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Zone System Question

Shift In EI

Many posts have mentioned the change in EI as a film is
pulled then pushed. I wonder if that is a concern for any
practical purpose. Just how much might one expect in
the way of a shift when, say, one departs from N-2
for N+2 development?

I rather think the change less than a stop. How ever
much the shift in EI is that much shift constant across
a broad selection of films? Dan
 
I don't ever change from my tested EI. I do mark 120 and 4x5 film for N+1 or N-1 depending on the scene brightness range.

I know you can expose Tri-X 400 at 1600 or more, but I've never liked the results of trying to make a particular film be something it's not.

Mike
 

Paul

You're right, 35mm from a bycicle doesn't sound ideal for the Zone System.

Good luck!
 

Dan

A two-stop shift is not unusual from N-2 to N+2. I expose Tmax-400 at EI-100 for N-2 and EI 320 for N+2.
 

Really? Many famous photographs have undoubtedly been achieved with both pulling and pushing. Pushing a film and overdeveloping isn't exactly rocket science compared to pulling a film and underdeveloping.
 
I don't think pushing and pulling is any different than N+1 or N-1, but I don't have to reset my meter. I still haven't seen a photo, in person, I really like that has been pushed very far.

I have seen prints from fast film that I do like.


Mike
 

I beg to differ. N- to N+ does not affect the shadows but only the highlights. Pushing and pulling affects the shadows.
 
RalphLambrecht said:
I beg to differ. N- to N+ does not affect the shadows but only the highlights. Pushing and pulling affects the shadows.
Click to expand...

Right! A. A. was not concerned with film speed AFAIK. Developing more or less to suit the scene was for the purpose of making narrow range and wide range scenes fit on the same paper. One can think of pivoting the characteristic curve about the shadow exposure so as to make the highlight of the print be very near paper white when the significant shdow is very near maximum black. It does not obviate dodging or burning in those cases where there are two or more scenes in one photo, as for example in an indoor scene that includes a picture window. I'm old enough to be forgetful, but I cannot remember any time that he advised pushing the film speed to make the shadows denser so as to make a narrow range scene fit the paper.
 

You're right, it isn't any different. When you "push" film a stop you first underexpose it a stop. So Zone III drops down to Zone II and Zone VIII drops down to Zone VII. THEN you give it N+1 processing. So the shadow area that has dropped to Zone II stays there BUT the highlight that dropped down to Zone VII is expanded back up to Zone VIII. The negative now has the same density range as the normal negative. Therefore the negative will print with the same range of tones as a normally exposed negative given normal development using the same grade of paper. The same result can be achieved by just using a paper one grade higher instead of giving the N+1 development. In fact, that is the standard definition of paper grade (not that all papers work out that nicely). One grade change expands/contracts by one zone.

The take home message is that the shadow detail of what was in Zone III for a normally exposed negative (not "pushed") is lost forever once the film is underexposed and it drops down to Zone II. That may be why you are not fond of prints made from "pushed" negatives. The shadows can be dark and lacking detail where you feel you should be able to see some.

Henry
 
The thing with shadows is that I feel the human eye and mind has an easier time filling in the blanks when it comes to shadows as compared to highlights. Highlights, coupled with mid-tones, and upper shadows, tend to suggest the missing shadow detail.

You'll find a similar thing in music with regards to lower harmonics lacking and upper harmonics filling in the blanks or leading the ear as to what the lower harmonics should sound like. Engineers take advantage of this all the time in order to decrease the amount of signal used for lower dynamics but still have a full sounding mix. Light and sound aren't the same - but in a way we're dealing with putting down an analog source onto another (limited) analog medium.

It's for this reason, and what my eyes tell me, that I do not mind the lost shadow detail when pushing, honestly. For me, the subject and/or what's being said in the photograph is many times more important than so-called "fidelity."
 
Music? From my seat as principal oboist I heard it all. After that, Hi-Fi was pretty low. It still is not the same as real, but is good enough to remind me of those days with the Norfolk Symphony, which is now the Virginia Symphony.
 
gainer said:
Music? From my seat as principal oboist I heard it all. After that, Hi-Fi was pretty low. It still is not the same as real, but is good enough to remind me of those days with the Norfolk Symphony, which is now the Virginia Symphony.
Click to expand...

The analogy of live music only translates to a live scene. We're dealing with a recording here.
 


Henry

First you agree and say that it isn't any different. Then, you continue to explain how it is different. It is different in a very significant point, shadow detail. Extraction or compression development, as in the Zone System, has nothing to do with push or pull processing. I think we should stay away from confusing them. They are trying to achieve a very different thing.
 
clayne said:
It's for this reason, and what my eyes tell me, that I do not mind the lost shadow detail when pushing, honestly. For me, the subject and/or what's being said in the photograph is many times more important than so-called "fidelity."
Click to expand...

clayne

That might be a matter of taste or photographic role model. I don't like empty black shadows for the sake of someone needing a faster shutter speed or a smaller aperture. I prefer a continuous-tone photograph with detailed shadows and highlights, and a steep midtone contrast. Dmax on the other hand, is not my aim. Above 1.9 density, or so, there is little for the eye to differentiate anyway. As I said, probably a matter of taste, but we shouldn't really compare Zone System and push or pull processing. They are apples and oranges.
 

