[rollei_list] Re: Tri-X developer
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <rollei_list@xxxxxxxxxxxxx>
- Date: Fri, 23 May 2008 19:56:12 -0700
----- Original Message -----
From: "Marc James Small" <marcsmall@xxxxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>; <rollei_list@xxxxxxxxxxxxx>
Sent: Friday, May 23, 2008 4:31 PM
Subject: [rollei_list] Re: Tri-X developer
I think you misinterpret my opinion of Rodinal. It is a
very convenient and very reliable developer and will develop
virtually any film satisfactorily. Its also a good paper
developer albeit a bit expensive for that. I've found it to
give good tone rendition with all films I've used it for.
I've mainly used Rodinal for sheet film although I've tried
it for 120 and 35mm. It is relatively free of developer fog
and dichroic fog. This last can be a problem for some film
and developer combinations.
The main shortcoming of Rodinal is grain but that
depends on its dilution and the nature of the film. For
inherently fine grain films Rodinal does pretty well. For
coarser grained ones the grain may be excessive in
comparison with developers with inherently finer grain.
There IS some loss of speed with Rodinal but its in
about the same class as other developers with bromide in
them such as DK-50, etc. Not a major loss. It is not a good
pushing developer although some claim that. The main
requirement for a pushing developer is that it can increase
speed without increasing contrast. This is mostly a property
of Phenidone developers. It also must not produce fog as
development is extended. In this respect Rodinal does quite
well. At some point all developers will begin to increase
fog density faster than image density.
Rodinal is relatively high in pH which can cause
softening of the emulsion in some films with attendent grain
clumping. It is also rather low in salt content which also
tends to favor swelling. Overall salt content is more
important in this respect than sulfite alone. Rodinal has
sulfite in it although a relatively low amount compared to
D-76 and similar developers. Sulfite does tend toward fine
grain for several reasons of which being a halide solvent is
only one.
Since some modern films have very hard emulsions (T-Max
of all types for example) the effect of the high pH on grain
clumping is minimal with them.
HC-110 is another interesting developer. It is also
very convenient and reliable. It can be used for most films
but, like Rodinal, is not optimum. I think the reason Ansel
Adams liked it was because its activity can be varied easily
by dilution giving a wide range of possible contrast in
development without having to work at very short or long
times.
The characteristic curves of several films which
compare HC-110 to other developers show that it can produce
some shouldering off on highlights. Some may consider this
desirable but low contrast is not the same thing as having
detail, in fact its the opposite.
Nonetheless, if you are stuck with only one developer
for a range of work Rodinal or HC-110 is a good choice. I've
never tried HC-110 for print developing but Rodinal at about
1:25 is actually a very good print developer.
HC-110 is very interesting to photographic chemists
because it is remarkable for its concentration and the use
of some unusual compounds to take the place of the sulfite
and to maintain the whole thing in solution.
BTW one can mix something closer to an optimum version
of D-76 by reducing the amount of sulfite to 80 grams/liter
and using the buffered form. This has 8 grams of Borax
(granular) and 8 grams of Boric Acid (crystals) per liter.
The activity can be adjusted by varying the ratio of Borax
to Boric acid. With equal amounts as above the activity will
be the same as fresh mixed standard D-76. The advantage is
that the activity will not change with time.
Also, D-76, when fresh, has a slight tendency to fog.
This can be eliminated by adding about 0.25 gram/liter of
potassium bromide to it. This suppresses the slight fog and
produces a very slight increase in effective film speed. If
you use replenished D-76 enough bromide will accumulate from
the film to preclude the need for adding any although the
small amount above will act as a sort of "ripener" for it
reducing the change in activity from fresh to equalibrium
state.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
---
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