Originally Posted by ChrisPlatt
Perhaps this film's true speed is a little lower than 100.
Has anyone else tried shooting it at EI 80 or 64?
Yes, I have.
I've got best results with EI 80/20°. I've used calibrated exposure meters.
I have also shot Provia 100F and E100 side by side: Same conditions, same camera and lens. Provia 100F is perfect at box speed of ISO 100/21°.
E100 is best at EI 80/20°.
The contrast curve of E100 is also a bit steeper than Provia 100F (resulting in a bit higher dynamic range Provia has).