What is the difference between PUSH and N+1

lhalcong

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What is the difference between pushing a roll 1 stop in processing And. Processing a roll of film at N+1.

Please note that I have already learned my N+1 times for the film I shoot. And I also understand the concept of pushing. However from processing point of view , how are they different from each other. ?
Can PUSH actually move all the zones up 1 stop. ? I don't think so but I have to ask.

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Please se note that the reason I'm asking is because I exposed a roll of TMAX 100 accidentally moved the aperture dial to F/8 when I had measured the light at F/5.6 while shooting a baby with speedlights. So I'm guessing I should push 1 stop in processing.? I normally use D76.
 

polyglot

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They are both an extension of development time, but for different purposes and generally by a different amount.

N+1 means that the contrast will be expanded such that there are now only 5 (metering) stops between Zones II and VIII on the print instead of 6 stops.

Push+1 means "make it so that metering a midtone one stop faster will still come out at Zone V". This is achieved through a combination of both speed increase and contrast increase from the extended development.

If you've done detailed BTZS measurements to obtain your N+k times, you can interpolate the development time from your graph of speed-points (preserves shadow detail but probably gives you way too much contrast). Or you can develop for somewhere between N+1 and N+2 which will give you about the same development as 1 stop of pushing.
 

joh

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I'm looking for the same thing in moment. I tested Tri X in Atomal49 1+1 and get a real speed of ISO400/27 for Zone I. If I set the reference value to Zone V (for Pushing), it seems that a N+2 development time also can be used to bring my Film to a "pushed speed" of ISO1250/32. The density for Zone V is the same, the density from Zone VII goes to VIII. With a N+3 development I could also use ISO 2500/35 and the density of Zone VI 1/2 is the same as my VIII in N development.
I interpolated this data and did not test it in the real world yet. But I think it's funny if it works. I could use a film in the camera for two different tasks.
For N+1 development it seems I could use it also for bringing the film to ISO800/30 and Zone VII1/2 has the same density like VIII in N Development.
I hope my thoughts are not to incomprehensible...and sorry for my english
 

jcc

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From the development side, they're kind of the same. The key difference between the two is in the exposure side. For example, pushing would expose the darks as if the film had higher ISO, while N+1 would expose the film at its normal ISO.
 

David Allen

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The only way you can 'push' film is by taking a 35mm or roll film and pushing it with your finger along a table!!

Seriously (above is just a reference to my deep dislike for the word 'push'), there is a real and significant difference.

In N+1 development, what you are doing is placing significant shadows of Zone III and then extending the development to deliver an increase in the contrast so that you achieve highlights that render a slight amount of detail (Zone VIII).

In 'push' processing you are doing something quite different. You are rating your film at a higher ISO than that indicated by the manufacturers or that you have identified through testing for your own personal EI. In doing so you are accepting:
  • Loss of shadow detail and moving the highlights lower down the curve.
  • The need to expand the tonal range of what information you have recorded to move the highlights back up the curve with the recognition that the lower shadow areas will be rendered solid black but in the hope that the extended development will deliver good tonal separation over the mid-tones and highlights.
  • An increase in visible grain.

Both approaches are valid if they deliver the results that you want. However, every film has a basic fixed sensitivity (which varies slightly with developer type / agitation / temperature) and cannot be changed to a higher ISO by 'pushing'. What you can do is to consciously sacrifice shadow detail and then extend development to expand the tonal range of what information you have recorded.

Bests,

David
www.dsallen.de
 

markbarendt

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There is no difference in the development tank. Either simply makes the film curve steeper.

Also, the usable/real speed point of the film doesn't change very much, depending on how you measure it may not change at all.

The exposure placement is different though. With a push, shadow detail is willingly sacrificed to keep the aperture and time settings in a workable range to control DOF and blur.
 
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lhalcong

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ok, thank you for the answers. so what do I do in this case

Now, since I have exposed the roll at F/8 when the flash had been metered at F/5.6 (moved the dial by mistake without realizing), I am one stop underexposed. Of course I see this similar as to have to push the film. However as many of you mentioned, the shadow detail on the low zones may have been sacrificed. However , in my attempt to rescue the shots my best possible I intend to push the film one stop. My N+1 is 30% , but I dont want to up the highlights too much either. so will this below approach work;

Develop somewhere at 30% more time but reduce agitation so as to keep the highlights in control / Does this make sense and will it help me here ? that is, help middle zones a bit, but without blowing highlights too high ?

thx
 

markbarendt

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A push isn't the only option here. Your choice of developer can make a difference. DD-X, TMax, or similar will give some real speed difference.

