CurtPalme.com Home Theater Forum

[Francisco]

I've a question about my Gamma curve.
I always calibrated my Barco's myself with HFCR and i1 pro. RGB levels are all good for now, but gamma goes down linear from 2.5 to 1.8 on 100IRE
Now I didn't defocus blue yet, tubes P19 LUG simu grade are good as (200hr) new. I can however adjust gamma on the Barco or Crystalio II or moome (IFB-HD v3). I'm not so familiar with adjusting gamma to the right 2.2 point. It always was spot on with my other Barco's as far as I can remember.
How do you guys get the right 2.2 all the way from 10 till 100 IRE? and what should I adjust Barco, Crystalio or moome?
Pics

[stridsvognen]

I would think this is messed up somewhere in your digital chain, so you might have level 0-255 or 16-235, set wrong in the moome Crystalio or player.

Try play with those levels, and see to that contrast and brightness settings are neutral in all the digital chain.

I try always to run my digital chain with no manipulation to the signal, and do all the calibration in the CRT.

Might try run 16-235 all the way to the moome card and run that at 0-255, and see what that will do to your gamma curve.

Ohh and dont use the gamma boost in the moome card, set that to 0.

[ElTopo]

http://www.curtpalme.com/forum/download.php?id=12085

My 909 calibrated with the auto-cal feature of Calman and Lumagen.


ElTopo

[stridsvognen]

I would never run a auto calibrate on my CRT using heavy digital correction to help correcting what i messed up in the signal path, its hard to get it right without, but its possible, if you can just live with a small blue bump. I think its worth all the time it takes, as i think using the Lumagen CMS on a CRT will give it the image the negatives from doth CRT and Digital. Just my crazy opinion.

If you run 1080P 60hz and not needing the timing adjustments, it will look best not having the Lumagen in the chain at all.( Depending your source) At least for high quality Blu Ray.

I still miss to see a video processor who dont mess up the signal some, even just passing it.

[ElTopo]

The measurements were done with an OCT-1000.

So i don't think the pre and post values are wrong.

The picture looked pretty stunning without doing further calibration.

[ElTopo]

http://catalogs.infocommiq.com/AVCat/images/documents/pdfs/OTC1000-CMflyer.pdf

[Francisco]

checked the whole chain, and all was set to 16-235. Tried with moome set to 0-255 then I couldn't see BTB and had to raise brightness to have proper low level ire. It doesn't do anything to gamma unfortunate stayed the same.

Also my ftl is low at 7 ftl on 100ire. I tried to adjust gamma with Crystalio on every step from 10 to 100ire but I don't get it right it still drops from 2.5gamma 10ire to 1.7gamma 100ire

Changing gamma on moome will give better starting point on low ire 2.2 at 10ire but then still drops down in higher levels.

I don't get it right and I don't understand why I have low ftl readings with new tubes, any thoughts are welcome

[hansilili]

[Nashou66]

How big is your screen? 7ftl doesnt sound too bad if you have a large screen, say over 10ft wide.

Nashou

[Francisco]

I use DVE HD essentials with windowed ire pictures as described in calibration for dummies

Screen is 9.1feet 280cm wide, oh and yesterday I used my eye-one display2 meter it only reads 6-7ftl
I will dig into it some more.

[stridsvognen]

How do your gamma curve respond if you adjust your contrast down, and brightness up on the Projector.?

[Nashou66]

The 7 Ftl Sounds about right to me. A single 9500 had a 5 ftl on a 12 foot screen with a gain of 1.2 here in my house.

Nashou

[ElTopo]

7-9 ftl are realistic for your screen width.

Got more or less the same for my 909 with new tubes.

[Francisco]

Ok for 6-7 ftl, I also didn't feel like missing too much light. But the strange behavior of gamma bothers me. Tonight I will change some boards and also try PC input to see if something changes.

[Francisco]

Okay tried original non modified stock Barco boards but still same behavior. Some more testing tommorow....

[redfox001]

I once had a Marquee with fast phosphor on green and the gamma on green was like yours until I raised the scanning frequency to 72 Hz. Perhaps something to try?

I had to run at 120 Hz to get the same output as 60 Hz on a normal tube. In the end I corrected the gamma with a scaler too and that was a fine solution.

[stridsvognen]

Here is a calibration file from a standard Marquee, with no digital correction.

[Francisco]

Tested gamma curve on my test chassis with stock boards original LUG's and no colored C-elements, result flat 2.2 gamma from 10 to 100IRE.....

So I thought maybe the modified video chain disturbed gamma and changed modified boards for original in my main viewing projector. Unfortunate (but fortunate) same disturbed gamma curve. So it must be somewhere else in the projector. By the way, I kept same source on both projectors. PS3 > moome ext. V3 > port5 Barco.

Which boards are responsible for gamma in the Barco?

[redfox001]

Is there not something to make the focus sharper on your Eisemann tubes? I am thinking that perhaps you could try the tray with the focus or did Eisemann mod something on the tubes to make them sharper? I am thinking that because my blue was like yours and slicht defocus made it go straigther. I would at least expect your blue to be worse than the other two ??? Hope this helps. Or else the type of phosphor these tubes use?

[redfox001]

Just another possibility. The emission of the filament? Checking the 6V?

The gamma correction is on the RGB driver but green is not corrected as far as I know.