Cross over scan Imacon

[Spencer Ladd]

I have been scanning 4x5 Portra VC on an Imacon scanner with the latest software. My settings are Porta Negative, Custom Wht Balance, Single Shot, RGB16bit, 5000 Temperature, PPI 2040, saved as TIFF.

My proof sheets look fine (traditional C-prints), but I am getting a crossover of magenta in the sky and green in the shadows when I make a scan. Therefore, color corrections are more than difficult.

Does anyone have any experience with this problem? Does anyone have a extensive experience making scans of color negatives on an Imacon? Is there a protocol that will insure a better scan?

Spencer

[chacabuco]

I've run into the same thing with the Imacon. I also have a hard time getting a neutral shadow. The blacks quickly go green. I usually end up having to fix it in photoshop, though the cross curves can be a real hassle. Let me know if you find a solution

[Ken Allen]

Scan as 48bit color POSITIVE, with no tone adjustments or black or white point adjustments. In other words scan it as a negative master.
Then make the inversion and color corrections in PS. There are a few ways to do this, but you will find that when you get good, your color can be better than an auto setting on a scanner.
One very quick guide:
1. Invert
2. Make a curves layer (color1) and select the auto black point, adjust blacks slight if you need more detail, or the other way if you'll need more contrast.
3. Make another curves layer (color2) use the auto white point or manually adjust the white point on the RGB curves to get a good white.
4. Adjust the midpoints of the RGB curves (color2) to get the overall color balance.
5. Adjust the main curve on (color2) to get the correct contrast. Hint if the saturation gets too great, procede to step 6.
6. Make a third curves layer (tone1) set to "Lightness only". Adjust the main curve until the contrast is correct. You may have to share some of the contrast adjustment between color2 and tone1 to control saturation.

I'll try to improve these instructions and place them on my website.

Best,