That said a one stop underexposure for most negative films may not even be noticeable in the print.

If the shots on the roll you have already shot are really important shoot another roll the same way as a test, cut it in thirds, develop one normally and see if it works well and prints well. If so you're ready to develop the important roll if not experiment one at a time with the other two test strips.
 

Vaughn

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Way back in the dark ages, I heard that to increase contrast in the negative, one should also slightly decrease the exposure as well as extending the development. I took a quick look in AA's The Negative, but could not find the reference quickly (ahhhh...the negative effects of Google on our habits!). If that tidbit of info from the past is true, then pushing and N+ developing start to sound even more alike.
 

Vaughn

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Michael R 1974 said:
That's a myth, particularly with current long scale films.
Click to expand...

Interesting. Decreasing the exposure and extending the development could give greater contrast than extra development alone, but as you said, may not be needed with today's film. The one little bit in The Negative I did read mentioned the difference between older and more modern films -- in modern films the toe will move a little with more development whereas the older films did not. Of course the reference to "modern" films mentioned was 30+ years ago!

In my own work, I often use the reciprosity 'failure' of the film to increase contrast. My exposure times tend to be many seconds to many minutes long -- I have been known to nap during 30+ minute exposures under the redwoods!
 

DREW WILEY

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I suspect the term "push" was borrowed from color lab terminology and has been basically misapplied to black-and-white darkroom work. In these circumstances it often can be translated into, "I screwed up the exposure, so now how do I try to salvage it?" The that other highly abused term,
"latitude", keeps coming up with reference to this. But all such generalizations are relative to not only the level of exposure of specific kinds of film,
and to the type and degree of development, but to the nature of the curve shape of the film (esp in the toe area), and to how you intend to print it.
For example, a steep-toed film, when underexposed but overdeveloped, might give you very nice midtone gradation, but the deeper shadows, if relevant,
will basically be blacked out. A long toe film might survive the error, but the gradation down there might be muddy and disappointing. And a few films,
even in this day and age, might blow out the highlights, over the top of the curve, with overexposure. There are simply no cut and dried formulaic answers
that apply to every situation. You need to become experienced with you chosen films, developers, and papers. The good ole Zone System is simply a
shorthand way of sorting out your shots for varying regimens of development, but hypothetically differs with every other variable you apply to it. And
someone like Vaughn, who tends to work with very long-scale contact print processes, is going to have a different result than someone printing in
conventional silver-gelatin media.
 

DREW WILEY

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P.S., Michael - It's not a myth. The rules of sensitometry haven't changed at all, even though most of the specific films, developers, and papers on the market have. Not all films are the same. Some will forgive you more than others. But then, if you prefer a high-performance
vehicle like a Ferrari, you can expect an occasional crash if you're going too fast. I happen to love films with a very steep toe and a long
straight line because they tend to give excellent shadow separation even under extreme lighting ratios, esp in pyro developers. But for that
very reason, you have to expose them carefully; or if you do intentionally break that rule, understand the outcome. But when I'm out snapshooting with a Nikon, as opposed to my 8x10, I might take a completely different strategy and choose something like Delta 3200,
which has a distinctly long toe.
 

DREW WILEY

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I've never heard it explained that way, Michael, but I guess that in the sense of little exposure transpiring in the shadows at all, the apparent contrast in
the print itself might come out greater, if one doesn't mind lack of detail in the shadows. I've sometimes done that, kinda the ala Brett Weston graphic black shadow look, with the mids all expanded. But with respect to how films have changed, they've actually become less flexible in the modern era.
The engineering objective seems to have been to recoach silver to become more efficient cost-wise, and at the same time reduce grain size to accommodate for the gradual shift to smaller and smaller cameras. But other desirable characteristics have been sacrificed. I doubt that any current film is as malleable as the old-school standby Super-XX, for example. We do have some remarkably versatile products available, like TMax 400, but there are
still certainly some old timers lamenting the loss of the past classic films, esp the contact printers.
 

