LaserSoft Imaging

PostPosted: **Sun Sep 29, 2002 6:03 am**

Apple iMac, 800MHz G4, 1GB RAM, 75GB HDD, 17" LCD monitor
Mac OS X 10.2.1 Jaguar
Nikon Super Coolscan 4000ED
IA-20 APS film adapter
SA-30 35mm film adapter
SilverFast SF-App v1.1.3
SilverFast AI (NikonM) v6.0.1d12

Lightness / Automatic exposure / Negafix exposure

I have found that most of the Negafix profiles I need to use produce very dark pictures. To get anything close to the original brightness, I need to set the Negafix exposure to +2.5 or +3. An alternate method is to open the Options window and change the Special > Lightness to a value of around -6 depending on the histogram values.

I am finding the three exposure-related settings mildly confusing.

The Negafix exposure setting works and produces great results. However, my film was exposed in normal lighting. Why should I have to apply a Negafix exposure setting of +2.5 stops to get 'normal' brightness? (All other colour settings are at their default values) This applies to Kodak and Fuji films, to 35mm and APS films.

I also wondered what would happen if I changed the lamp brightness instead of the Negafix exposure. While changing the lamp brightness in Options > Special, the Real-time preview and the Lightness histogram showed me the best value to use. In my case, it was around -5 or -6. While scanning and drawing the preview, the brightness of the prescan was lighter as expected. However, as soon as the prescan finished, the preview darkened as if the lamp brightness changes didn't exist.
(Note that all colour and auto-image enhancements have been turned off/reset. Only the Negafix profile has been selected.)

I then experimented with the Automatic exposure button on the Preview window but failed to see the effect of this button on the preview.

So please describe the relationship between the Options > Special > Lightness (Lamp brightness) setting, the Negafix exposure setting and the Automatic exposure button. Please describe how they affect each other.

Please also explain why changes to the Lightness value do not appear in the previews. Does the lightness value only apply to Positive scans?

And please explain why I need a Negafix exposure setting of +2.5 stops even though the photographs were taken in normal light.

regards
Gregory

PostPosted: **Mon Sep 30, 2002 4:18 pm**

Gregory C wrote:
Apple iMac, 800MHz G4, 1GB RAM, 75GB HDD, 17" LCD monitor
Mac OS X 10.2.1 Jaguar
Nikon Super Coolscan 4000ED
IA-20 APS film adapter
SA-30 35mm film adapter
SilverFast SF-App v1.1.3
SilverFast AI (NikonM) v6.0.1d12
Lightness / Automatic exposure / Negafix exposure

I have found that most of the Negafix profiles I need to use produce very dark pictures. To get anything close to the original brightness, I need to set the Negafix exposure to +2.5 or +3. An alternate method is to open the Options window and change the Special > Lightness to a value of around -6 depending on the histogram values.

I am finding the three exposure-related settings mildly confusing.

The Negafix exposure setting works and produces great results. However, my film was exposed in normal lighting. Why should I have to apply a Negafix exposure setting of +2.5 stops to get 'normal' brightness? (All other colour settings are at their default values) This applies to Kodak and Fuji films, to 35mm and APS films.

There might be a differnt light temperature taken as reference for profiles.

I also wondered what would happen if I changed the lamp brightness instead of the Negafix exposure. While changing the lamp brightness in Options > Special, the Real-time preview and the Lightness histogram showed me the best value to use. In my case, it was around -5 or -6. While scanning and drawing the preview, the brightness of the prescan was lighter as expected. However, as soon as the prescan finished, the preview darkened as if the lamp brightness changes didn't exist.
(Note that all colour and auto-image enhancements have been turned off/reset. Only the Negafix profile has been selected.)

That profile makes the difference. SilverFast is "frame orientated" that is SilverFast takes into consideration all that is inside the drawn scan frame.
As soon as the preview data is complete SilverFast applies the corrections defined by the NegaFix profile. That's why it changed in the end - the data was read by hardware with your lightness settings, and afterwards the NegaFix profiles corrected this data.

I then experimented with the Automatic exposure button on the Preview window but failed to see the effect of this button on the preview.

Was this the brigtness (sun) button? this only takes effect when data is transferred - preview or scan.

[regards
Gregory

LaserSoft Imaging

Lightness, exposure, negafix

Lightness, exposure, negafix

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