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Old January 24th 04, 04:57 AM
Jean-David Beyer
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Default Road ruts with Jobo

Michael Scarpitti wrote:
Brian Kosoff wrote in message ...

Hi,

I'm using a Jobo cpp-2 processor I am getting an uneveness in
development which jobo refers to as "road ruts" that is a linear uneveness
that runs the long length of the film, in the direction of the rotation.
It's dense on the edge, then lighter 1/3 of the way in, then denser, then
lighter then denser.
Jobo says to slow the speed of the rotation down from the 75 rpm that
the manual suggests, so I have slowed it to about 50rpm, but I am still
getting the ruts. My film is 120 tmax 100, the developer is d-76 1:1, I
am using a 5 minute presoak, 4 rinses after fix and kodak rapid fixer. No
stop bath. I shoot primarily very high key scenes and still lifes where
eveness of background is critical.

Any help with this problem would be greatly appreciated, thanks.

Brian Kosoff
kosoff.com





Mechanical agitation that is invarying inevitably will be harder to
control than manual agitation using inversion in a standard tank. The
allure of mechanization is obvious, but I process exclusively by hand,
and never have uneven development.


I used to develop 4x5 sheet film in Calumet stainless steel 1/2 gallon
tanks in Kodak Stainless Steel hangers. During testing, I made uniform
exposures to entire sheets and measured the densities across the films
using my MacBeth TD-901 transmission densitometer. They were quite uniform.

When I switched to the Jobo CPE-2 processor with the old reels (I forget
their number), I had terrible uniformity problems. A broad denser stripe
down the middle of the film parallel to the 5" edge was quite obvious:
no densitometer was required. At the time Jobo suggested developping
only 4 sheets in each 6-sheet reel, leaving more space between the
negatives (or transparancies). Well that helped a lot, but even so, it
was not entirely satisfactory.

They redesigned the reels and now sell the 2509-N reels that work
perfectly. In addition the the redesign of the reels, the reels now come
with some plastic plates that are presumably to hold the films in place.
I never had trouble with films coming out even with the old reels, but
perhaps some people did. IMAO, thse retaining plates also greatly
improve the flow patterns, making (hypothetical) rushing between the
negatives less likely. So not stipes anymore. But this is old news,
since the "new" reels were probably introduced at least a decade ago by
now and I doubt anyone has the old type in stock.

In any case, I find my control over processing is much easier with the
Jobo processing than the manual processing I used to do. The
repeatability is certainly much greater that formerly, since the
agitation is always the same.

--
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