What to do with Base + (plus) Fog

I'm shooting PX-125. Using the density function of my scanner I measure the
base on clear piece of developed film to be about .42 density units. So at
0.15 d.u.'s per half stop that's nearly a stop-and-a-half loss for base +
fog. Is that too much? What's base + fog costing me in terms of image
quality or is it treated as neutral density when I print?

What you really need to know, is how much is base density, and how
much is fog.
Do the same experiment again, cut the film in half, and normally
develop half, and just fix the other half. Then compare the density's.
My money says most of the density you see is film base assuming you
have 35mm. The thin base of 120 film has a lower density.

The film base is treated as neutral density, the fog encroaches on the
toe of the film, and if extensive will alter the shape of the d-log e
(density vs exposure) curve, from what is designed, and muddy up the
image. A low amount of fog can be treated as neutral density.
When in doubt, print it.
Adams defines zone 1 as .1 above film base+fog.
Dan

On Tue, 28 Dec 2004 16:40:40 GMT, "Hugh Jass"
wrote:

I'm shooting PX-125. Using the density function of my scanner I measure the
base on clear piece of developed film to be about .42 density units. So at
0.15 d.u.'s per half stop that's nearly a stop-and-a-half loss for base +
fog. Is that too much? What's base + fog costing me in terms of image
quality or is it treated as neutral density when I print?

Thx Dan. Thanks I will try running a strip developed and fixed and then one
just fixed and see what the difference is. My development was ~5:36 seconds
(7 minutes - 20 per cent = 5:36) in Ilfosol-S at 1:9. I minus the 20 per
cent because I'm printing on a condensor head.

"Dan Dunphy" wrote in message
...
What you really need to know, is how much is base density, and how
much is fog.
Do the same experiment again, cut the film in half, and normally
develop half, and just fix the other half. Then compare the density's.
My money says most of the density you see is film base assuming you
have 35mm. The thin base of 120 film has a lower density.

The film base is treated as neutral density, the fog encroaches on the
toe of the film, and if extensive will alter the shape of the d-log e
(density vs exposure) curve, from what is designed, and muddy up the
image. A low amount of fog can be treated as neutral density.
When in doubt, print it.
Adams defines zone 1 as .1 above film base+fog.
Dan

On Tue, 28 Dec 2004 16:40:40 GMT, "Hugh Jass"
wrote:

I'm shooting PX-125. Using the density function of my scanner I measure
the
base on clear piece of developed film to be about .42 density units. So
at
0.15 d.u.'s per half stop that's nearly a stop-and-a-half loss for base +
fog. Is that too much? What's base + fog costing me in terms of image
quality or is it treated as neutral density when I print?

In article c0gAd.582822$Pl.122249@pd7tw1no,
"Hugh Jass" wrote:

I'm shooting PX-125. Using the density function of my scanner I measure the
base on clear piece of developed film to be about .42 density units. So at
0.15 d.u.'s per half stop that's nearly a stop-and-a-half loss for base +
fog. Is that too much? What's base + fog costing me in terms of image
quality or is it treated as neutral density when I print?

Its rather difficult to comment. Why, you ask? Well,....

Is it sheet film or roll?

The density function of your scanner and its "accuracy" is an unknown.
Its not standard photo sensitometeric nomenclature, nor can it be
without very precise specific guidelines to determine its calibration
values.

--
LF Website @ http://members.verizon.net/~gregoryblank

"To announce that there must be no criticism of the President,
or that we are to stand by the President, right or wrong,
is not only unpatriotic and servile, but is morally treasonable
to the American public."--Theodore Roosevelt, May 7, 1918

Gregory Blank wrote:

In article c0gAd.582822$Pl.122249@pd7tw1no,
"Hugh Jass" wrote:



I'm shooting PX-125. Using the density function of my scanner I measure the
base on clear piece of developed film to be about .42 density units. So at
0.15 d.u.'s per half stop that's nearly a stop-and-a-half loss for base +
fog. Is that too much? What's base + fog costing me in terms of image
quality or is it treated as neutral density when I print?


