Film Pre-Exposure?

Never argue with a zonehead. They don't realize how stupid they are.
They just go to their 'holy books' and quote Adams, chapter and verse.
What difference is there between zoneheads and religious zealots?
NONE.

What is the difference between Mike Scarpathetic, Hans Beckert, and a liar?

Nothing...

Alexis Neel wrote:
: (Michael Scarpitti) wrote in message This is folly. Nothing to be gained except ruined shadow contrast.
: There are better ways, such as compemsating devlopment, that will
: accomplish your goal better.

: Wrong, as usual.

:
: Quit listening to morons.

: Oh I have stopped listening to you a long time ago. Not that you had
: anything to say except for dribble, or how did you put it...oh yeah,
: dreck.

I think that dreck is the word I used to discribe scarpitti's photographs.
I personally think that he should put is dreck back online to show the world
that he is an incompatentSP? photographer.
--




Keep working millions on welfare depend on you
-------------------

"Jon" wrote
MS wrote
Never argue with a zonehead.

Good advice. Please don't.

(Michael Scarpitti) wrote

"...I have a book by an
emulsion scientist that explains in detail what can be done with
... a very low-level exposure to light used to offset reciprocity
failure, 'The Science of Photography' by Baines, revised by Bomback,
cotains an extensive discussion of this on pages 199-208.

That's something to keep in mind. Glad you reminded me of the areas
of the scene where in reciprocity failure can occure.
Important low light areas which are subject to R. failure are likely
the ones which benefit most from pre-exposure. That would be according
to Baines.
Those low light areas where light levels are above R. failure are
where pre-exposure has less effect. Dan

(Dan Quinn) wrote in message om...
(Michael Scarpitti) wrote

"...I have a book by an
emulsion scientist that explains in detail what can be done with
... a very low-level exposure to light used to offset reciprocity
failure, 'The Science of Photography' by Baines, revised by Bomback,
cotains an extensive discussion of this on pages 199-208.

That's something to keep in mind. Glad you reminded me of the areas
of the scene where in reciprocity failure can occure.
Important low light areas which are subject to R. failure are likely
the ones which benefit most from pre-exposure. That would be according
to Baines.
Those low light areas where light levels are above R. failure are
where pre-exposure has less effect. Dan

Latensification is POST-exposure.

dr bob wrote:

"Dan Quinn" wrote in message
om...
Is anybody using pre-exposure when takeing pictures? I know it
requires multiple exposure capability but can be done, at least
for one frame, in advance of the actual picture takeing.

I've been lazy up till now but think the added shadow density and
gain of a stop or two in EI might be worth the extra effort.

What about technique? Will a plastic bag over the lens and a three
or four stops down exposure do the job? Dan

Dan:

The technique works well in some circumstances when the shadow values are
really off the scale and your visualization indicates they would enhance the
final print. Such a scenario as a beach scene where the subject has greatly
shadowed areas compared to the brightly lit "other" side(s). I have metered
a little gray card I carry around in the ol' bag but almost any printed
medium can be used as middle gray. Rack the focus out and make the exposure
as you suggest (3 or 4 stops down) then expose the subject. Develop
"normally". I have used this on roll film where it is difficult to alter
development per frame.I do have a couple of prints made from negatives
produced with this technique and will send you one email (650x650) for
brevity if you wish.

Truly, dr bob.

The theory of pre-exposure is based on the fact that film has a
threshold exposure below which nothing is recorded. If that threshold is
supplied by non-image light, more of the image light will be recorded by
being added to the pre-exposure. This is a very old technique. I first
read of it in Principles of Optics by Hardy and Perrin, published in
1932. Yes, contrast is lowered, but the shadow threshold is reduced. The
loss of contrast is made up by slightly more than normal development.

Patrick Gainer wrote in message ...
dr bob wrote:

"Dan Quinn" wrote in message
om...
Is anybody using pre-exposure when takeing pictures? I know it
requires multiple exposure capability but can be done, at least
for one frame, in advance of the actual picture takeing.

I've been lazy up till now but think the added shadow density and
gain of a stop or two in EI might be worth the extra effort.

What about technique? Will a plastic bag over the lens and a three
or four stops down exposure do the job? Dan

Dan:

The technique works well in some circumstances when the shadow values are
really off the scale and your visualization indicates they would enhance the
final print. Such a scenario as a beach scene where the subject has greatly
shadowed areas compared to the brightly lit "other" side(s). I have metered
a little gray card I carry around in the ol' bag but almost any printed
medium can be used as middle gray. Rack the focus out and make the exposure
as you suggest (3 or 4 stops down) then expose the subject. Develop
"normally". I have used this on roll film where it is difficult to alter
development per frame.I do have a couple of prints made from negatives
produced with this technique and will send you one email (650x650) for
brevity if you wish.

Truly, dr bob.

The theory of pre-exposure is based on the fact that film has a
threshold exposure below which nothing is recorded. If that threshold is
supplied by non-image light, more of the image light will be recorded by
being added to the pre-exposure. This is a very old technique. I first
read of it in Principles of Optics by Hardy and Perrin, published in
1932. Yes, contrast is lowered, but the shadow threshold is reduced. The
loss of contrast is made up by slightly more than normal development.

Pat:

Post-exposure latensification is what I am talking about. It is/was
used to help offset latent image decay from very long exposures, e.g.,
astrophotography. I would never fog film according to the technique
you cite.

In the B&W movie days, some overall fog was often added to night
scenes, but not to provide more shadow detail, but simply to lighten
the image overall. It does NOT increase shadow detail one whit,
because it was done after the negative was developed, at the
duplication stage, I presume at the interpositive stage. It was done
this way so as not to endanger the original negative. If you watch
Universal horror films of the 30's and 40's, you can see it as a
slightly milky image in night scenes, especially in films such as 'The
Wolf Man' with Lon Chaney Jr. It was also used for 'day for night'
scenes, which were shot under normal daylight, but underexposed about
two stops or so. The idea was to flatten out the scene.

Dan:

I use pre-fog or pre-exposure, to increase the Exposure Index
and reduce the contrast of very slow microfilms.

Al Doyle




"Dan Quinn" wrote in message
om...
Is anybody using pre-exposure when takeing pictures? I know it
requires multiple exposure capability but can be done, at least
for one frame, in advance of the actual picture takeing.

I've been lazy up till now but think the added shadow density and
gain of a stop or two in EI might be worth the extra effort.

What about technique? Will a plastic bag over the lens and a three
or four stops down exposure do the job? Dan

"Al Doyle" wrote in message ...
Dan:

I use pre-fog or pre-exposure, to increase the Exposure Index
and reduce the contrast of very slow microfilms.

Al Doyle


But 'regular' films don't benefit from that!

On 10 May 2004 15:03:57 -0700, (Dan Quinn) wrote:

Is anybody using pre-exposure when takeing pictures? I know it
requires multiple exposure capability but can be done, at least
for one frame, in advance of the actual picture takeing.

I've been lazy up till now but think the added shadow density and
gain of a stop or two in EI might be worth the extra effort.

What about technique? Will a plastic bag over the lens and a three
or four stops down exposure do the job? Dan

Ansel Adams used a gray card.

'nuff said.

jim h


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