Home Theater Forum and Systems banner

1 - 20 of 28 Posts

·
Registered
Joined
·
9 Posts
Discussion Starter #1
I own Sony VPL-HW15 for about 3 years. I begin to have a white balance issue since my projector lamp at about 400 hours usage.

At a cinema mode I got a measurement on white balance on 6500K with average gamma at 2.2 (after calibration) when was new. After 400 hours of usage. The best result after calibration is 8000K for white balance and gamma at 1.5.

With a help of Lumagen and Cokin 85C filter. I calibrate to 6500K for white balance and gamma 1.97.
The problem is it due to projector lamp or others?
 

·
Plain ole user
Joined
·
11,121 Posts
It is unusual for the color temperature to go up that much. How many hours did you have on the lamp at the first calibration?
 

·
Registered
Joined
·
9 Posts
Discussion Starter #6
The first time I was calibrate my projector went I brought Spyder TV three years ago. The software use for calibration is ColorHCFR. At that time the lamp hours is less than 50. Second time calibrate when the lamp hours was 200 hours. White balance reading is close to 6500K.

The third time I calibrate when the lamp hours was 400. With a projector setting remain during second calibration. The reading for white balance is above 10000K. After I increase Red gain and bias to max and reduce Blue gain and bias to min. The reading for white balance is about 8000K.

I suspect is a meter giving an error reading. Next I brought Calman 4 and i1 Display Pro meter last years. I took the reading, and the result almost similar.

Next step, I try with varies Cokin filter to attach in front of projector lens and recalibrate. I end-up with 85C filter. At 80IRE the DeltaE is bellow 3 and the 30IRE DeltaE is between 5 to 10(I can’t recall the actual reading). Not bad, but the average gamma at 1.5. The picture looks wash-up and low contrast.
I am not happy with a picture quality vs. the cost for setup-up my home theatre room. Lately I brought LumagenMini to add on my system. At the same time my software upgrade to Calman 5 with 125point color gamut auto calibration.
 

·
Plain ole user
Joined
·
11,121 Posts
The original reading was likely off for some reason. Lamps don't increase in color temp as they age, just the opposite usually. That kind of difference would be be a very noticeable change.
 

·
Registered
Joined
·
178 Posts
Sorry, but I have to disagree with lcaillo on this: Typically UHP lamps decrease in red light output as they age this will increase the colour temperature as it tends to more blue/green.

You can be unlucky with lamps that drift quickly. It might still have a reasonable light output but calibration wise it is going to struggle as you have to cut the blue and green gains to match, which further reduces light output. Of course as has been said the meter could be at fault, but the i1 display Pro (D3) is a bit better than the old i1D2 as I understand it. Also you can send a D3 back for recalibration which you couldn't do with the D2.
 

·
Registered
Joined
·
9 Posts
Discussion Starter #11
What is the final decisions should I make?

I am thinking to send back i1 display Pro back to Spectracal for calibration and recalibrate the projector after meter return. If the measures result remain the same. Replace projector lamp. Is it the ideal?

If they any possibilities due to others problem like LCoS Panel?
 

·
Registered
Joined
·
178 Posts
The i1 display Pro can't be that old and unless it's been dropped or otherwise mistreated then I wouldn't expect it to need recalibrating. I know your location might mean a higher humidity zone than where I am, but IIRC it is supposed to be less susceptible to moisture compared to the old i1 D2.

How does it look to you? If it's that far out you should be able to tell.

While 400 hours seems a short time for a lamp, I had a lamp once that dimmed at around 550 hours and the red was getting lower and lower. If you think it's worth spending the money on a new lamp (and not a cheap knock off which may be no better than what you already have) then I'd try that route. There were some issues with Sony LCOS panels, but this was a very long time ago and was in rear projection TVs I believe.
 

·
Registered
Joined
·
9 Posts
Discussion Starter #13
Yes KelvinS1965, I agree with you. The meter should work well. The grayscale and color look good on the screen after calibrate by adding LumagenMini Video Processor. Accept the dark scene look don’t dark enough. The gamma at 1.97. Anything above 1.97, loss on black detail.
 

·
Registered
Joined
·
178 Posts
A gamma of less than 2 is pretty low, though I tweak my Mini3D at 5% and 1% so that the gamma drops to about 2.1/2.0 at this % but it is flat at 2.22 above 15% or so. If your room has light walls/ceiling then you may have to run this low anyway, but if it's a true 'bat cave' then you should be able to run higher, but only if your projector's on/off contrast can support a higher gamma.

Perhaps Michael would know better than I, but I believe that to run a gamma of 2.2 you need an on/off contrast of around 30,000:1 (maybe higher) which is above what your projector can do by some margin as I imagine it's native contrast is around the 5,000-6,000:1 level. It might be worth trying a BT1886 gamma setting as this takes into account the true on/off contrast of the display (but can be difficult to measure the on/off on very high contrast displays).
 

·
Premium Member
Joined
·
519 Posts
Perhaps Michael would know better than I, but I believe that to run a gamma of 2.2 you need an on/off contrast of around 30,000:1 (maybe higher) which is above what your projector can do by some margin as I imagine it's native contrast is around the 5,000-6,000:1 level. It might be worth trying a BT1886 gamma setting as this takes into account the true on/off contrast of the display (but can be difficult to measure the on/off on very high contrast displays).
If i remember correctly only Kuro could measure 2.2 gamma in low scale (from 2-10 IRE) and with a luminosity peak at about 170 nits. Therefore, i would not expect any projector to achieve an accurate gamma (2.2 or 2.4) in low scale with 40 or 50 nits of light.
 