Vaughn

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Michael R 1974 said:
It's not that the sensitometry has changed, rather that the notion underexposure increases contrast is not sensitometrically sound.
Click to expand...

Sounds smounds...it is what the print looks like that matters.. (please note a lack of seriousness).

Since I contact print in alt processes, I do enjoy have very small areas (too small to see any detail in with out a high-power magnifier) that are clear on the negative. With carbon printing, they add a sense of depth and increase the effect of the raised relief in the image. I also about double the "normal" development (and/or use paper developers) to 'push' the highlights further than most people would dare. Resiprocity 'failure' (basically underexposing the shadow areas only) helps keep the shadow areas from being dragged too far along with the mid-tones and highlights, giving me the contrast I love and adore for alt processes.
 

cliveh

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Why would you want to push film? Why not get the exposure correct at the outset?
 
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lhalcong

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I did not meter as to placing the shadows or highlights. The scene is; father with baby on a chair out on balcony and under tree shade. Because ambien light level was too low, I used flash bounce off white umbrella and meter the light falling on the chair at F/5.6 . but then set the dial to f/8 by mistake and I realized at the end of the roll.
 

Vaughn

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StoneNYC

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cliveh said:
Why would you want to push film? Why not get the exposure correct at the outset?
Click to expand...

Sometimes you don't have the right speed film, sometimes they don't MAKE the right speed film... (No D3200 in LF) sometimes the look you want is better achieved by pushing, sometimes you're stuck in the Grand Canyon and all that's left (Because the US Postal service's "guaranteed on time delivery"... Failed...) is PanF+ and you're using a red filter on a cloudy day and you know the wind is blowing too much for a long exposure shot to come out well so you push it to 200
 

markbarendt

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Clive makes a good point, pushing doesn't significantly change what a film can actually capture/where the shadows fall/the real film speed.

Given that we aren't gaining much, if any, speed; what's the point?
 

StoneNYC

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markbarendt said:
Clive makes a good point, pushing doesn't significantly change what a film can actually capture/where the shadows fall/the real film speed.

Given that we aren't gaining much, if any, speed; what's the point?
Click to expand...

Have you ever used Delta3200 at 400, and then at 1000, and then at 1800, and then at 3200.... I beg to differ, yes technically it's a 1000 speed film that pushes to 3200 very well, but I've known people who said they pushed it to 6400 (I haven't) but I HAVE pushed it to 3200, and I've pushed PanF+ to 400 (once, it was an accident, I shot it thinking it was TMY-2, not on purpose, and when I pulled the roll out I was like ahhh!!! but I still got an image even if it was contrasty...

PanF+ in Rodinal 1+50 pushed 2.5 stops

 

cliveh

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Stone, is pushing film part of your simplification of practice programme?
 

markbarendt

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Stone you're actually kind of proving my point. There is a huge difference between shooting at 400 or shooting at 6400, the point at which the film starts creating shadow detail changes roughly 4 stops..

Exposure controls the amount (and quality) of detail caught, that's not a development thing, it happens regardless of which EI the film is developed for, assuming the same developer.

Don't mistake the latitude and adaptable nature of negative films for a real change in where the detail starts. Straight printing rarely uses the entire range caught on a negative.

Sure on your Pan F example you bent the toe of the curve up enough to salvage the shots with push development, and you very possibly turned those shots into nice prints: I am not saying that can't be done, but did those shots really look like Pan F shot normally or like the T-max would have? No. You changed the qualities/characteristics. More contrasty right? The look of the grain changed too. The way the tones printed was surely different from the normal Pan F or the original T-max straight line you were hoping to print from.

I regularly shoot my Delta 400 anywhere from 50 to 1600 without any change in development (DD-X per Ilford's sheet for normal contrast (EI500), and can make virtually identical prints across the whole range. At 1600 I'm hitting my detail limit.

So why would I push if I'm in that usable range?
 
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StoneNYC

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I don't optically print, I scan, and when it's under exposed, if I try to increase the total exposure, the blacks show this bad grain that looks like efke-itis, but it only appears on an under exposed image that I try to scan at adjusted exposure, so I would assume this would happen with printing too? But don't know, either way, underexposure doesn't look as good as pushing.

And actually this image inspired me to do some other pushing for a purposeful contrasty look.

Anyway I can't verify your printing an under exposed negative so I don't know.
 
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