Film Development tubes and Negative Streaking


Stephen Harrison (SH@stephenharrison.com)
Sat, 20 Mar 1999 14:47:41 -0800


Carl, ,
>
>Are the tubes you are using completely smooth inside? If so, I'm back to
>square one understanding the streaks. I thought they came from the
>ridges in the print drums I was using. My hunch is that your reversing
>modification may help a lot. I'll have to ask Jon about this machine, I
>don't think it's mentioned in the literature I have on his products.
>
You are right, It is not mentioned but I love the unit and I use it daily.
Yes, my film tubes are smooth PVC tubes. I can spin them at varying rpm
speeds. After the film is loaded I invert the tube thus releasing the
developer from the cap below and shake vigorously for 20 to 30 seconds.
Thus the agitation for the first 30 seconds is not rotary but random and
chaotic. I use straight D-76 s made from distilled water so minerals in the
water is not the problem. As mentioned,tThe bromide drag is very subtle
with the 7x17 inch tubes but is definately present and seems to be a sort
of wake after areas of increased density such as if the silver halide is
dragged from an opaque mountain top onto the sky. I do not believe the
reversing swith is going to cure it also. It is interesting that my 5x7
film tubes which spin very fast at at least 120 rpm do not show any
streaking at all in any area. Perhaps the revolution per minute is
significant here and the developer drag less significant across the surface
of the film. The edges of my film show no streaking.
         I love the rotary development because of the large number of
sheets I am able to do at one time ( up to 10 sheets of 7x17 at a time) and
the fact that my hands arent't dripping in chemistry for 30 minute periods
of time.It is so convenient and pleasant and the temp is electronically
controlled which is a big advantage.

>BTW, going back to old fashioned trays does not (as you'll see in Pat
>Alt's message) mean a sentence of one sheet at a time. Batch development
>works great as long as you get the scratch situation under control

But it is difficult to do using the BTZS system where each sheet of film is
developed for different time periods. I like the capability of having
different development times.

Stephen Harrison



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