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Response to Need help with Tech Pan Negatives

from John Hicks (jbh@magicnet.net)
> The negatives came back with EXTREMELY high contrast and the highlights being washed out.

That's pretty much the nature of the beast.

TP will easily record seven to eight stops on the straight-line section of its curve shape, but above that things get weird.

The film may be capable of a high D-Max when developed to very high contrast, but when we develop it to pictorial contrast not only do we lower the CI to a usable level, we drastically lower the D-Max. So what happens is that above about a Zone VII to VIII exposure there's a _very_ prominent shoulder, with the curve going pretty much flat horizontal within a stop or two above that.

That's blocking; there is no significant contrast increase upon exposure increase.

Or iow, if you give a "full" exposure for shadow density, if the SBR is high enough you may easily push the light tones up onto the shoulder; this prints as pretty much blank white with no detail. If you burn it in, you end up with detailless grey.

The location and extent of the shoulder varies with developer; Xtol behaves exactly as I've described, with a rather early shoulder.

The best developer I've found for TP is C-41 developer (just the developer, not the entire process), use ordinary inversion agitation, 9'/75F for EI 12-25. It gives the longest straight-line curve section.

(posted 8731 days ago)

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