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I'm looking at having my new Samsung LED/DLP RPTV (HL-67A750) calibrated. One ISF calibrator uses the Sencor/Colorpro approach where he places the sensors on the screen while the other uses the Photo Research device which is stand mounted directly in front of the TV. Which is the better method or will they both give the same results?


I also have a ceiling mounted DLP projector. Should I assume the Photo Research stand mounted technique is the only way to calibrate that set?


Jack
 

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Quote:
Originally Posted by JackB /forum/post/14330102


I'm looking at having my new Samsung LED/DLP RPTV (HL-67A750) calibrated. One ISF calibrator uses the Sencor/Colorpro approach where he places the sensors on the screen while the other uses the Photo Research device which is stand mounted directly in front of the TV. Which is the better method or will they both give the same results?


I also have a ceiling mounted DLP projector. Should I assume the Photo Research stand mounted technique is the only way to calibrate that set?

The Photo Research is definitely the more accurate device, though its low-light performance is not great. Both devices are placed on a tripod, so it makes no difference to aiming.
 

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Quote:
Originally Posted by JackB /forum/post/14330102


I'm looking at having my new Samsung LED/DLP RPTV (HL-67A750) calibrated. One ISF calibrator uses the Sencor/Colorpro approach where he places the sensors on the screen while the other uses the Photo Research device which is stand mounted directly in front of the TV. Which is the better method or will they both give the same results?


I also have a ceiling mounted DLP projector. Should I assume the Photo Research stand mounted technique is the only way to calibrate that set?


Jack

Spectroradiometers like the Photo Research units and the Konica-Minolta CS-200 chroma meter are the gold standard in reasonably portable meters for measuring all types of video displays. Filter-based instruments like the Sencore "pucks" or the tripod-mounted OTC-1000 (many other brands use filters also) are more difficult to optimize for different types of displays - in fact some "pucks" are optimized for a specific display type and will be much less accurate if used with a different type of display. CRTs and plasmas have light from phosphors, LCD panels have fluorescent backlights or LED backlights (very different color spectrums for each), DLP & LCoS & LCD projection systems use projection lamps. All 3 have different light spectra that need to be measured accurately the PR and CS-200 units measure all those display types accurately. Other solutions require some compromises like multiple pucks or software "correction" for the type of display.
 

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Doug, isn't the CS-200 a filter-based tristimulus device also?

Quote:
Originally Posted by Doug Blackburn /forum/post/14334687


Spectroradiometers like the Photo Research units and the Konica-Minolta CS-200 chroma meter are the gold standard in reasonably portable meters for measuring all types of video displays. Filter-based instruments like the Sencore "pucks" or the tripod-mounted OTC-1000 (many other brands use filters also) are more difficult to optimize for different types of displays - in fact some "pucks" are optimized for a specific display type and will be much less accurate if used with a different type of display. CRTs and plasmas have light from phosphors, LCD panels have fluorescent backlights or LED backlights (very different color spectrums for each), DLP & LCoS & LCD projection systems use projection lamps. All 3 have different light spectra that need to be measured accurately the PR and CS-200 units measure all those display types accurately. Other solutions require some compromises like multiple pucks or software "correction" for the type of display.
 

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Tom


yes it is.....one would think any calibrator being derogatory to tristimulus filter based sensors on principle would also call the CS-200 a 'puck' or a 'pod' . It uses more filters than just three to form the tristimulus filtering, same as a Spyder does (but with 40 filters not 8) it takes the difference between optical filters to create a bandpass filter from which the tristimulus filter is created - obviously requiring accurate calibration - but it is not capable of sampling a spectrum like a spectroradiometer. In fact the user calibration is nothing more than an xy offset reading - the exact same thing that simple software "correction" would do!


It just has very good optic/filter design and is designed to be frequently recalibrated so one can make it the portable instrument always calibrated to the lab spectroradiometer for your light sources. Having a lens with a selectable measuring angle is a useless feature for home theater, that is only needed to measure very small color features.


So it is in fact a colorimeter - just not a conventional colorimeter like what comes in a pod without a lens with only a factory calibration. KM would be foolish to even try to market it as a spectroradiometer - so not sure why some calibrators have chosen to do so. If they do so they must also call the Spyder pod a spectroradiometer!
 

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Quote:
Originally Posted by JackB /forum/post/14330102


I'm looking at having my new Samsung LED/DLP RPTV (HL-67A750) calibrated. One ISF calibrator uses the Sencor/Colorpro approach where he places the sensors on the screen while the other uses the Photo Research device which is stand mounted directly in front of the TV. Which is the better method or will they both give the same results?


I also have a ceiling mounted DLP projector. Should I assume the Photo Research stand mounted technique is the only way to calibrate that set?


