Re: [Leica] Re: RE: film tape glue flash

["Mary and Stan Kephart" <kephartol@att.net>]

Jim,

I concede.  I just looked at those negs and the "fogging" looks more like
the result of light leak.  Gotta get around fixing those leaks!

Thanks for setting me straight.

MJK

- --Love is kind.


- ----------
>From: Jim Brick <jim_brick@agilent.com>
>To: leica-users@mejac.palo-alto.ca.us, leica-users@mejac.palo-alto.ca.us
>Subject: [Leica] Re:  RE:  film tape glue flash
>Date: Thu, May 31, 2001, 7:03 PM
>

> At 05:23 PM 5/31/01 -0400, Mary and Stan Kephart wrote:
>>Friends,
>>
>>Warning!  I messed up a roll of 120 film big time by ripping off film from
>>the reel.  Lots of fog, maybe because of the longer strip?
>>
>>MJK
>>
>>--Love is kind.
>
>
> Mary,
>
> Sorry to have to dispel your theory... I'll answer your LF questions soon...
:)
>
> For 40 years I have been ripping off 120 tape. I even pride myself in the
> ability to produce a really big flash. But big is relative. The amount of
> light, and its wavelength, will do nothing to your film except "perhaps"
> directly under the tape itself. That is, the film that is stuck to the
> tape. That's even debatable as there is a layer of glue still there.
>
> When you pull the tape off of the film (or paper backing) the rest of the
> roll is either curled up or loaded onto a reel, depending upon how you do
> it. The point being, the film is not laid out flat with emulsion pointing
> directly at the tape that you are about to rip off. And even if it were,
> the amount of light generated is exceedingly minuscule. Film reciprocity
> effects make it useless light. This light has no ability to penetrate
> anything. Certainly not through layers of anti-halo and backing and
> emulsion, and not even the silver halide molecules in the emulsion if it
> were laying right there.
>
> As I said, been ripping the stuff for years, even trying to out flash
> yesterday's flash. Many years ago, Kodak 120 film tape was spectacular. But
> the flash has no brilliance, is "cold" light (electroluminescence) and has
> no ability to fog film.
>
> I have "cold" light luminous tape all over my darkroom that is much much
> brighter than the very short lived "cold" light flash. The reciprocity
> characteristics of film dictate that a giant number of concurrent (or
> consecutive) flashes would have to happen to be even barely detectable (if
> at all) on most films. Easier on super sensitized astro film than ordinary
> camera roll film.
>
> Folks, this is not a problem. If you have a roll of fogged film, IT IS NOT
> from the minuscule film/paper glue flash. If it were, don't you think that
> this would have been an issue with Kodak over the past 40+ years. And Fuji,
> Agfa, etc...
>
> But it isn't.
>
> Every lab in the world rips off the tape, in the dark, many with previous
> rolls hanging right there, emulsion out, a few inches away, waiting to go
> into the dip & dunk processor. I used to be part owner of a lab. Done this
> thousands of times. Lots of flashes. No fog.
>
> Jim