N+ and N- times for Pyro

[mark_lipton]

I am currently developing 4x5 negatives of Tri-X Pro Pan (rated at 200) and Bergger Pan (rated at 100) in the Leban ABC Pyro formula in a Jobo Expert Drum. Normal development runs between 7-1/2 minutes and 8 minutes. I would appreciate any suggestions regarding N+ and N- times for these films. Thank you.

[fred8]

Mark

 

<p>

 

You say that you are using Tri-X Pro Pan by which I take it that you

are using the Tri-X nominally rated at 320 by Kodak. If this is the

case then, depending on the type of photography you do, there could

be some significant pitfalls. Unless this film has been redesigned

and reformulated it is recommended for studio use only, and if used

outdoors could offer some serious problems depending on the lighting

conditions. Most people buy the pro films because of the short dating

and and what is supposed to be optimum aging. The fact is that Tri-X

professional is designed for studio use in extremely controlled

lighting conditions, and it has no anti-halation backing. Used

outdoors on bright, or even cloudy bright days, there can be

significant light scattering in the emulsion which can impact your

controlled development and contrast methods. Having said that, I have

used the film for many years and like it a lot, but I do not consider

it to be the best film for many lighting conditions. There is also

the possibility that the film you are testing is different from what

was previously available to me. In that case you are on your own here

and I wish you the best of luck. I know absolutely nothing about

Bergger film, so I am an empty fountain of knowledge there. See if

you can get some Kodak Ektapan (ei 100) and try that out. I used this

film a lot and really liked it. Don't remember how I rated it because

I quit using light meters many years ago. Find a film/developer

combination you like (and I used D-23 split and loved it) and stay

with that.

[doremus_scudder1]

Mark,

 

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Don't concern yourself too much with the alluded to inflexibility of

Tri-X in 4x5 size. Ansel Adams and countless other photographers of

merit (myself modestly included) use(d) Tri-X Pro 4x5 outdoors,

(which, incidentally, is not the same film as Tri-X Pro in roll film

formats), with excellent results. If you understand your

film/developer characteristics, you can use it under just about any

lighting condition. Tri-X has proved itself to be a great "general-

purpose film" (to quote Kodak).

As to your original question, I can only say that the individuality

of approach and equipment combinations precludes any definitive

determination of N+ or N- times. You need to test for yourself. If

you don't have a densitometer (I don't either) I suggest you get a

copy of "The New Zone System Manual" by Minor White, Richard Zakia,

et al. and review their suggestions for Zone system calibration. I

have found this approach to be quite accurate, useful and quick once

you get the hang of it. Regareds, ;^D)

[bob_moulton]

Mark,

The preceding comment by Doremus Scudder is the best advice. Test for

N- and N+ yourself.Recall that you cannot easily use a densitometer

to interpret the results due to the staining.

However, some writers suggest that Tri-X and other films of its

type,meaning non T-Max or Delta, require for N+ a 30-40% increase in

normal film development time + plus a 1/2-1 stop decrease in

exposure. For N-1 the development time , the normal development time

should be reduced by 30-40%, and the exposure increased by one stop.

Gordon Hutchings suggests the following for Tri-X: (N=14 min),

(N+1=20 min.), (N-1=11 min). But that is assuning an E! of 260 AND

the use of his PMK developer.

Hope this helps.

Bob

[william_marderness1]

I have tested HP-5 plus for the zone system with D-23 and D-25. With

both developers, each change of 1 zone in development needed a 1/3

stop change in exposure: N-1 needs 1/3 stop more than N; N+1 needs

1/3 stop less than N. N-1 required a 15% reduction in developing

time, N-2 required a 30% reduction, and N+1 required a 60% increase.

You might use these (or Bob's) suggestions as a guide.