·
Registered
Joined
·
178 Posts
I'm not 100% sure if I understand what you mean Yiannis about 'in low scale'. I recently re did my greyscale and gamma on my X35 using a D3 (enhanced) and got a flat 2.2 gamma until I deliberately lowered the 10 and 5% points towards 2.1 (to help with shadow detail since my room isn't ideal yet).

 

·
Premium Member
Joined
·
519 Posts
I'm not 100% sure if I understand what you mean Yiannis about 'in low scale'. I recently re did my greyscale and gamma on my X35 using a D3 (enhanced) and got a flat 2.2 gamma until I deliberately lowered the 10 and 5% points towards 2.1 (to help with shadow detail since my room isn't ideal yet).

Hello Kelvin!

By ''low scale'' i mean the information below 10 IRE. The type to figure out luminosity at various gamma points is the following:

IRE^GAMMA POINT X LUMINOSITY IN 100 IRE.

1 IRE = 0,01
2 ΙΡΕ = 0,02

and so on. For example:

Let's say that our peak white in 100% pattern is 50 nits and trying to spot a 2.2 gamma point below 10 IRE.

0,03^2.2x50= 0,02 nits.

So, in order to have a gamma point 2.2 at 3%, we need that our pj can achieve 0,02 nits. If not, our gamma point will be lighter.

0,02^2.2x50= 0,009 nits.

As you can see, the light does not be defined analogically in the various IRE but algorithmically, making very hard for most projectors to keep up the pace. Therefore, the majority of the units present the so called ''veil'' in low light scenes. Practically, in these kind of scenes our projectors output a lighter gamma point like 1.9-1.8 or lower.
 

·
Registered
Joined
·
178 Posts
Ah I get what you mean (should have read your earlier post more carefully :)). One method I have used to adjust the very low end is to create an offset in Chromapure so that I can read directly from the projector. This gives more light to play with but even then I can only measure 10% and 5% in Chromapure since it doesn't measure below this. I can measure RGB in real time and put up a 1,2,3 or 4% pattern if I wish but I can only adjust my Lumagen to one of these points (parametric greyscale adjustment can be moved from 0.5 to 100.0 in 0.5 steps).

As you say though the light output is very low at these levels and most projectors will give a 'veil' in low light scenes, which is why I have a preference for JVC projectors: Even these aren't perfect though, but they are pretty good especially in a long throw, minimum iris set up like mine which maximises the available contrast. Until I build a dedicated room I won't even get the best out my X35 let alone something better, but some room improvements in the short term might help a bit...Id really like an X95 in a total black cave lined with black velvet, but that isn't happening anytime soon. :)

Anyway, enough rambling: I've found a good way to be happy with your display: Focus on some new speakers or subwoofer as I'm doing. :D I'm off to hear some 15 and 18" subs with 3000 watt amps on Sunday. They also have a custom inroom setup with 8 x 18" speakers and 12000 watts of amplification. :unbelievable: Funny that they have an X35 in this (totally black room) and it looks like a totally different projector to mine because of the better room.:rubeyes:
 

·
Premium Member
Joined
·
519 Posts
Ah I get what you mean (should have read your earlier post more carefully :)). One method I have used to adjust the very low end is to create an offset in Chromapure so that I can read directly from the projector. This gives more light to play with but even then I can only measure 10% and 5% in Chromapure since it doesn't measure below this. I can measure RGB in real time and put up a 1,2,3 or 4% pattern if I wish but I can only adjust my Lumagen to one of these points (parametric greyscale adjustment can be moved from 0.5 to 100.0 in 0.5 steps).
I see!!

To be honest, i don't like to measure anything off the lens, because to achieve an actual reading that has practical value i need to do so only in a ''bat cave'' (no reflections, no gamma shifting). If i cut off from the equation my actual room enviromental conditions (light brown ceiling, dark yellow wall) measuring directly off the lens, my adjustment would appear wrong in actual viewing.

What do you think?
 

·
Registered
Joined
·
178 Posts
Usually you would be correct regarding measuring off the lens not taking the screen/room into account. However, with Chromapure you can create an offset:

1. You take 100% (or 75%) white, red, green, blue, yellow, cyan & magenta measurements off the screen. This is the 'reference' meter.

2. You take the same readings directly from the lens and Chromapure creats an offset. This is the 'field' meter.

This means that you can take all the measurements directly from the lens using the 'field meter' so that you get more light to play with which helps the sensor especially at low % readings. The offset takes the room and screen effects into account.

I don't know if other calibration software can do this, but it's a useful feature. However my D3 Enhanced measures pretty well off the screen anyway.

Also, as my screen (and room) is pretty neutral I can just change a setting in Chromapure and measure directly from the projector lens without creating the offset and the results are very, very close compared to measuring off the screen. If you had an exotic screen or perhaps red walls then you would have to use the offset method.

That we are even discussing how hard measuring at low % is then at least it shows that projector's black levels are getting really good these days.
 
1 - 20 of 28 Posts
Top