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PUSH PULL AND OVERATED DROP DOWN AND GIVE ME 24
Old 11-15-2002, 12:05 AM   #1 (permalink)
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O.K.......having never actually been in a wet darkroom and at this point in my life probably not about to start, I have a basic question. I understand and use the concept of underating or overating film, say shooting Kodak NC 160 at 125.

I understand that you can push film like shooting 800 speed then pushing to 1600 and pulling film too, but what is the "effect" or result obtained or achieved by either in contrast one to the other.

If I shoot 3 rolls, one pushed, one normal, one pulled and lay the photos side by side
what difference do I see?
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Re: PUSH PULL AND OVERATED DROP DOWN AND GIVE ME 24
Old 11-15-2002, 12:21 AM   #2 (permalink)
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Simply put pushing film (underexposing and increased development) increases the film speed but also increases grain and contrast.

Pulling film (that is overexposing and underdeveloping) decreases contrast.

You asked: "If I shoot 3 rolls, one pushed, one normal, one pulled and lay the photos side by side
what difference do I see?" See above explanation.
 
 
Re: PUSH PULL AND OVERATED DROP DOWN AND GIVE ME 24
Old 11-15-2002, 12:53 AM   #3 (permalink)
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Contrary to popular opinion, pushing or pulling film does not change the "speed" of a film one iota. Pushing a film means to extend it's development. Pulling a film means to shorten development.

Exposure increases an image's density in both highlight and shadow areas roughly equally (actually it's a curve, this is what is referred to by the term "characteristic curve," the amount that the density of a film will increase as exposure is added). Changes in development, however, have a much more pronounced effect in the highlights. This allows one to change the overall contrast of a film, as the shadows pretty much stay put, but the highlights go up (in the case of pushing) or down (in the case of pulling). Some photographers, in a pinch, utilize pushing to compensate for a lack of exposure. This is really a last resort, because, as I said, the underexposed shadows will remain just that, underexposed. The mid-tones, as well, will be a bit thin and muddy. Only the highlights will truly exhibit proper exposure, and this comes at a cost, increased grain. One could also compensate for overexposure by pulling a film, at the cost of flattening contrast.

Ideally, pushing and pulling are contrast controls. Pros who use chrome films push and pull all the time in small amounts (say 1/3 of a stop) to control their contrast.

So, to re-iterate, "pushing" is an increase in development, which increases the density of highlights, thus increasing contrast, simultaneously increasing graininess, most especially in the highlights. "Pulling" is a decrease in development, which decreases the density of the highlights, thus decreasing both contrast and, to a certain extent, grain.

Finally, the rating of a film's speed is actually the rating of how much exposure is required for the film to begin to record density above its film base and fog, in other words, the density of the shadows. Changes in development have little impact on these shadows, so a film does not get any "faster" by pulling it. Just to get that straight.

Hope that answers your question. Some very basic knowledge of development is essential to a photographer.
 
 
If you \'ve never been ...(N)
Old 11-15-2002, 12:55 AM   #4 (permalink)
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If you've never been in a wet darkroom, then your photographic education is severely lacking. What happens in the camera is only about half of the photographic process. I've no doubt some (maybe many) will argue with me, but without an understanding of the wet process, you are sort of phucked!

I coulld write an entire book on this specific subject (maybe I will?), but when we push or pull a neg, we are playing with highlights and shadows. A given film has a specific level of light sensitivity which is determined by the amount of light sensitive silver, or dye couplers for color film, placed in the film during manufacture. We can't change that! When we 'push' film, we make an intentional underexposure which is then compensated for by intentional over developement. We either prolong development or use an overl;y energetic devolper. By doing that, we sacrifice highlights in favor of shadow detail. In other words, we throw away highlight detail in favor of shadow detial. In 'pushing' film, we gain contrast and grain. When we 'pull', we intentionally overexpose, giving up shadow detail in exchange for highligh detail, the precise opposite of pushing. When we 'pull' we overspose and under develope; when we 'push', we underespose and overdevelope.

In the attached photo, the 100 speed film was rated at 800, with a gain in cointrast and grain. The grain increase is not really visible in the small ditgital image.

Distinctive images

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Re: If you \'ve never been ...(N)
Old 11-15-2002, 01:10 AM   #5 (permalink)
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Thank you for echoing my sentiments on at least understanding the fundamentals of the darkroom. Without any knowledge of the darkroom, only one half of a neg or transparency is controlled.

Unfortunately, terms like "push" and "pull" are used differently by different photographers. I was always taught that a push or a pull is quite simply a change in development, and when pulling one generally compensates by overexposing (though pulling can also be used correctively, when you didn't intend to overexpose but had no choice, as when shooting in sunlight and your highlights are too hot for the necessary shadow exposure), whereas when some photographers refer to a pull, they are referring to both intentional overexposure COUPLED WITH underdevelopment. Thus I like referring to "increased" or "decreased" development, though of course when talking to labs I always tell them to "push this or pull that X stops." Zone system gurus talk about zonal expansion or contraction, but they're referring to the exact same thing, with a different terminology.
 
 
Re: If you \'ve never been ...(N)
Old 11-15-2002, 09:19 PM   #6 (permalink)
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Thank you all for the detailed explanations. Some of you hit on my confusion and now I understand. Some people talk about pushing a film when they know they have underexposed and are trying to salvage it. Other people shoot normal and "push" for the contrast it provides. The guy that is salvaging an underexposed roll is simply interested in getting usable prints and lives with the outcome, the guy that is pushing on purpose knows what he wants. I had heard the term used 2 different way, now that makes sense, but each camp that uses the term normally assumes the listener understands the way in which it is being used.

For my next basic question.... How to I pull the leader out of a CF card so I can get in the wet darkroom? I should have mentioned that I am shooting a D1x for the most part nowdays so I think I would really be phucked if I dropped my CF cards in a vat of liquid. [img]/ubbthreads/images/graemlins/smile.gif[/img]
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