I'm with inan c -- the metering is fine, but the subject is just too dark in front and trying to compensate just by exposure is going to make it harder to get the rest correct. Either a teensy fill flash, or just a reflector of some sort, someone next to you holding a big sheet of white cardboard or foil-covered or something, anything to throw a bit of light on that very lovely lady.
Thanks all for your info. I guess 160 iso for this film is fine. And yes, she in shade so she should be dark. The main error here is how i composed the shot with not enough difference in tone between my subject and the background. Exposing for longer would not change this relationship. So yet portrait falls down on not having enough light on the subject. I now have two reflectors, which will be an option for next time and i have a leaf shutter lens on the way so maybe a softbox also!
Thanks again all for the insights. am not sure i would have cracked it on my own.
Aren't you by chance using a Pentax 67?
Suggest a back-to-basics metering strategy:
Spot meter face (1: in this image the face is a critical fail as it is improperly illuminated), left arm (illumination side) (2) right arm (3), front of dress (4) forward bottom left grass (5), then average all. No spotting of spectrals in background or bright grass.
A flash should not be needed but can be usefully employed with spot metering and baseline-averaged fill-in flash with the softbox you spoke of.
.::Gary Rowan Higgins
A comfort zone is a wonderful place. But nothing ever grows there.