Jack

Bottom line to your original question, if using a knowledgable person with both types of devices, a RPTV (and certainly not an LED/DLP) cannot be tweaked to its full potential with a CP5000 device vs a SpectroRadiometer no matter what someone might try to tell you. Of course, a monkey cannot calibrate your set with a SepctroRadiometer as well as an ISF tech with a CP5000.
 

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Quote:
Originally Posted by BeachComber /forum/post/14336965


Bottom line to your original question, if using a knowledgable person with both types of devices, a RPTV (and certainly not an LED/DLP) cannot be tweaked to its full potential with a CP5000 device vs a SpectroRadiometer no matter what someone might try to tell you. Of course, a monkey cannot calibrate your set with a SepctroRadiometer as well as an ISF tech with a CP5000.

There is a variable that accounts for why spectroradiometers perform better and more consistently across a broad range of devices in a way that tristimulus devices do less well, but I don't think that it is display technology. For example, I have 2 LCD monitors I use for testing purposes. On one of the them the tristimulus probes track the i1Pro results very closely and other the other they deviate considerably. Clearly one of the LCDs (but not the other) emits some type of radiation that plays havoc with the colorimeter's accuracy.
 

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Discussion Starter #8
Thank you guys! Very interesting discussion. I think I will go with the ISF'r with the Photo Research. I have a little convincing to do with my wife as she feels the Samsung looks pretty good as is. This will be expensive as I have to add the calibration for the SharpVision 12000MKII, a new bulb for the Sharp, and my new living room sound system needs the fine hands and ears of a sound calibrator. Looks like a $1,200+ problem for me.


BTW, since the two televisions would be in the same trip should I ask for a package discount on the calibration? He's asking $400 for the Samsung.


Jack
 

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Greetings


You can always ask ... and if its the difference between all or nothing ... well ...


75% of something is better than all of nothing.



regards
 

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If this is about selecting a calibrator - owning a PR650 (or not) and discounting next display (or not) - is likely not the best criteria for selection. Pods are inaccurate because little time is spent on factory calibration and have little facility for field calibration - but someone can have the most expensive sensor in the world - and it does little good if it is intended for lab use rather than field use or has never been (re)calibrated.


Just hang out here and in the display forums and figure out who you think knows calibration and that you would welcome in your home all day.


At the price those Sharps are closing out at - you can't go wrong though no matter what you pay for calibration - think about the people that paid 10x that for factory fresh display few years ago. You could argue you should pay $11K for calibration as those people thought it was worth it when they paid that much overall!
 

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Quote:
Originally Posted by JackB /forum/post/14338079


Thank you guys! Very interesting discussion. I think I will go with the ISF'r with the Photo Research. I have a little convincing to do with my wife as she feels the Samsung looks pretty good as is. This will be expensive as I have to add the calibration for the SharpVision 12000MKII, a new bulb for the Sharp, and my new living room sound system needs the fine hands and ears of a sound calibrator. Looks like a $1,200+ problem for me.


BTW, since the two televisions would be in the same trip should I ask for a package discount on the calibration? He's asking $400 for the Samsung.


Jack

I offer both audio and video calibration and have PR-670 that was recently calibrated. My gear for both of these tasks is very high quality and the testimonials supporting this quality are many. I will return to your region in September if you are interested take a look at www.accucalhd.com/pricing.htm and http://www.accucalhd.com/service-testimonials.htm for reviews of my work in both areas. The PR-670 that I use is better than a PR-655 or PR-650.
 

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Quote:
Originally Posted by TomHuffman /forum/post/14334738


Doug, isn't the CS-200 a filter-based tristimulus device also?

Yes, which is why I used the "chroma meter" designation to separate it from spectroradiometers. It's in a far different range of performance than more typical filter-based meters. And it reads low luminance levels better than most resonably portable meters - including spectroradiometers.
 

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The CS-200 is a very unique piece. It will allow for accurate spectral readings (if you pay the extra amount to Minolta).


Saying:
Quote:
The PR-670 that I use is better than a PR-655 or PR-650

is really going off the wall. There is NO APPLICATION in home theater where this could be shown to be be true (with the exception of low level light readings).


Regards



Gregg
 

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Quote:
Originally Posted by krasmuzik /forum/post/14335651


Tom


yes it is.....one would think any calibrator being derogatory to tristimulus filter based sensors..... KM would be foolish to even try to market it as a spectroradiometer - so not sure why some calibrators have chosen to do so. If they do so they must also call the Spyder pod a spectroradiometer!

I was not being derogatory about filter-based sensors - just stating the facts. I did not call he CS-200 a spectro radiometer... I called the Photo Research devices spectroratiometers and I called the CS-200 a Chroma Meter which is what Konica-Minolta calls it.
 

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Quote:
Originally Posted by Gregg Loewen /forum/post/14345475


The CS-200 is a very unique piece. It will allow for accurate spectral readings (if you pay the extra amount to Minolta).

