Highlights in pull/push processing

[Emilio Schlappi]

Dear all,

 

In stills photography, giving the negative extra development time increases contrast by extending the highlights, and less development time reduces contrast by bringing down the highlights. The shadows are much less affected in both cases. Do you find this to be true of modern film stocks, too? How much does forced processing really, visibly, affect the newest emulsions?

And finally, what changes in the lighting do you make, if any, to compensate for the anticipated changes in contrast?

 

Many thanks for your time,

 

Emilio

[John Holland]

From my experience pushing neg lowers the contrast , its the other way with reversal stock !

[Dominic Case]

Push processing does increase contrast overall and more particularly at the highlight end of the scale.

 

But it also increases the fog level (d-min), so at the exttreme shadow end of the scale, contrast tends to be reduced - this is how you get the effect of seeing slightly more into the shadows.

 

Since push processing is often used to compensate for under-exposure, it is the shadow wnd of the scale that you are more interested in.

 

Modern colour negative stocks are more resistant to all processing variations. So - for example - a 20% increase in dev time has less effect than it would have done on a pre-Vision type of emulsion. I suspect labs are generally reluctant to physically increase the push-process correction to allow for this resistance, as such dramatic variation from the norm may introduce other unreliable effects or issues.