I had my projector ISF calibrated today, had a question needing answered. Can an ISF technician please tell me whether or not auto iris should have been engaged when calibrating a projector? I am a little confused on this.

greetings

I do it with the auto off ...

Auto does wonders to the gamma. (makes it all around crappy)

Then I let the client decide if they want it on. I doubt the AI of the IRIS control is the actual film maker making decisions to darken the image even more than in the original material.

regards

Hmm, well, I thought so too, but my calibrator calibrated it off. I noticed now that the image doesn't have that inky black that I was used to, although I think it looks better overall. Just wondering if it would do any harm to engage the iris even though he calibrated it being off.

Greetings

Grayscale will more or less stay the same, but wave good bye to good gamma.

Either you want an accurate image ... or you don't.

Regards

So, with auto iris engaged after an ISF cal, the gamma goes out the window? What if the auto iris was used during the cal, gamma still out the window? Or not?

If you're talking about a Sony SXRD, I agree with Michael for the most part and do the bulk of calibration with the auto iris off. However, I do engage it at the end and make some very small tweaks with it on. Usually turning it on will have a VERY small impact on grayscale at the low end so I might take the blue cut up by a notch. I also usually do a tweak to strengthen the blacks and reduce the clayface effect that it can cause. Those last two tweaks only take effect when it is engaged, so it does not compromise accuracy when it is turned off. It does destroy the gamma, but it does so in different ways depending on if you use window patterns or full fields. This along with knowing how it works suggests to me that impact on the gamma curve is program dependent and the measurements would show the worst case scenario for gamma change. Under normal program conditions the change will be anywhere from nothing up to the poor results that the measurements show. Overall I think the tradeoff is often worth it to have it on, but it is subjective. Do you want a higher contrast ratio or better gamma?
Yes, gamma is destroyed (more or less, as I said above) whether auto iris is engaged during the calibration or not.

So, with auto iris engaged after an ISF cal, the gamma goes out the window? What if the auto iris was used during the cal, gamma still out the window? Or not?

Well, if the DI is engaged, then a dynamic gamma algorithms is also being employed, so gamma becomes a moving target basically, and will change all the time depending on APL. DI is a good compromise if you're chasing better contrast ratios, and like all things in imaging there are always compromises. It's a choice the user has to make based on what they care about most.

Guys, I will bite my tongue here, but needless to say, I am very disappointed at my ISF performed recently. I waited a looooong time and agonized whether to do it because I wasn't sure if it was worth the money. I've read a lot on this forum, but don't have the experience or expertise really to do it right. So, after squeezing what I thought was every bit of performance I could without scientific measurements, I broke down and paid to have it done. I don't want to say who it was right now, because I want to have him come back ( he needs to at this point ) and make it right. However, this one thing has led me to question other aspects of his calibration and technique............really trying not to say too much at this point. Sad thing is, it was someone who recommended him on this forum.......

Scopeboy,

From what I read above, it does not sound like your calibrator was out of line. Of course, if you are unhappy with the results, the first step is to contact them and discuss it directly. There are generally factors when onsite that may have played a part regarding why the calibrator did what he did. Keep us posted as to how you make out.

Good Pictures! :)

Dave

Without mentioning his name, let me tell you guys what happened yesterday that led to this post.

He only calibrated using Digital Video Essentals HDdvd on a Toshiba A30. No calibration was done using the Vip V22 for high def, or the PS3 for bluray. Things didn't start so smoothly. He spent almost 3 hours watching his Sencore readings spike and drop drastically and couldn't figure out what was going on............I sat there watching over his shoulder every minute of the calibration, so I can confirm what I saw. Finally, after swearing, and clearly frustrated at what he was witnessing not being able to get an accurate readings from one second to the next. He got up out of the chair and walked up to the screen to fiddle with the sensor on the tripod. Turns out he hadn't calibrated it for darkness prior to starting the readings..............basically he arrived at 1:00, and really didn't start calibrating till almost 3:45. I am not exaggerating here when I say that once we identified that the sensor hadn't been adjusted for black, the greyscale was able to get dialed in within 10 minutes. Not sure how far off my projector was at this point because of the previous excersise. WE did finally get greyscale tracked, however, at the lower IRE, he didn't really want to fiddle with getting it any better. In his words, "not much information in the video world is displayed down in that area of the picture" He made no adjustments with the Gamma controls beyond what was already given as a preset of "Cinema" He then looked at my colors and said that they were pretty much spot on, thus not needing any real adjustment.............no adjustments were made at this time. That concluded the calibration. I was surprised. When I put on my AVC HD bluray disc I burned using the files provided on AVS, he scoffed and said that "thumbnails" aren't a good way to calibrate. He said he would rather use an acutal disc and was eagerly awaiting the DVE bluray disc to arrive. I told him that I burned this off the AVS forum. We never even discussed the PS3 in terms of a source device and the settings needed checking before calibration............I feel stupid for not saying anything at the time. I'm sure I am missing some information, but that is a good start to what transpired on Sunday.

