> -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED]]On Behalf Of Julian Robinson > Sent: 27 November 2001 04:49 > To: [EMAIL PROTECTED] > Subject: Re: filmscanners: Nikon Scan DOES Vary LED Brightness
> If I was designing the thing, I would use a combination of both. Normal > gain would use the LED's at their maximum long-term brightness level - to > give shortest possible scan time. > > - Any *reduction* in "analog gain" would be by decreasing LED brightness > from that point or decreasing amplifier gain, so the scan time would > not change. > - Any *increase* in "analog gain" would be by increasing > integration time, That's a potentially nice solution. As I said earlier, the "blanking" time that occurs during each "thrum" step (there are approximately 300) lasts longer during an AG 4 scan, than during an AG 0 or AG -4 scan. > thus increasing scan time but not increasing LED brightness or > analog gain > beyond the normal maximum. This might fit with Jawed's observations > although I take Ed's point that I don't know how you can tell whether an > apparent brightness change is due to actual brightness change or > change in > the duty cycle of the LED (to accommodate changed integration times). I agree that you can't tell the difference. I wish that had occurred to me earlier. Ed asserted the scan speed is proportional to the analog gain setting. Well it isn't proportional. That's what's puzzling me. Jawed
