B&W Negative Exposure Question

[IanBarber]

After doing a Prescan on a black and white negative, the image changes brightness and contrast depending where you put the red selection.

on 5x4 sheet film, Include the film edges and you get a different exposure to when you do not include the film edges.

Can anyone explain why this is.

[LSI_Ketelhohn]

Dear user,

The NegaFix function is based on the histogram of the area inside the red scan frame.
For correct transformation place the red frame tightly around the image borders.


Kind regards,
Arne