[filmscanners] Re: CRTs vs LCDs

["Dave King" <kingphoto@mindspring.com>]

>Dave asked:
>>Well, I was satisfied by Julian's answer, it was easy and practical.  But
>>your answer has me wondering again about what is actually happening at the
>>circuit level.  I guess they are voltage amplifiers operating at different
>>frequencies?  Presumably the gain control isn't particularly critical in
>>real world terms for color correcting work (all I really care about), but
I
>>wonder why.

>The bias controls (three, one for each colour) in effect adjust a voltage
on one of the CRT electrodes to give >individual brightness adjustment of
each colour. They are set to give neutral blacks.
>
>The gain controls (again, one for each colour) set the gain of the video
amps in the monitor and are adjusted to give >neutral whites. With luck, or
a good quality monitor, all the grey levels are also neutral, but if not,
that is where a utility >such as Adobe Gamma comes in.
>
>Both white and black settings are important for colour correcting work
Dave, perhaps the black setting being the >more ctitical one.
>
>Colin Maddock

That's helpful, thanks.  I misspoke in my earlier comment, I meant to say
*bias* (not gain) is presumably not particularly important since ColorVision
said something to that effect to Julian.  Quote from Julian: "I asked about
the bias controls, and I was told to leave them at the factory settings."

But you seem to be saying that the bias setting is more critical than the
gain setting.  So if you and ColorVision are both correct, then factory
setting for bias is fine to use, and presumably there isn't as much drift
here because phosphor aging isn't an issue in the black tones?

Thanks again,

Dave



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