Just dunk a piece of leader in full strength Clorox to remove the
emulsion. What remains will be the base density which is a dye in the
plastic, not a coating on 35 mm. Ilford HP5+ has a base density of about
0.2. I think most Kodak films are clearer. The purpose of the base
density in 35 mm film is mostly to prevent light piping through the film
from frame to frame. If the base were perfectly transparent, exposure of
one end would send light all the way to the othe end, even though it is
in a light tight cartridge. The film could have an opaque undercoating.
but why bother when a base density of 0.1 will do the job?

"Hugh Jass" wrote in message
news:c0gAd.582822$Pl.122249@pd7tw1no...
I'm shooting PX-125. Using the density function of my
scanner I measure the
base on clear piece of developed film to be about .42
density units. So at
0.15 d.u.'s per half stop that's nearly a stop-and-a-half
loss for base +
fog. Is that too much? What's base + fog costing me in
terms of image
quality or is it treated as neutral density when I print?

Have you any means of calibrating the scanner?
Photographic density is usually stated as Log density where
density is the reciprocal of transmission. Typical roll and
sheet film bases are very clear. 35mm B&W negative film is
usually coated on a base containing a gray pigment with
density of around 0.2. This has no effect on tonal rendition
but extends printing exposure a little.
Fog is usually uniform and has the effect of lowering
the toe contrast which is equivalent to lowering speed. The
use of an anti-foggant in the developer will result in
eliminating the fog but also lowers speed so there is not
much net gain. Increasing exposure will generally overcome
the fog. If you want to use an anti-foggant Benzotriazole is
more effective than Bromide and has less effect on the
latent image (i.e., does not lower speed so much).
All film has some fog even when fresh, but slow films,
like Plus-X Pan, have very little.
The ideal method of calibrating the scanner is by using
a step wedge like the Stauffer wedge. However even a neutral
density filter of known density can be used. This will tell
you if the "density units" of the scanner have any relation
to the normally used Log density.


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

In article , PATRICK GAINER
wrote:

Just dunk a piece of leader in full strength Clorox to remove the
emulsion. What remains will be the base density which is a dye in the
plastic, not a coating on 35 mm. Ilford HP5+ has a base density of about
0.2. I think most Kodak films are clearer. The purpose of the base
density in 35 mm film is mostly to prevent light piping through the film
from frame to frame. If the base were perfectly transparent, exposure of
one end would send light all the way to the othe end, even though it is
in a light tight cartridge. The film could have an opaque undercoating.
but why bother when a base density of 0.1 will do the job?

Patrick;

Is there a relatively simple way to extract the silver from emulsion
and reuse it as emulsion again for something like albumen printing.
Any thoughts?

Greg



--
LF Website @ http://members.verizon.net/~gregoryblank

"To announce that there must be no criticism of the President,
or that we are to stand by the President, right or wrong,
is not only unpatriotic and servile, but is morally treasonable
to the American public."--Theodore Roosevelt, May 7, 1918

"Richard Knoppow" wrote in message
...

"Hugh Jass" wrote in message
news:c0gAd.582822$Pl.122249@pd7tw1no...
I'm shooting PX-125. Using the density function of my
scanner I measure the
base on clear piece of developed film to be about .42
density units. So at
0.15 d.u.'s per half stop that's nearly a stop-and-a-half
loss for base +
fog. Is that too much? What's base + fog costing me in
terms of image
quality or is it treated as neutral density when I print?

Have you any means of calibrating the scanner?
Photographic density is usually stated as Log density where
density is the reciprocal of transmission. Typical roll and
sheet film bases are very clear. 35mm B&W negative film is
usually coated on a base containing a gray pigment with
density of around 0.2. This has no effect on tonal rendition
but extends printing exposure a little.
Fog is usually uniform and has the effect of lowering
the toe contrast which is equivalent to lowering speed. The
use of an anti-foggant in the developer will result in
eliminating the fog but also lowers speed so there is not
much net gain. Increasing exposure will generally overcome
the fog. If you want to use an anti-foggant Benzotriazole is
more effective than Bromide and has less effect on the
latent image (i.e., does not lower speed so much).
All film has some fog even when fresh, but slow films,
like Plus-X Pan, have very little.
The ideal method of calibrating the scanner is by using
a step wedge like the Stauffer wedge. However even a neutral
density filter of known density can be used. This will tell
you if the "density units" of the scanner have any relation
to the normally used Log density.

