Re: Dumb question re: processing 4x5

On 2007-10-21, Richard Knoppow <dickburk@[EMAIL PROTECTED]
> wrote:
>
>      I also use Unicolor and Besler print drums for sheet 
> film. I have found that I can get "bromide streaks" on 
> occasion if the drums are rotated using the Unicolor motor 
> base unless they are taken off several times during 
> development and agitated sideways. Evidently there is not 
> enough turbulance in the flow of the developer to move the 
> reaction products away from the development sites in the 
> long direction of the drum. I've had this problem 
> specifically with Rodinal. Its likely it may not happen with 
> other developers but its worth beign aware of.
>      The streaks show up as lines of lighter density on 
> either side of dense highlights on the negative in the 
> direction of rotation.
>
I use the Jobo 2509N reels in 2500 series tanks for 4x5.
These do not get streaking (at least, not as measured on my
densitometer or by eyeball). But these were specifically designed
for developping sheet film, and are not paper drums being pressed
into service for film.

Also, the 2509N reels and drum were redesigned from an older set
of reels and drums that did streak (parallel with the 5" side
but near the middle. It took Jobo a second try before they worked
out well. So it is not easy.

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