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This question stems from the observation that my E6 chemicals tend to develop the film about a stop underexposed, and overexposing the film for one-stop during shooting seems to make the final image look about right, with no visible loss of detail in the highlights.

Many people would shoot at a higher ISO for faster shutter and push the film during development, which could add visibly more grain, but what about overexposing and pulling the film?

Is there a point where the overexposure is too much and the developed film becomes opaque no matter how much pulling is done? Or to say: when the development is trying to mitigate the over/underexposure during shooting, how many stops can the shooting deviate from the standard box speed before the image disappears?

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  • \$\begingroup\$ As a limit .. if you shoot directly into a bright light, no amount of pulling will restore the negative to show details of that light. So there has to be a limit somewhere. \$\endgroup\$
    – Peter M
    Commented Jun 12, 2023 at 20:19
  • \$\begingroup\$ Are you talking about color (E-6) or b&w process? Because with color film there is a color shift with push/pull processing which is very hard to control. \$\endgroup\$
    – Ankor
    Commented Jun 13, 2023 at 3:24

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The exposure and the development are not interchangeable — pushing film increases contrast, not sensitivity. Usually we push film when the contrast of the scene is low (e.g. in the fog), to expand the tonal range, and pull if the scene is overly contrasty and will produce an unprintable negative.

B&W film has much higher latitude in highlights than in shadows. The ISO speed encodes the minimal exposure that still allows to capture details in shadows, this is the way it is measured (it's described in ISO 6-1993 standard). Because of this, the shadows latitude (latitude from zone V down) is approximately 4 stops for any b&w film stock. The highlights latitude is usually much higher and varies between films and developers, usually it is 8 to 10 stops, sometimes more.

Such a high highlights latitude means that you can overexpose your B&W negative for 4–8 stops (depending on the scene contrast and the film stock) and obtain a perfectly printable neg without any changes in your development. Pulling will decrease the contrast of the negative, which is usually undesirable. In case of overexposure, it is required only if it is really massive one — e.g. for 10 stops.

However, overexposed negatives are dense, and while it's ok if you print (it will just make you to increase the printing exposure), if you scan, low-tier scanner can't get through these dense highlights. Usually if you see blocked highlights on your scan the problem is the scan, not the negative. The drum scanning allows to capture dense highlights the same way as it allows to capture dense shadows of a slide film. Pull development will indeed help low-tier scanner to capture the highlights, but the amount of pulling necessary depends on the scanner, and the price is that you will need to print on contrast grade if you are going to print optically.

If you want the image to completely disappear even when you pull, I think you will need to overexpose the b&w film for about 15–20 stops. 10 stops is certainly not enough. However, at overexposure like this, you are already close to the solarization effect, so there is a chance that even overexposing like this you will obtain some image on your film.

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