Thx Richard. I'm currently waiting for two T2115s and two R1215s from
Stouffer which I order last week. Currently, the only thing I'm comparing to
is the grey-scale on a Q-60 card from Wolf Faust. The scanner (Epson 3200)
is surprising accurate to that, but it's not transmissive. The densitometer
function is from VueScan which uses data from the RAW file instead of
"corrected" data -- so while not exact it is ball park I'm guessing. The
film is 35mm, but was a hand me down from a retired photog' who'd had it in
the freezer. I rate at 100 and generally try to give the shadows a chance.
The neg looks dark or darker in comparison than what I usually shoot on,
TMY. I've used both D-76 and Ilfosol-S and am less than happy with my
results. I get strange posterization in places where I don't think there
should be any (in the mids) and the shadows look a bit muddy. Maybe it's
just old film. Maybe it just that I'm not use to Plus X. I'll keep
tinkering, and dig out my ND filters...good tip.

Hugh Jass wrote:
"Richard Knoppow" wrote in message
...

"Hugh Jass" wrote in message
news:c0gAd.582822$Pl.122249@pd7tw1no...
I'm shooting PX-125. Using the density function of my
scanner I measure the
base on clear piece of developed film to be about .42
density units. So at
0.15 d.u.'s per half stop that's nearly a stop-and-a-half
loss for base +
fog. Is that too much? What's base + fog costing me in
terms of image
quality or is it treated as neutral density when I print?

Have you any means of calibrating the scanner?
Photographic density is usually stated as Log density where
density is the reciprocal of transmission. Typical roll and
sheet film bases are very clear. 35mm B&W negative film is
usually coated on a base containing a gray pigment with
density of around 0.2. This has no effect on tonal rendition
but extends printing exposure a little.
Fog is usually uniform and has the effect of lowering
the toe contrast which is equivalent to lowering speed. The
use of an anti-foggant in the developer will result in
eliminating the fog but also lowers speed so there is not
much net gain. Increasing exposure will generally overcome
the fog. If you want to use an anti-foggant Benzotriazole is
more effective than Bromide and has less effect on the
latent image (i.e., does not lower speed so much).
All film has some fog even when fresh, but slow films,
like Plus-X Pan, have very little.
The ideal method of calibrating the scanner is by using
a step wedge like the Stauffer wedge. However even a neutral
density filter of known density can be used. This will tell
you if the "density units" of the scanner have any relation
to the normally used Log density.

Thx Richard. I'm currently waiting for two T2115s and two R1215s from
Stouffer which I order last week. Currently, the only thing I'm
comparing to
is the grey-scale on a Q-60 card from Wolf Faust. The scanner (Epson
3200)
is surprising accurate to that, but it's not transmissive. The
densitometer
function is from VueScan which uses data from the RAW file instead of
"corrected" data -- so while not exact it is ball park I'm guessing.
The
film is 35mm, but was a hand me down from a retired photog' who'd had
it in
the freezer. I rate at 100 and generally try to give the shadows a
chance.
The neg looks dark or darker in comparison than what I usually shoot
on,
TMY. I've used both D-76 and Ilfosol-S and am less than happy with my
results. I get strange posterization in places where I don't think
there
should be any (in the mids) and the shadows look a bit muddy. Maybe
it's
just old film. Maybe it just that I'm not use to Plus X. I'll keep
tinkering, and dig out my ND filters...good tip.

Do you see the strange effects on the negatives directly or on the
scanned image?
D-76 should give you good tonal rendition. I've not used Ilfosol-S
but it should also be good. Its a Phenidone/Hydroquinone/Ascorbic acid
developer.
If the negatives appear to have blotchy fog it may be due to some
damage it suffered while refrigerated.
Plus-X roll and 35mm film is a good general purpose film. It should
be giving you good results without any special fuss.
What is your developing routine? If you get good results with T-Max
you should not be having trouble with Plus-X
Richard Knoppow
Los Angeles, CA, USA

An easy way used by those who do darkroom work is to
soak the silver containing emulsion in a thiosulfate solution.
The thiosulfate will dissolve the silver. May be you know
of that.

After treatment of that solution will depend upon your
end usage. The form of silver needed for albumen prints,
whatever that may be, is likely an easy
conversion process. Dan