CurtPalme.com Home Theater Forum

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

WTS · Joined: 08 Mar 2006 Posts: 1276 Location: Calgary

Yes of course you'll higher lum readings but then you don't take any colour shifting/tinting that the screen might cause/add into the grayscale calibration. I think I prefer to point at the screen just for that reason.

Kal, I find it odd and unlikely that your R and G cutoffs end up being the same.

tommo2 · Joined: 03 Jun 2006 Posts: 226 Location: Ireland

Of course you will get more foot lamberts facing the projector, especially going nearer to it. When we look at a screen we are interested in measuring the reflected light from it. This is what we see when we look at the screen.

We couldnt give a toss what light intensity is hitting the screen. The picture we see is what is reflected off the screen. Hence we measure the reflected light from the screen.
This only really applies to front projection, as with LCD and plasma we do see the light intensity emitted.

I think this is why kal says to set the HCFR to lcd.

Hope this makes sense, and I have grasped this right.

**kal** · Posted: Sun Apr 20, 2008 2:19 am Post subject:

garyfritz · Joined: 08 Apr 2006 Posts: 12088 Location: Fort Collins, CO

**kal** · Posted: Sun Apr 20, 2008 1:10 pm Post subject:

WTS · Joined: 08 Mar 2006 Posts: 1276 Location: Calgary

Hi Kal,

I forgot you're using a Spyder probe which doesn't require a cal file, only if you use the HCFR probe do you need a cal file. My probe is pointed upward slightly trying to get the same ( reverse ) angle as the light from the tubes is hitting the screen with the sensor about 1" away.

As far as the gamma goes, it all depends on who you believe some say 2.2, some say 2.5 and then others say anywhere in between 2.2 - 2.5. There's nothing wrong with my shadow details as far as I can see.
So changing what will bring the gamma curve down?
Actually my brightness setting was 55 not 47 like I noted. I noticed your ftl luminace are way higher than what mine are, yet your contrast is only 5 clicks higher than mine and I have a 1.5 gain screen and you have a 1 gain screen, or is your screen gain higher. Again it might be the probe factor too.

It's actually hard to compare our data because we're using different probes, I doubt even the same model probes would give the same results on the same projector let alone different pjs, unless of course you're using $1k+ probes. Would be nice if theses probes came with calibration curves so you could compensate for their short comings.

I learned not to trust my eyes for the proper settings after I got my first Minolta analyzer and saw how far out it really was.

I wish there was a fine gain/bias control on these 1200's because I find that one click either way can change the readings in the continuos mode more than I like.

**kal** · Posted: Mon Apr 21, 2008 1:45 am Post subject:

perisoft · Joined: 29 Aug 2007 Posts: 2920 Location: Ithaca, NY

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

An update with the Eye One Display 2 LT, It works very well, have been playing around with the diffusor on and off and get very similar readings both ways, as long as you make sure in the setting you select either useing or not using the diffusor. Kal the calibration is easy, i just put it down on a flat surface like the area next to my track pad on my Mac book and click calibrate, takes a split second. I did a trial run and was getting very high blue valeus for anything lower than 5o IRE then realized i was boosting gamma in my lumagen so i need to make another pass , too lazy to do it right now. But HCFR is very cool, like your barcos i wish the Marquees had more steps in the adjustments for G2 and drive. I wonder if the newer software versions have that fine control. But once i get the PJ levels set as best I can, on to the color gamut controls of the lumagen for super fine tuning.

Athanasios

WTS · Joined: 08 Mar 2006 Posts: 1276 Location: Calgary

Kal,

Don't forget that with either Moome's or Kim's gamma circuits, when you increase the gamma you're also increasing the contrast by a large amount. Are you compensating for this? Your contrast is actually alot higher than you think if you have the gamma on Moome's unit set about half way. Actually I have modified the unit I have to bypass the gamma circuit completely at the moment.

I was using 10% windows, I used the AVS BR disc.

**kal** · Posted: Mon Apr 21, 2008 3:27 pm Post subject:

garyfritz · Joined: 08 Apr 2006 Posts: 12088 Location: Fort Collins, CO

The worrisome thing about the gamma circuits is that you can't just counterbalance it by lowering contrast. They're increasing the Vpp in the video signal, and there is a limit (different on every model of projector) of how much the video input circuits can take without overdriving. If the input circuit saturates, lowering the contrast won't help. Even if you're not showing artifacts of overdrive (in my projectors the colors "bleed" to the right of intense areas), you're not working in the designed range for the circuit and I suspect that could cause problems.

That may be the biggest advantage of the voltage-output adjustment in Moome's new box, assuming it lets you *lower* the output voltage enough to counteract the gamma boost.

WTS · Joined: 08 Mar 2006 Posts: 1276 Location: Calgary

HI Gary,

I did scope the output of a prototype version and if I remember correctly I do beleive that at full gamma there was just barely enough cut to get it close enough to.7vpp to be good. You still need a scope to set it up correctly, don't just rely on "if I turn this one up this many turns then I should turn this one down that many turns" kind of setup.

WTS · Joined: 08 Mar 2006 Posts: 1276 Location: Calgary

Here's another HCFR file I did last night. I took the HCFR probe out of the plastic case it was in because the holes for the sensor weren't drilled directly over the sensors so it might have been some internal reflected light scatter, not sure if it really made much difference.

**kal** · Posted: Tue Apr 22, 2008 12:10 am Post subject:

Looks pretty good Walter. Your gamma's a tiny bit lower now (2.37 average instead of 2.46). Do you notice any extra shadow detail?
I still don't understand what your Y (luminance) measurements mean.... according to your numbers you're getting 1.897 ftL at 100 IRE which is definitely not right!

Kal

WTS · Joined: 08 Mar 2006 Posts: 1276 Location: Calgary

Hi Kal,

Never really had any time to watch much last night after I finished playing with it, had to watch Calgary kick San Jose first before I played with it.

I have no idea why the luminance is so low a reading. Unless your contrast is in torch mode and mine is in flashlight mode, but mine has plenty of punch to it. I guess I'll have to ask the HCFR guys why that is.

Some of the other reading don't match either, if you look at the RGB levels graph and the RGB levels on the Free measures they don't match either. When I do the greyscale setup using the continuos mode the RGB levels are basically on top of each other from 20 to 100, sometimes you only see one colour because the other 2 are buried under it it's so close. But you look at the RGB levels graph and it shows that they're off mostly the blue, which isn't really the case. So now I go well which one is correct, I say the continous measure is correct because it's realtime compared to a snapshot, but that's my guess.

Well goit the Moome board back today so I'll play with and set the gamma up, I think you said your's was at about half, that's a good enough starting point. And of course I'll scope it to set the 100ire level to 0.7vpp after I set the gamma up. Then I'll run another greyscale setup.

timf · Posted: Tue Apr 22, 2008 11:37 pm Post subject:

Kal,

Are you far off posting that sticky? Busting my a$$ to give this a shot Smile

**kal** · Posted: Wed Apr 23, 2008 12:25 am Post subject:

I was working on it again today, wordsmithing a lot. I'm working on it again tonight. I'd really like to get it done in the next 2-3 days to get it out of the way.

Kal

timf · Posted: Wed Apr 23, 2008 12:28 am Post subject:

You are a true legend Wink