Pre-flashing Direct Positive paper from Ilford Harman
I am proposing to use Ilford Harman Direct Positive paper in my half plate camera.
Does anyone have experience of doing this? If so how, and for how long, do you pre-flash the paper to reduce the contrast, prior to the main exposure?
I have read the information sheet produced by Ilford Harman, but this is not making much sense to me! The notional speed of the paper is 3 ASA. Is there a formula to decide what % of the metered exposure should dictate the pre-flash exposure time?