Any tips on where to go from here? I am clearly frustrated at what I perceived in terms of what ISF meant. Perhaps my expecations were too high to begin with?

Scopeboy,

What you are describing is a very basic single input calibration, if this is what the calibrator stated he would do, then he may have been fully justified with what he provided. That said, it is important, when fully calibrating a system, to look at all sources involved and ensure that they are setup properly. The PS3 has many adjustments on it for both gaming and BD playback, these should have been looked at in order to ensure that the particular source was setup properly.

Please keep in mind that the calibrator may have only quoted you for a single input calibration, in which case, this may not have been included in his pricing. Most reputable calibrators will either include all sources in their calibration fee, or provide a list of pricing for additional sources. This is important as calibrating the display is only one part to optimizing system performance.

I would suggest contacting the calibrator and letting him know your frustration with the situation - this could prove a quick resolution to your concerns.

Good Pictures! :)

Dave

Thanks for chiming in David. I sent him an email, haven't been able to talk to him yet, sure he is out in the field. I hope to hear from him on this because I believe he will want to make things right. It just seems that several things were overlooked. I wanted a profile given to me at the time of calibration, but he said he would give me a hard copy in a few days. I believe he needs to come back again to look things over. I'm sure after looking at the calibrated image for about 2 hours today that something is amiss..................I just didn't feel comfortable after the goof, I would imagine a good ISF tech would have recognized this problem long before 3 hours lapsed...............don't you think? His competence was in question to me at that point.

Yes, a good calibrator normally WOULD have known about taking dark readings and how to do them right. The only excuse I can think of would be if he just got the Sencore sensor after previously owning a sensor that did not need dark readings (like the Spyder2 when used with Colorfacts).
Although I don't think this calibrator sounds like he deserves anyone to come to his aid, I will say that it can multiply the frustration to have the customer watching over your shoulder every minute of the calibration if you're having difficulty. Once you start having problems it can make you feel more self conscious, and then it becomes harder to think straight... But I can understand you wanting to be there, because if he's as incompetent as it sounds that he might be then I'd want to be there too to make sure he does his job.

weird things happen some times ?

So he calibrated with the AI off ? The boys are saying this is the correct way to do it.

I am not sure that your indecision about accuracy is a reason for the calibrator to return though.

FWIW,

Gregg

Gregg, can you elaborate on your comment a little more? To answer your question, yes, he calibrated it in the end with it off. But for a good 2 and half hours it was on in Auto Iris 1 mode while he was getting the wacky readings. I think he thought the auto iris was throwing the readings off. At least that is what he said under his breath. Then he turned it off while continuing to get varied readings..........then he realized the problem. The back and forth of the whole thing threw me..........do you see how I could have been confused and frustrated with the oscillation? Gregg, I appreciate your feedback. The bottom line is I want to know I got my $350.00 worth. I don't feel at this point the value in his services were rendered. When you throw in the PS3 being set to "Full" and "RGB" mode enabled for the display.......I hope you can understand where I am coming from.

Chad, he was definitely nervous. However, I asked him from the beginning if he felt more comfortable if I wasn't in the room. I think the complexity of my system and how it was setup was intimidating..........as was the remote control. I was with him from 1:00 when he arrived. If he was frustrated, I was way beyond it because I realized 2 hours in that maybe he wasn't all his credentials said. At one point I almost asked him to leave and come back when he was better prepared. I was operating the remote for the picture setting adjustments, and he was looking at his laptop with the Sencore program running telling me to move the values up/down. I should have known something was wrong when he started to yell at the laptop...... I was sitting in the second row and could see/hear the frustration as the readings would jump from positive to negative..........big differences here, not small ones mind you. He clearly was grappling with what was going on..........I think he believed his Sencore instrumentation was failing him.