PEI, Push-Pull, Exposure Confusion

[DanK]

Not sure I see your point. What does it matter if I use the shutter speed, aperture, ND filter or step wedge in front of the negative to stop down my zone V reading to zone I. Using a step wedge and exposing at zone V, in one shot, I know to what the ISO correction should be to get the zone I - it is just a matter of counting the step number that registers 1/3 step above fb+f in the negative.

A densitometer is just another tool....

The adjustments you mention will get you in a direction - but how will you define your starting point or reference point?

The weak link may very well be visual assessment of the results....

Thanks,
Dan

[mmmdoughnuts]

but how will you define your starting point or reference point?

This is my starting point, but I should have been Zone X instead of Zone V in my previous statement. You are correct that it is all visual, but I should only be off by less than 1/3 of a stop with my 31 step wedge, but the instructions below are for a 21 step wedge.

http://www.paulwainwrightphotography..._your_eyes.pdf

Where he says:

If Zone zero shows no difference in density from the step(s) just above it, then the film has received insufficient exposure. In this case, it is easy to judge how much additional exposure is needed: count the steps until you can see good density changes on the negative....Where you begin to see density changes, that step is Zone zero. Since each step represents a half-stop change in exposure, it’s possible to calculate how to change the exposure index. For example, if I set my light meter to ISO 400, and significant density changes are seen only down through the 3rd from last step (step 19), then that’s actually receiving the Zone zero exposure, and the film speed on the light meter needs to be set at 200 to give one stop more exposure to the film. I then repeat the test to double check my assumptions. The film speed I’ve chosen at this point will be the one I’ll use for this film.

This makes sense to me.

Thanks for the help!

-Andy