What happens to neg quality as dev becomes exhausted?

I want to shoot some resolution shots to test my LF lenses. If I use
D-76 that has been spent developing other negatives, what can I expect
from the negatives developed beyond the rated capacity? The qualities
in a negative that the developer impacts are contrast, maximum density
and accutance (maybe more?). I am guessing that as developer action
declines, max density suffers, and therfore contrast. Could more
frequent agitation or increased temperature help this? The point is
avoid creating more water pollution for negatives that will never be
printed, but if using old developer makes it impossible to judge the
quality of the image, then it will not serve as a good indication of
lens quality. Also, what is the dark precipitate seen in used developer
that has sat for a while?

Thanks,

Scott

You don't say how you are performing these tests but accutance can affect
the perceived sharpness of the results. I know we're all doing our part to
help the environment on a micro-scale but the effort expended on lens tests
would require me to suggest you use fresh developer for each test for more
repeatable results. Note that most developer components fall into the
categories of harmless or bio-degradable, most of the concern today is about
silver compounds. Most darkroom chemical makers will concur that the amount
of effluent that a home darkroom discharges will never harm even a
micro-ecosystem like a septic system much less a municipal sewage system.

Having said that, and with no desire to spark another long thread on
environmental issues, I must also say that the possibility is quite good
that some, pencil-necked, paper pusher in a city office would have a field
day if you actually tried to be a good guy and comply with all the regs (not
to mention the fact that you'd go broke).

When I saw the local lead acid battery rebuilder washing down his shop
floors into the local storm sewer and drive by the local packing plant daily
gagging and puking because of the smell, drive by the local metal plating
plant wondering what they are putting into the air and ground water and
observe the soot and crap coming out of the local coal fired power plants I
gave up on micro-ecology and decided to wait until local government reins in
the big boys. The difference of course is jobs and "the economy" local
government will do nothing to stop large scale pollution since it might
upset the local job market.

In the meantime I know that my hobby darkroom (20 to 100 rolls of film per
month--hey even I get busy once in a while) is doing very little to harm the
environment. Kodak, Ilford and everyone else that went on record on this
issue has said so. Even so, I'm a careful worker and frugal in my use of
darkroom materials and am careful about what I put down the drain.

--
darkroommike
"tbrown" wrote in message
oups.com...
I want to shoot some resolution shots to test my LF lenses. If I use
D-76 that has been spent developing other negatives, what can I expect
from the negatives developed beyond the rated capacity? The qualities
in a negative that the developer impacts are contrast, maximum density
and accutance (maybe more?). I am guessing that as developer action
declines, max density suffers, and therfore contrast. Could more
frequent agitation or increased temperature help this? The point is
avoid creating more water pollution for negatives that will never be
printed, but if using old developer makes it impossible to judge the
quality of the image, then it will not serve as a good indication of
lens quality. Also, what is the dark precipitate seen in used developer
that has sat for a while?

Thanks,

Scott

In article .com,
says...
I want to shoot some resolution shots to test my LF lenses. If I use
D-76 that has been spent developing other negatives, what can I expect
from the negatives developed beyond the rated capacity? The qualities
in a negative that the developer impacts are contrast, maximum density
and accutance (maybe more?). I am guessing that as developer action
declines, max density suffers, and therfore contrast. Could more
frequent agitation or increased temperature help this? The point is
avoid creating more water pollution for negatives that will never be
printed, but if using old developer makes it impossible to judge the
quality of the image, then it will not serve as a good indication of
lens quality. Also, what is the dark precipitate seen in used developer
that has sat for a while?

Thanks,

Scott


Generally as developer get used it has less active ingredients so it
takes longer to develop to the same contrast. There may also be some
effect from the oxidized developer by products left from previous uses.

Kodak used to give times for reuse of D76 without replenishment, perhaps
you can find them someplace. The problem is one doesn't really know how
much to increase the developing time with each use. Partly it depends on
how dense the prior films were.

If you want to conserve water want not replenish the developer. You can
buy D76R or mix it yourself. Another approach is to use a standard
developer like D76 diluted as a one shot. This way you always have fresh
developer for each batch.

Black stuff floating in developer is dissolved silver caused by the
silver solvent added to the formula to promote fine grain. It does no
harm, but can leave spots so it should be filtered out. If you have a
lot you should be using fresh developer.

Why spoil all your hard work and expensive film over a few cents worth
of developer?
--
Robert D Feinman
Landscapes, Cityscapes and Panoramic Photographs
http://robertdfeinman.com
mail:

"Robert Feinman" wrote in message
...
In article
.com,
says...
I want to shoot some resolution shots to test my LF
lenses. If I use
D-76 that has been spent developing other negatives, what
can I expect
from the negatives developed beyond the rated capacity?
The qualities
in a negative that the developer impacts are contrast,
maximum density
and accutance (maybe more?). I am guessing that as
developer action
declines, max density suffers, and therfore contrast.
Could more
frequent agitation or increased temperature help this?
The point is
avoid creating more water pollution for negatives that
will never be
printed, but if using old developer makes it impossible
to judge the
quality of the image, then it will not serve as a good
indication of
lens quality. Also, what is the dark precipitate seen in
used developer
that has sat for a while?

Thanks,

Scott


Generally as developer get used it has less active
ingredients so it
takes longer to develop to the same contrast. There may
also be some
effect from the oxidized developer by products left from
previous uses.

Kodak used to give times for reuse of D76 without
replenishment, perhaps
you can find them someplace. The problem is one doesn't
really know how
much to increase the developing time with each use. Partly
it depends on
how dense the prior films were.

If you want to conserve water want not replenish the
developer. You can
buy D76R or mix it yourself. Another approach is to use a
standard
developer like D76 diluted as a one shot. This way you
always have fresh
developer for each batch.

Black stuff floating in developer is dissolved silver
caused by the
silver solvent added to the formula to promote fine grain.
It does no
harm, but can leave spots so it should be filtered out. If
you have a
lot you should be using fresh developer.

Why spoil all your hard work and expensive film over a few
cents worth
of developer?
--
Robert D Feinman
Landscapes, Cityscapes and Panoramic Photographs
http://robertdfeinman.com
mail:

The effects of use are more complex than this. When
processing reaction products of development and some ions
from the halide are left in the developer. The most
important reaction product is probably bromide. Bromide acts
as a restrainer, especially for silver halide crystals that
have received low exposure. The result is some loss in
shadow detail even when development time is incresed to
achieve a constant contrast. The effect may be more
noticable in D-76 than some other developers because D-76
contains no bromide where many other developers do for
because they need the fog suppression. D-76 tends to be long
lived because the two developing agents, Metol and
Hydroquinone, tend to regenerate each other.
D-76, and many other developers, can be kept going for
very long periods of time by adding a replenisher. Kodak
sells a packaged replenisher for D-76 as D-76R. A small
amount is added for each film developed. Ideally, some
method of testing for consistent development should be done,
but even just keeping the volume up will stretch the
developer life.
The advantage of a replenisher is that contrast will
remain essentially constant once the developer reaches
equilibrium. However, the accumulated bromide will still
reduce shadow detail somewhat. D-76, in one variation or
another, was the standard developer for motion picture B&W
negative processing for many years. It was used in automatic
machines with automatic replenishment. Even the current
developer recommended by Kodak for this application is
really a variation of D-76.
The black precipitate may be dissolved halide which has
become metallic silver due to exposure to light, or it may
be particles of gelatin from the emulsion. Sometimes this is
also caused by micro-organisms growing in the developer.
Filtering will help but I agree with those who think
developer is cheap compared to film and to the cost of lost
pictures. Dump it.


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