scan much too dark after IT8-calibration

[gharhoff]

Recently I performed the tests to determine the scanners optimal gamma response again (as described in Ian Lyons Computer Darkroom-tutorial) and changed the gamma setting from 1.8 to 2.2. I had done this maybe 2 years ago and at that time arrived at 1.8. After the new gamma setting I wanted to recalibrate the scanner using the IT8-target supplied with Silverfast Ai Studio. Again I followed the instructions on the Computer Darkroom site. After this my scans are much darker than before (at least by 2 stops), and any shadows are completely blocked up. Slides that show shadow detail on the light box show none whatsoever in the scan. I repeated the calibration process several times, but the problem persists. After deleting the Silverfast prefs folder the scans are ok, but as soon as I calibrate the scans are dark again. Does anybody have an idea what is going on? Also after updating from Silverfast 6.6.0r3 to 6.6.0r4c the calibration feature behaves strangely: I get the window "calibration successful", and when I click ok a new prescan starts, sometimes also the SF launcher pops up. Any help would be appreciated, I need to scan a lot of slides soon. Thanks, Gabriele

Nikon Super Coolscan 9000, Silverfast Ai 6.6.0r4c standalone, scanned film Fuji Provia 100F, Windows XP Prof 32bit SP3. The IT8-target is a few years old and should probably replaced, but I don't think that is the cause of my problem.

[LSI_Ketelhohn]

Dear Gabriele,

please note, that the calibration is done at the set gamma. The calibration profile should always be used with the set gamma value.
If this is not causing you problem I would suggest you contact us via our support form so we can analyze your problem better.

kind regards
Arne ketelhohn

[gharhoff]

Thanks Arne,
I am aware of that. The reason why I wanted to recalibrate was the change of gamma. I will contact SF support. Gabriele