jackm1943 Loc: Omaha, Nebraska

VueScan has breathed new life into my old Epson 2450 and new Windows 7 combination. I am using it like RAW to save images from 120 and 4x5 negatives scanned at various "Brightness" values that I think are about 2-stop differences. The images are then inserted into Photomatix for HDR output. It works pretty good.

My question: Is a two-fold change either up or down in Brightness the equivalent of a 2-stop or 2-EV change? If not, what is?

I contacted the VueScan programmer and he had no idea. I'm hoping someone in UHH land is also doing this and had more experience that me.

Thanks, JackM

lynn1

I'm not sure what you mean, but one step change in your exposure doubles the time your lens is open.

jackm1943 Loc: Omaha, Nebraska

Hi Lynn, thanks for your comment.

In HDR, one usually wants to use images that are about two stops different from each other. Typically, one image at correct exposure, one at 2 stops underexposed, and one at 2 stops overexposed.

VueScan allows you to increase the brightness up and/or down, much like in RAW formats, and then save these different images of the same scan at various brightness levels. What I don't know, and neither does VueScan inventor and progammer Ed Hamrick, is what brightness settings provide a plus 2 or minus 2 stop difference in the image.

Just from trial and error, and using my eyeballs, it appears that 2-fold changes in the VueScan Brightness setting results in about a 2 stop change in the image, either up or down. For example, if a Brightness setting of 0.6 provides a "normal" looking image, then I would save copies at 0.3, 0.6, and 1.2 Brightness settings and use them for HDR purposes. I am trying to find if anyone else is doing this and if they agree with my findings.

Thanks, Jack