From: JEFFREY PAULL (email suppressed)
Date: Sun Jun 14 2009 - 03:19:51 PDT
Hi, Myron,
YOUR FIRST QUESTION
You are saying that the grey base of track neg. stock is not subject to chemical lightening.
That grey look then is not simply a partial exposure. Was that always the case even on older track neg stocks?
Here's what I know, maybe some of this can fill in what you already know.
The grey base of B&W neg stocks and I THINK, sound track stock, is in the plastic itself. Can't be washed or soaked out.
Shooting B&W neg in a camera means pointing it, sometimes, at scenes with immense intensity range,
for example, streetlights at night. Some of that blasty light hits the emulsion and continues through to the base
and also through the base itself to its inner back side.
Then it reflects back to the emulsion, but it's now spread out. So you get the glow around the streetlights.
Even without dazzling lights, this bounce back light can erase fine details sort of like a dirty lens can.
So they dye the plastic grey to absorb at least some of that stray light.
Since neg is nver projected, they don't have to worry about diming the picture. (In using positive stocks they DO worry, so the base of positive stocks is clear.)
The grey doesn't have to be very dark because that excess light gets filtered twice: once hitting through the base to the back surface,
and again as it's reflected back through it to the emulsion.
The grey base also prevents "light piping": When you are loading a 100' roll in a camera even in subdued light,
some light will hit the edges of the plastic and enter the base. Once the light's inside,
it will stay inside, bouncing around as an "internal reflection".
Optical fibres for communications exploit this internal reflection, but in movie film, it could cause edge fog beyond the run-off footage.
So the grey plastic base does double duty and absorbs this edge-fogging light as well.
Filmstocks with Mylar/Estar plastic base are more prone to light-piping than acetate base.
Colour films (since early '60s) deal with halation in a different way.
The plastic base of colour films is transparent, but a coating of carbon black is painted on the back side of the base
when it's manufactured. This layer, being opaque, is extremely efficient at absorbing this excess light.
After exposure, it's served its purpose and has to be removed to make the film transparent.
The developing machines remove this coating as a 1st step in development by scrubbing or blasting it off with water jets
so none of the black particles contaminate the next developing stages.
The black layer is called a "rem-jet (removed by jets of water) layer".
Kodak invented it and since they also invented the film and the developing processes, and had probably, at that time a 90% hold on the market,
they could use this coating and the make its removal a requirement of any development machines that would be manufactured.
The B&W developing machines had been in use for decades before the rem-jet method was invented,
so to sustain compatability, it wasn't appled to B%W films.
SECOND QUESTION
> Incidentally, what might the track sound like after some paint falls on it?
instant avant garde sound composition....lol. hmmmm. I think my next film may already be in the works here.....
Myron, have you come acoss the animation of Norman Maclaren, yet?
He and Len Lye in the '30s were the originators of scratching/painting on film.
MacLaren was active at the National Film Board (Canada) from the '40s to the late '80s, I think.
He made several films where his sound track was made either by painting on transparent sound track,
or scratching black sound track area, or actually photographing
strips of board with black lines on it, and then putting that image on the sound track.
(No wonder he wound up sniffing glue.)
If MacLaren is new to you,
Check out: http://www.nfb.ca/explore-by/director/Norman-McLaren/
(Especially "Neighbours")
and
http://www.youtube.com/watch?v=E3-vsKwQ0Cg
"Dots", which was made in 1940.
There is also a long form doc on MacLaren's life and work.
- Hope that you might find some of this interesting/helpful. (except maybe the glue part)
One more week 'til the days start getting shorter and is still, around here, it goes up only to about 21C/70F.
Nuts!
JP
>
> In any case your point is well taken: that for printing or transfer
>
> the light can be adjusted accordingly.
>
> To my naked eye the dimming of this stock base does not look totally
>
> unusable for projection as well, maybe for certain instances. How bad
>
> could it be? Just a bit dimmer....
>
> Theoretically, not that it impacts the visual area of the frame, one
>
> could chemically remove the already exposed and process track area,
>
> at least for B&W. (eg. using the chemistry you mentioned in your
>
> earlier post).
>
> Color film track neg, of course, has the same orange backing as the
>
> regular color neg film stock, is it also dimmed down in the base?
>
> Hadn't ever noticed that.
>
>
>
> Myron
>
>
>
>
>
> On Jun 12, 2009, at 3:55 AM, JEFFREY PAULL wrote:
>
>
>
> > Hi, Myron,
>
> >
>
> > On Thu 11/06/09 16:22 , Myron Ort email suppressed
> sent:
> >> We talked of the chemistry doing this for b&w film,
> but what will
> >> remove opacity from a color print without removing the
> emulsion?
> >> Any info on this one?
>
> >>
>
> >> Unreel the film over the entire backyard or roof, and
> let the sun
> >> hit it all summer.
>
> >
>
> > No, actually, I don't know of anything, which explains
> that
> > particular silence in my text.
>
> >
>
> > - Jeffrey P.
>
> >
>
> >
>
> >
>
> > None of the following helps, but . . .
>
> > I remember there were chemicals you could use (or buy)
> that
> > lightened a colour film's individual dye layers to
> colour-shift,
> > or lighten underexposed slides. I think they turned the
> colour dyes
> > into their leuco variations which were colourless.
>
> > and if I remember correctly, this is what's happening
> when dyes
> > fade in the usual way.
>
> > These chemicals may have only worked on Kodachrome film
> which has a
> > different dye structure from all others.
>
> >
>
> > Until colour film really took over in the '60s,
> photography had
> > been enhanced by the ongoing labours of amateur
> darkroom workers
> > everywhere,
>
> > and hundreds of small companies making cheap
> specialized gear and
> > packaged chemicals.
>
> > These photo proto-nerds put tiny ads in, and published
> their
> > discoveries in the magazines of the era, and they knew
> their
> > chemistry and how to manipulate molecules.
>
> > Gone.
>
> > And now most of that photo infrastructure is gone, and
> access to
> > that information is also gone.
>
> >
>
> > Knowing that almost all film has been colour film for a
> long time now,
> > and that's just about all there is to begin a project
> with, I'll
> > keep cooking on it.
>
> >
>
> > A guy named Patrick Dignan published a lot of this sort
> of stuff,
> > see if Google helps give you leads.
>
> >
>
> > But probably the only feasable thing to do nowadays is
> buy so-
> > called "lightstruck" leader,
>
> > or B&W print stock - even from a lab that's still doing
> B&W - and
> > dunk it directly in photo fixer to remove the silver
> halides
> > and wind up with transparent film with gelatine coating
> intact.
> > B&W soundtrack stock works too, but it usually has a
> grey plastic
> > base which holds back some of the light.
>
> > This makes direct projection of original dimmer, but if
> you're
> > using it as original to be printed,
>
> > the lab can use a different light to compensate.
>
> >
>
> >
>
> >>
>
> >
>
> >
>
> >
> __________________________________________________________________
> > For info on FrameWorks, contact Pip Chodorov at (address suppressed)
> om>.
> >
>
>
>
>
>
> __________________________________________________________________
>
> For info on FrameWorks, contact Pip Chodorov at (address suppressed)
> om>.
>
>
>
>
>
__________________________________________________________________
For info on FrameWorks, contact Pip Chodorov at <email suppressed>.