Oh, I must disagree. "Push" processing IS expansion development. If you increase the processing time from some normal value, it is expansion development. You are correct that it is being done to solve a different problem. It is being done to produce a full range negative after intentional underexposure as opposed to increasing the contrast of a scene with too little inherent contrast.

Henry
 
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You are correct, push processing is expansion development. But, in the Zone System expansion development, as in N+, does not lose shadow detail and simple film pushing does. That's a significant difference. N+ is done to lift highlights. Pushing film is done to increase EI. Another significant difference. Consequently, I don't see how you can claim that 'it isn't any different'.

Also, your explanation of the negative density range to stay constant is not quite correct. The negative characteristic curve is not linear. Making a linear horizontal adjustment of the curve (exposure) has a non-linear vertical response (density). In other words, pushing the shadows into the toe and the highlights down an almost linear portion of the curve has an effect on tonality. You are decreasing the negative density range, which forces you to print at a higher grade of paper. This changes print tonality even more and emphasizes the loss of shadow detail.

You cannot recover a lack of exposure with paper contrast.
 
clayne said:
The analogy of live music only translates to a live scene. We're dealing with a recording here.
Click to expand...

I was comparing live music to the tonally distorted recordings made by "flattening" the frequency response. If you look only at the bandwith, you think you have something good, but there are two parts to a frequency response: amplitude, and phase. Phase distortion was common in early days of Hi Fi. A common artifice is fold-back into the low end of frequencies beyond the upper band limit, which may make the bass boom alright, but you can hear the difference when you get an amplifier that has an upper band limit beyond human hearing. This fold-back happens whenever a digital sampling rate is too low as well as when the analog frequency response is too low. It happens in optical systems as well as in electrical systems.
 
Really, my question is: are there any type of specific tests that people use to determine pushing and pulling times?
Click to expand...

When you say pushing and pulling, what do you mean? Usually pushing film is to get more speed out of them...do you mean, expansion and contraction? N minus/plus in zone system parlance?

For expansion/contraction, I use the "zone board" method described in Gordon Hutchings's book on pyro...with a few adaptations of my own. It works really well, and only 5 sheets of film are required...if you shoot LF film, that is. Of course a densitometre is required or you can use your spot metre and a bit of math. After plotting the data (and I do this by hand on graph paper not on a computer like most BTZS people) I know all my N times and EI's to use for each N time.
 

if I push a stop and call it push processing, then the result is crap. However if I call it N+1 and invoke the religion of the zone system and follow the teachings of the great prophet Ansel, then the result is a perfect photograph.

I'm confused here.:confused:
 
noGuess I'd have to see the prints, one with tested EI for the film and tested development time, vs a print from a underexposed/pushed negative of the same scene. That's probably the only way to determine the value of giving a negative less than its optimum exposure,comparing prints. I know others will say it's the proper exposure for their system.

There are lighting situations I walk away from because I know I won't like the print.

I know there are lots of systems, in addition to Fred Pickers, that's what makes the forums interesting. Systems don't make good prints, people do.

Mike
 

The key is in the shadow exposure. In pushing, one combines reducing shadow exposure with developing to higher contrast in hopes that the very small rise in shadow contrast will keep the necessary shadow detail in the print. It is better in my opinion to set the exposure according to a spot reading of the point where you want maximum black by increasing your film speed to 4 times the box speed.

A good paper will show directly about 6.5 factors of 2 (f-stops) range. That is, if you apply your spotmeter to reading the brightness range of an excellent full scale print, it can read a maximum of 6.5 f-stops, even if the original scene showed 10 or more, so some compression must have been done by developing to a gamma less than 1.

Having set the shadow exposure, you must then estimate the gamma of negative development that will put the actual scene's highlight at the highest brightness the paper can muster. There is more to it than that, because it often happens that a single photo has more than one scene. In any case, trying to set film exposure without consideration of the material on which the negative will be printed is not the best way to go about it. The latitude of film on the overexposure side is so great that there is no need to try to push its toe farther into the dark side.
 

Correct, because N+1 does not mean a stop less exposure (that's why I sais let's not confuse the two). N+1 means to extend the development to lift the highlights by one zone (VII goes to VIII). This extra development also lifts the shadows a bit, which allows you to reduce the exposure by small amounts. In my case, Tmax-400 goes from EI 250 for N development to only EI 320 for N+1 development. This has nothing to do with push-processing.

I hope this explains the difference. No religion, no prophets, just the fundamentals of the photographic process.
 
Great thread.

I think I see the practical difference now, please correct me if I'm off the mark.
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N+, N, & N - development's purpose is to manipulate a negative's final contrast to make it fit a specific paper. The intent of the process is to make a great print easier; less filtering, less burning & dodging, being able to use the perfect paper, etcetera... There is no intent to use the film outside of it's natural range of sensitivity.
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Pushing & pulling are processes used to adapt a particular film to shoot in conditions outside the designed range of sensitivity, say using Tri-X 320 @ EI80 or @ EI5000. Over or under development are simply tools to get the best result possible given the mismatch of scene and media.
 

Bingo! I could not have said it better myself.
 

So what EI would you use for Tmax-400 and N+3?
 
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