Pushing adds contrast by lowering the values of the shadows while theoretically keeping the high midtones where they would have been if the film's ISO was actually what the film was rated at, and raising the value of the highlights. It should definitely raise contrast and make the brightest highlights very bright. If the details in the high mid tones block up when you do this, it just means you have pushed unnecessarily, or too far.
To understand it, it helps to look at S curves for a normally exposed and processed film and for an underexposed and overprocessed film; preferably on the same graph. What you are doing by pushing is creating a more contrasty film, so yes, it does become harder to capture detail in the higher tones and the lower tones simultaneously. Imagine taking a technically-difficult, high-contrast film like Iford Pan F and making it an 800 or 1600 film. That is basically what you get when you push 400: a high speed film with the contrast of a low speed film.
Everybody who often shoots in low light hand held has made the mistake of pushing unnecessarily and losing more from the high end than they wanted. Better judgment of the contrast in which you are shooting (AKA lots of practice and printing of the results) helps, as does a spot meter.
Some tricks I have used to lower contrast in low-light shots that I have mistakenly overdeveloped are split-grade printing, two-bath lith printing, shadow masking, or copying a low-contrast print on to sheet film and altering exposure and development of the sheet film to get contrast where I want it.
Sometimes, in low light that is contrasty, it is better to underexpose and leave development as normal (or to "stand" develop) for this very reason.
However, for me, the whole purpose of pushing is to favorably capture the mid tones on the neg with the density and contrast I want. I don't mind dropped shadows or blown highlights in most low-light hand held pictures; not one bit. I think the contrast often suits the subject matter
To understand it, it helps to look at S curves for a normally exposed and processed film and for an underexposed and overprocessed film; preferably on the same graph. What you are doing by pushing is creating a more contrasty film, so yes, it does become harder to capture detail in the higher tones and the lower tones simultaneously. Imagine taking a technically-difficult, high-contrast film like Iford Pan F and making it an 800 or 1600 film. That is basically what you get when you push 400: a high speed film with the contrast of a low speed film.
Everybody who often shoots in low light hand held has made the mistake of pushing unnecessarily and losing more from the high end than they wanted. Better judgment of the contrast in which you are shooting (AKA lots of practice and printing of the results) helps, as does a spot meter.
Some tricks I have used to lower contrast in low-light shots that I have mistakenly overdeveloped are split-grade printing, two-bath lith printing, shadow masking, or copying a low-contrast print on to sheet film and altering exposure and development of the sheet film to get contrast where I want it.
Sometimes, in low light that is contrasty, it is better to underexpose and leave development as normal (or to "stand" develop) for this very reason.
However, for me, the whole purpose of pushing is to favorably capture the mid tones on the neg with the density and contrast I want. I don't mind dropped shadows or blown highlights in most low-light hand held pictures; not one bit. I think the contrast often suits the subject matter
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