Negafix profile - 21 step wedge, blown highlights

[David Meriwether]

[Silverfast 6 Ai, default settings for generic gray profile; in PS7 on Mac G4, Epson 2450, firewire]

Scanning a commercial 21 step wedge in 4x5. Default settings for Grayscale/Negative/Standard. Used Negafix profile for TMax-100 (After viewing many options, it gave widest range on visual prescan.) Severe blown highlights, densitometer reading of 240+ as low as step 12 (compare to Zone 6 on 10 Step Scale). No differentiation in highlights.

Grayscale should read: 0-12-25-38-51-63-77-89-703-114-128-141-153-165-178-191-204-216-229-242-255
Scan imported to PS7 reads:
0-25-33-51-71-101-139-171-197-219-230-239-244-249-252-254 (at Step 16 with 5 more steps to go!)

In Negafix, I edited/saved a curve with much guess, trial and error over 4 hours. The Negafix curve is up against the extreme right vertical side on the high end, and attempts to adjust the highlights further darken the shadows and supress the highest value.
Scan imported to PS7 now reads:
0-25-34-43-48-56-66-80-92-110-134-158-177-195-212-225-234-242-246-250-254

Closer, but still no where near the accuracy in the deep shadows / highlights areas. Please advise how to proceed. Attempt to adjust curve requires severe changes to get densitometer readings closer in the steps, and is very uneven if not impossible. I work exclusively in B/W. How do I get an even step, reliable profile of grayscale standard?

[President_LSI]

Correcting blown highlights in NegaFix

The key to correct blown highlights in NegaFix is to edit the NegaFix curve accordingly. We have implemented a new zoom function to make that easier. Look at the movie to get the idea.

??<a href="/movie/en.html?filename=sf_curve2.mov" target=_blank>Movie</a>