I am confused about just what type of device this is. Here's how Minolta describes it:


*****************


There are two ways of determining luminance and chromaticity values for a light source.


A tristimulus type of instrument measures light sources with three sensors (red, green, blue) that have sensitivity similar to the sensitivity of human eyes to light. The filters used to reach this sensitivity have a limit in precision and thus the readings of tristimulus instruments can not be perfect on all kind of light sources. Best accuracy is reached when measuring light sources with a similar spectral distribution like that of the light source used for calibration of the instrument.


The second method, which is used by the CS-200, is to measure the spectral emittance of the light source and perform calculations using the spectral sensitivity characteristics (color-matching functions) corresponding to the sensitivity of human eye. By this method, the mis-matching of filters is avoided and thus the measurement results are much more precise.



***********************


This description implies that the CS-200 is a type of hybrid between tristmulus colorimeters and spectroradiomters.
 

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Quote:
Originally Posted by Gregg Loewen /forum/post/14345475


The CS-200 is a very unique piece. It will allow for accurate spectral readings (if you pay the extra amount to Minolta).


Saying:


is really going off the wall. There is NO APPLICATION in home theater where this could be shown to be be true (with the exception of low level light readings).


Regards



Gregg


You want to do a comparison and see if they get different readings on various displays with primaries, secondaries and white points. I would be happy to do it at CEDIA. This includes blue on front projectors.
 

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Quote:
Originally Posted by umr /forum/post/14345698


You want to do a comparison and see if they get different readings on various displays with primaries, secondaries and white points. I would be happy to do it at CEDIA. This includes blue on front projectors.

Gregg can speak for himself, but I would assume that a blue reading off a FP screen would qualify as the one exception he noted: low light level readings.


Assuming no screen gain, a 2.2 gamma, and 12 fL peak output, a 75% Rec. 709 blue pattern would offer a target of only 0.46 fL. The PR-655 is rated only down to 0.2 fL, so I doubt that a PR-650 would offer reliable results in this case.
 

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Quote:
Originally Posted by TomHuffman /forum/post/14345937


Gregg can speak for himself, but I would assume that a blue reading off a FP screen would qualify as the one exception he noted: low light level readings.


Assuming no screen gain, a 2.2 gamma, and 12 fL peak output, a 75% Rec. 709 blue pattern would offer a target of only 0.46 fL. The PR-655 is rated only down to 0.2 fL, so I doubt that a PR-650 would offer reliable results in this case.

Of course almost all other instruments will dramatically fail at blue on a typical front projector. I find the blue spectrum in general is also one of the most difficult. I would be very surprised if any other tool matches the readings of the PR-670 within +-0.003 xy for all display types and color readings unless it was something comparable like a CS-1000 or CS-2000.


I offered to do the same with Sencore last year, but they never came through. I offer Gregg the same opportunity to prove me wrong.
 

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Attached are three .jpg files which display the difference between an instrument with low bandwidth such as the i1Pro which has essentially the same spectral bandwidth and spectral resolution as the CS-200 Minolta instrument, a PR-650 which has 8nm bandwidth and 3.125 spectral resolution, and a Minolta CS-1000 which has 5nm spectral bandwidth and .9nm spectral resolution.


Where the user will see a major difference in performance between the various instruments is not confined simply to light level! The bandwidth is critical when attempting to measure displays which exhibit spikey spectral output which are typically found in LCD panels as well as Plasma displays. When you have a display which has spikes which lie closer together then the bandwidth of the instrument the data will contain errors as the peaks will overlap. The example shown is of a desktop computer LCD display which does not have peaks which are close enough together to cause a measurement error however there are many displays which do.


The PR-650 is rated to only 1.0 fL and will not even measure much below .8 fL before it returns a warning that the signal is too low to measure. The Minolta CS-1000 will measure to a bit lower then the PR-650 and the i1Pro will only provide reasonable accuracy to about 1.0 fL at best. You will find that pieces such as this and the CS-200 will have a very difficult time measuring new display technologies such as the soon to be released laser based RPTV displays from Mitsubishi and other LED backlight displays as the lack of bandwidth will create huge errors. The CS-200 will not even accurately measure a BVM-96 monitor which should be a piece of cake.


Many of the top reference analyzers are not able to measure to low enough light levels to perform a proper Grayscale calibration as you need to go significantly lower then 1.0 fL on most plasma panels and DLP projectors to align the bottom end of the display correctly.


 

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Here is are some examples with my PR-670.


The other thing to point out is the CS-200 lacks the attachments for eliminating room light (LA-670 on my PR) or a diffuser (CS-670 on my PR) to measure illuminance. These greatly improve the instruments flexibility in difficult situations allowing readings to be taken in less than ideal ambient light situations.


 
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