Processing
Metal vs. Plastic
Reels
Using
a color head for variable contrast filtration
Black &
White Film Developing
Metal
vs. Plastic
Reels
Stainless
steel reels
(and tanks) transfer heat more rapidly than plastic. That's another way
of saying they will warm up or cool down faster than plastic reels (or
tanks). For film processing, temperature stability is a better
characteristic
than fast temperature changes. So while plastic tanks and reels take
longer
to get to the "proper" temperature for processing, they also stay there
more reliably than stainless steel.
Stainless steel is NOT impervious to many photographic
chemicals. Specifically
bleach and bleach/fix used in most color processes will eat through 316
stainless steel. Granted it won't happen overnight, but most commercial
processors today are made with PVC plastic tanks rather than stainless
steel for this very reason.
Most stainless steel reels, if dropped, generally become
useless. Once
the metal spirals become bent, it is virtually impossible to bend them
back to their original position. Plastic reels, if made with the right
materials, will withstand the impact of dropping (not throwing) and the
spirals will "bounce" back to their original position. The result is
they
are less likely to be damaged by dropping, but they will still bend
when
our plastic would spring back.)
Loading either reel type becomes the source of many debates.
It is generally
conceded that loading stainless steel reels is somewhat more difficult
to master, especially for 120 film. But once mastered it is generally
possible
to load a stainless steel reel in about half the time of a plastic
"walk-in"
reel. Also since stainless steel reels are loaded from a clip or teeth
in the center of the reel, and then wound around the center, rather
than
sliding along the spirals as in plastic reels, they are less likely to
be affected by humidity than plastic "walk-in" reels.
Stainless steel reels cost substantially more than plastic
reels. You
can generally count on double or triple the price of plastic, when
purchasing
a quality stainless steel reel.
However, the actual processing characteristic differences are
probably
the most important factor to consider. There are virtually none. That's
right! Both plastic and stainless steel reels will result in high
quality
film processing. Neither one has a distinct qualitative
advantage.
Using
a color head for variable contrast filtration
In addition to printing color photos, one of the great
advantages of
a dichroic color head enlarger is the ability to dial in black and
white
variable contrast filtration, rather than place filters below the
enlarging
lens. Filters under the lens will reduce the effective sharpness of
your
image.
Simplistically, you could start with the assumption that white
light
is approximately a contrast grade of 2.5 and know that by dialing
increasing
amounts of magenta filtration you increase the contrast of your print.
Conversely, dialing increasing amounts of yellow filtration would
result
in a lower contrast print.
However, while you are dialing in either filtration, you are
changing
the effective speed of the paper, due primarily to the filter factor
which
reduces the amount of light reaching the paper. To overcome the filter
factors, enlarger manufacturers suggest that you dial in certain
amounts
of the "opposite" filter to maintain a relatively consistent light
output.
This is exactly how Variable Contrast (VC) heads work.
VC heads are principally just color heads with different cams
to control
the filters. As you increase the contrast filtration, the magenta
increases
and the yellow reduces, but the exposure remains constant. However,
with
VC heads you cannot print color images, since you do not have separate
control over the individual filters, which is essential for color
printing.
Black
&
White Film Developing
1. You need: film developing tank, thermometer, at least one
accurate
measuring cylinder, film developer, film fixer, two empty bottles,
scissors,
two clothes pins.
2. Optional items include stop bath, photo flo and accurate
timer (you
can manage with a watch or clock with second hand.) You also need a
totally
dark space to load the film into the tank.
3. In total darkness, load the film onto the reel, put this
inside the
tank body together with the centre column, and screw the lid on. Now
take
it into normal room lighting.
4. Make up the developer and fixer (usually 300ml per film) to
the manufacturer's
instructions. For convenience, choose a liquid developer which is
diluted
for one shot use. Instructions for saving and reusing solutions are
included
with your chemistry.
5. Stand the bottles containing these solutions in hot or iced
water
to raise or lower the temperature to that stated in the developer
instructions
(normally 68F.)
6. Pour the developer into the tank, and start timing. Tap the
tank
solidly to dislodge any air bubbles from the film surface. Agitation is
normally by using a waterproof lid and turning the tank upside down,
pausing
briefly and turning it back. Agitate just enough that the developer is
washed evenly across the film surface. Excessive agitation increases
graininess
of the the film.
7. Follow the developer instructions for time and agitation
and at the
end of the time pour the developer down the sink (or back into the
bottle
if it is to be reused.)
8. Pour in water at process temperature. Agitate a couple of
times,
then pour out and fill with more water, 3 or 4 times. (Stopbath,
agititate
for 1 minute, return to bottle.)
9. Pour in fixer. Agitate frequently for 4 minutes (rapid
fixer) or
8 minutes (sodium thiosulphite fixer.) For T-Max films increase times
by
half. Return fixer to bottle.
10. Wash in water roughly at process temperature. Either use
changes
of water at roughly 2 minute intervals for 20-30 minutes, or a slow
stream
of running water. Failure to throughly remove the fixer with a through
wash will shorten the life of the film.
11. Give a final rinse - 1 minute - in a dilute solution of a
photographic
wetting agent like photo flo.
12. Pull the film carefully from the reel and drag it between
2 fingers
to remove the excess water.
13. Then hang the film to dry.
Tips:
1. Before loading, trim the end of the film sticking out of
the casette
square, then make a small cut across each corner to round it.
2. Fixer can normally process at least 20 films per litre of
solution.
Put a label on the bottle and make a mark for each film you
process.
Back to photography tips main page.
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