Re: filmscanners: exposing C41 for scanning ( was gibberish

[rafeb <rafeb@channel1.com>]

At 07:46 AM 6/30/01 +0100, you wrote:

>On Fri, 29 Jun 2001 05:16:18 -0400  rafeb (rafeb@channel1.com) wrote:
>
>>  Temperatures should be lower this weekend, 
>> so maybe I can check out the "heat" angle.
>
>Heat may affect lubricants and tolerances, of course. Which may impact 
>resonant behaviour of the mechanism
>
>> The "Super Fine Scan" checkbox worked quite dramatically 
>> on one image, while I was on the phone with the Nikon 
>> tech.  But the banding still appears occcasionally, on 
>> other images, even with this option selected.
>
>It was your earlier mention of this which suggested some sort of resonance 
>related to exposure. A stepper mechanism which carries an LED array and 
>pauses at each stepping to allow 3 (or 4, with IR) separate exposures is 
>going to be a tough exercise in precision engineering. Moreover the LED 
>array is swivelled to a different position for each channel exposure, or 
>at least that was how the LS1000 did it IIRC. An oscillating mass on the 
>end of a stepper seems bound to exhibit resonant effects at certain 
>frequencies, though whether this has any bearing on what you see I have no 
>idea.


Wow, this sounds byzantine, Tony.  Who invented that?

Not that I want to revive the flourescents-vs-LED thread, 
but if that's what's going on inside my 8000, I want no 
part of it.

I'm hoping (without evidence) that you're mistaken about 
the swiveling LEDs.  A 645 negative is approximately 
7,000 scan lines along the length of the strip (4.5 cm, 
at 4000 dpi) and that would mean 21,000 mechanical 
motions of the LED array (or 28,000 if you add the IR 
channel.)

I much prefer to believe they're switching the illuminant 
colors electronically.  Gawd, I sure hope so.  Too bad one 
can't poke under the hood and kick the tires when buying 
a film scanner...



rafe b.