Black Bias?

[KennyG]

My projector has a Black Bias adjustment...just what is this, and how can I tell of it's adjusted right?
KennyG

[JonMarsh]

That's an interesting term. My old Zentih projectors didn't use the typical nomenclature for brightness and contrast (which are sort of silly, also), but used "black level" for what is usually called a brightness control (makes sense, since it affects the threshold for the bottom end of the video transfer function), and "picture level" for the contrast, or video gain.
On a Sony projector, bias controls refer to the low setting threshold, as applied to each gun or color; there are bias and gain controls for each color, which are used for setting up gray scale tracking for each color, whereas the brightness and contrast affect the total picture luminance characteristics.

So, I would *guess* that your black level bias is setting the 0 IRE video threshold- what a brightness control does.

If I haven't muddled things up enough, let me know, and I'll take another stab at it.

-Jon




Earth First!
_______________________________
We'll screw up the other planets later....

[KennyG]

Thanks Jon, you've muddled thing up plenty!
I think you are correct, black bias does effect picture brightness. Another thing I've noticed when adjusting it, if I turn it down on each gun (say around 50 out of 100) it's almost impossible to get my gray scale step pattern (contrast) and brightness test pattern (with moving black bars) to BOTH look correct...however when I set the black bias higher, say around 80 it is easy to get these two patterns to look correct.
Also, I sent out the sound material today, so you should have it in a week to 10 days.
Kenny

[JonMarsh]

Thanks, Kenny. Really appreciate your donation!
Glad my guess seemed to be correct- your experience is what I would expect. Are you using VE or Avia for setup?

TGIF!

-Jon




Earth First!
_______________________________
We'll screw up the other planets later....

[KennyG]

AVIA