I've noticed a couple of things over the past few days of calibrating that have me worried. Using my Chroma5 on a Pioneer 111FD, looking at an HDMI input displaying Tom Huffman's free patterns. Display and meter are both warmed up in all cases.

The first problem is that for the 40%, 50%, and 60% intensity windows I will often see the blue channel "drop out" on the CalMAN (v3.3) curves and bar charts. Doesn't matter if it's the grayscale curve or the RGB tracking bars, etc. I will often have to re-read these stimulus windows one or more times to get a reading consistent with the points on either side.

The second thing is that I seem to get progressively more unstable readings as I continue to take them (across the range). For example, I was just doing 9 point gamma and was on the 70% intensity point. Now, after I was done with the first part of my cal Thursday (grayscale + RGB) I was reading a gamma of 2.18 at 70%. Without having made any additional adjustments, the first time I read it tonight it was 3.34! And it just bounced around and was very unstable the whole time. Is this normal? Is it possible I didn't have the Chroma5 warmed up enough (it was on the display for at least 30 minutes)? What are the symptoms of a bad meter?

With the first issue, I have that same problem as well. Sometimes one of the channels “drops out” as you put it, and has to be re-read for a correct reading. I've had two Chroma 5s and they both did this, it seems to be an issue with the sensor design itself and some display types. (tended to happen with CRTs and Plasmas for me)


For the second issue, Pioneer plasmas have an annoying habit of automatically dimming the display if they don't detect any picture changes for a certain length of time. I'm not sure how long this is, or how the detection works.

Of course, this is a huge annoyance when trying to calibrate the display with static test patterns, especially ones where only a small spot in the centre changes, which may or may not be enough to trigger it to go back to full brightness.

Could that be the problem?

With the first issue, I have that same problem as well. Sometimes one of the channels “drops out” as you put it, and has to be re-read for a correct reading. I've had two Chroma 5s and they both did this, it seems to be an issue with the sensor design itself and some display types. (tended to happen with CRTs and Plasmas for me)


For the second issue, Pioneer plasmas have an annoying habit of automatically dimming the display if they don't detect any picture changes for a certain length of time. I'm not sure how long this is, or how the detection works.

Of course, this is a huge annoyance when trying to calibrate the display with static test patterns, especially ones where only a small spot in the centre changes, which may or may not be enough to trigger it to go back to full brightness.

Could that be the problem?

I'm not sure Andrew, or at least I don't think so. The fL value doesn't seem to change when this happens. How repeatable were your measurements with your Chroma5s?

I can live with having to remeasure from a dropout as long as it doesn't happen too often. But as to the second problem, it is getting a little annoying. Do I believe the first measurement? The second? The 12th?

I didn't have the Chroma5 warmed up enough (it was on the display for at least 30 minutes)? What are the symptoms of a bad meter?

The C5 is temperature compensated.

http://www.controlcal.com/forum/showthread.php?t=378

My tremendous thanks to Derek and the rest of the SpectraCal team for doing their best to help identify and provide mitigation for this problem (which turns out to be a real problem!). This may help others.

What we have found is not as much as a "real problem" as Tony puts it but just a odd way the C5 works on some Plasmas not all.

The Chroma5 has a sync sensor so when reading off a direct view CRT it can time the readings so the other sensors get the same amount of exposure time. Which with the C5 is a bit tricky because the C5 has it's sensors arranged in two rows and those two rows could be on different scan lines on the CRT.

Anyhow when reading from a Plasma you don't need the sync because of how Plasma works but when turning the sync sensor off at some point usually 40-60% stim the C5 really gets confused because a Plasma does energize the phosphor just not the same way as a scan line CRT but as pulse width modulation kind of like Morris code. It's at this point the C5 thinks it's reading a CRT and wants to try and sync even with the sync sensor off and is when it can’t sync you get odd results.

So the current work around if you are getting erratic readings that being the RGB’s are jumping around a lot for no good reason is to tell CalMAN the display type is a direct view CRT and just ignore the sync step. The only difference to CalMAN from Plasma vs CRT is we turn on/off the sync sensor.

So the current work around if you are getting erratic readings that being the RGB’s are jumping around a lot for no good reason is to tell CalMAN the display type is a direct view CRT and just ignore the sync step. The only difference to CalMAN from Plasma vs CRT is we turn on/off the sync sensor.

It's not clear from this what's fixing the problem.
Are you saying the C5 + CalMAN can be in three states?

Unsynced.
Synced.
Synced but not setup.

And that being in state 3 will stop the extended (and sometimes failed) reads that happen starting around 40%?

It's not clear from this what's fixing the problem.
Are you saying the C5 + CalMAN can be in three states?

Unsynced.
Synced.
Synced but not setup.

And that being in state 3 will stop the extended (and sometimes failed) reads that happen starting around 40%?

For the most part yes. For Plasma's that cause the C5 is be erratic using CRT direct view tells CalMAN to turn the sync sensor on but we don't require a sync to happen to be able to read.

For the most part yes. For Plasma's that cause the C5 is be erratic using CRT direct view tells CalMAN to turn the sync sensor on but we don't require a sync to happen to be able to read.

Well I'm happy to report that CRT D-view fixes the delayed read problem and seems to greatly reduce jitter in repeated mode but if you try to take readings without a sync you get a pop-up that says you must sync.

Thanks Derek. I was about to ask if I could return the C5 I just bought, but I tried what you said and it does fix the problems. I'm a happy camper again. :)

Thanks Derek. I was about to ask if I could return the C5 I just bought, but I tried what you said and it does fix the problems. I'm a happy camper again. :)

In CalMAN v3.41 we have changed the Plasma mode to use auto-sync but not require sync as a step. So this should be a good solution for everyone.

Derek, is 3.41 stable enough to replace 3.4? Will I lose any of my custom Layouts or anything if I install this version?

In CalMAN v3.41 we have changed the Plasma mode to use auto-sync but not require sync as a step. So this should be a good solution for everyone.

Thanks for all this info Derek! This will be a great time saver when I start using my Chroma 5, which should be arriving today. I downloaded CalMAN yesterday from the Spectracal site and it was version 3.4(0?). Is there a place to get version 3.41, or am I using the most current version of the software (with the fix in it)?

I've noticed a couple of things over the past few days of calibrating that have me worried. Using my Chroma5 on a Pioneer 111FD, looking at an HDMI input displaying Tom Huffman's free patterns. Display and meter are both warmed up in all cases...

Thanks so much for initating this thread, tonyptony! Great info here.

In CalMAN v3.41 we have changed the Plasma mode to use auto-sync but not require sync as a step.

This is in yet to be released code?

Thanks for all this info Derek! This will be a great time saver when I start using my Chroma 5, which should be arriving today. I downloaded CalMAN yesterday from the Spectracal site and it was version 3.4(0?). Is there a place to get version 3.41, or am I using the most current version of the software (with the fix in it)?

Gerianne, 3.4(0) is the current official release, I think. 3.41 is the currently available beta release. Go to the Other Downloads section

You're welcome! :)

Gerianne, 3.4(0) is the current official release, I think. 3.41 is the currently available beta release. Go to the Other Downloads section

You're welcome! :)

Finally got to take a look at the Other Downloads section and found the beta release. Appreciate the help once again!