion/index.html

To bad Nikon doesn't have a 'photographyu'.

--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics; Informatics; Photonics.

Oil immersion for microscope objectives is a different
thing from wet gate printing. The oil used has an index of
refraction higher than air so the angle of incidence at the
entrance pupil of the objectective can be larger. An actual
oil is used. Wet gate printing uses an alcohol. The index of
refraction is chosen to be near that of the support. So, the
liquid fills in the scratches on the support with a material
which does not diffract light at the scratches. There have
been several solvents used in the past, most of which are
now considered environmental hazards. 1,1,1,trichlorethane
and perchlorethane were common for this application as well
as film cleaning. Now very dry Isopropyl alcohol is used for
both cleaning and wet gate printing.
Because the liquid matches the support its most effective
on scratches on the back of the film. It has little benefit
for scratches in the emulsion. Emulsion scratches tend to
disrupt the image anyway so even a liquid matching the index
of the gelatin would be of limited benefit.

--
---
Richard Knoppow
Los Angeles, CA, USA