Official JVC RS20/HD750 Owners Thread! - Page 110  

All the specs are for the projector only. The real spec that matters is the one in each real world setup. CR measured from the screen as well as ANSI. Problem is, there are very few who have the equipment, capable of measuring low light levels, from the screen. We're talking about reading down to four decimal places (i.e. .0003fL) for some. Those with high gain, smaller screens, possibly 3 decimal places. Now a black level of .001fL and a CR of 30,000:1 would require a white level of 30fL. I don't think we're there yet with the technology.

I believe what you're describing is measuring illuminance versus measuring luminance.

In other words, measuring the light coming directly out of the projector instead of measuring it off a screen.

There are pros and cons to each way, and I've always been a proponent of the latter, as removing the screen from the equation seems questionable as there will always be a screen.

Measuring illuminance is trickier to do correctly, unless you're careful.

What he said

We don't have Gregr's measurements yet but in the original "anticipation" thread, Cine4home said to their amazement they actually did get around
50,000:1 out of the JVC (around 49,000:1 if I remember). It was at lower lumens (between 200 to 300?...memory failing..) which made those numbers not available to probably the typical installation/screen gain, but nothing that wouldn't be viable with a high gain screen as I remember.

But with .0005 fL it's only 15fL
A small error in the low range affects the CR number significantly.

For example a 3 digit meter display's a value of .0005 as .001

We need to be very sure about the low level accurracy of the light meter used before drawing any conclusions about contrast ratio's

So true, another thing is many take the measurements out of context and apply different interpretations/meanings to the numbers.


The measurements from the projector are a way to evaluate/compare a projectors performance without the effects of the environment. One needs to be careful how they rely on the results, specifically when we don't know the testing process or the specifications of the test equipment being used.

As I have mentioned before, I have measured my RS2 and with a 2100 hour bulb, the black level is around .0006fL, with a room black level somewhere near .0003fL. Now at 30,000:1 that is 18fL and at 50,000:1 it would be 30fL. Since my RS2 is only near 4fL for white, it is quite a ways from 18fL. With a new bulb, light output was about double, still nowhere close to the required numbers for the "published" contrast ratios. There is no doubt that the high published numbers contribute to the actual performance we like from the JVC projectors.

A Top-Fuel dragster is reported to have 8000HP, however that is no guarantee it will run 330 MPH every time. By this, I mean the projector's performance in installation stands on it's own. Some will perform differently than others.

Well I have been having fun with JVC. My first HD750 had pretty bad convergence, and JVC agreed to replace it. The second HD750 had significantly improved convergence, but slightly brighter corners, so I returned it. JVC agreed to replace it again, despite saying there was nothing wrong with the second unit. My third HD750 had slighly better convergence than the first, was defintely sharper, and only ever so slightly brighter corners.

I will probably stick with the third, but am not sure if it is a refurbished returned unit or not, as it had 3 layers of tape on the box and one of the four feet was damaged.

I am dissapointed that a projector marketed as high end by JVC seems to have so much varienace in a key area such as pixel convergence and black field uniformity. I have been impressed however that JVC America does try to please.

I had some overlap with the first and third units, so was able to do A/B comparison, using the multi-zone output of my receiver. It was interesting to see how the OOTB performace varied so much. Also, because of the different convergence errors, when viewing pixel phase error test patterns, one had a very green tint, while the other a distinct pink tint. This translated to full white field test patterns as well.

I guess it is basically a good projector, but the buying experience has been very frustrating.

I finally pulled the trigger and now have the RS20 in da house. (Anyone familiar with my posts on AVS could be forgiven for not believing I actually did so...given I've talked about upgrading my display for something like 6 years now!).

Problem is I'm in the middle of my HT room reno, so no screen. (in fact...no wall). It's a bit of a bummer, being anti-climactic. I wanted to buy the projector last once the room was ready, fire it up and get the full "I did it" reward at the end. However I was told the price of the JVC was going up soon (due to the yen, I believe) so I grabbed one now.

I'm going to test my unit out at the ever accommodating Mrlittlejean's place this weekend.

Congratulations Rich Hope you'll enjoy it as much as I enjoy mine!

YES congratulations Rich! You finally did it. Hope your testing this weekend is a positive experience for you.

Congrats!
I've been following your search.
Now you can "focus" on tweaking.

Mike

Nice Rich. You won't be disappointed.

Now get the damn Stewart 1.3 and be done with it!!!

Hah, if only it were that simple! I'm doing 4 way automated masking. I still have buy the Stewart screen material, have a frame built for it, and order the automated masking stuff....which will hopefully work together.

Congrats Rich! Got mine yesterday as well.

Glad I had a chance to meet you. It's always nice to put a face to a member name.

Well, had a chance to play with it last nice. I think you'll be pleased.

The unit is definitely a jump up from my RS1.

Now I just need to get the grayscale tuned up.

Dennis

Rich !...(speaking as I pick myself up off the floor after reading this !)...well CONGRATULATIONS. I look forward to more of your thoughts...now go have fun !

Rich, It's good to know that there is some one more anal than oneself about doing thorough research before pulling the trigger. As others say, I think you'll be delighted.

It must have been two years ago that HoustonHoyaFan began noticing that you had been in the projector market for what seemed like a long time.

Congrats! I hope you enjoy it.

Shane Buettner has a nice article about the JVC HD-750 in this month's magazine. He certainly likes it to the point of purchasing the demo. As a JVC fan, it is interesting that he states on a couple of occasions that the HD-100 is a little bit sharper than the HD-750. He wrangled with the CMS, but at the "end of the day" sort of found satisfaction with the color. Good reading.

Having seen the RS2 and RS20 I can say one thing that didn't "wow" me with either model was the sharpness. I mean, a lot of material on the RS20 definitely "wowed" me for sure (which is why I bought one), but it wasn't the overall impression of sharpness that did it. Whereas some projectors like several DLPs I've viewed or the Mitsubishi LCD amazed me consistently with a sense of holy-cow sharpness.

Maybe a dumb question, but is that article accessible online? If so, can you provide a link? Thanks

Folks,

Since my HT room won't be complete for a month or two I'm hauling my new RS20 over to Mrlittlejean's place to check it out for any issues, before it goes back into it's box until my theater is finished.

I'd like to know what kind of issues I should check for? Some I'm aware of are: Excessive image noise (mrlittlejeans had to have his replaced for that issue), sticking automated lens cap.

Anything else? What are the important parameters to check to ensure I got a good unit?

Thanks,

Rich

For any owners of RS20/HD750 PJs, who might be thinking of an anamorphic lens for a CIH setup – do it!

I had my setup working prior to the arrival of the 750 and had some concerns about the recessed lens etc. and whether the beam would be too big by the time it reached the rear lens of my Prismasonic 1500FE.
No problems have arisen and the results are very good. I, however, have a throw ratio of 2.5, so for those with considerably lower ratios it might be advisable to go for the newer Prismasonic or other brands.
I have attached a few pics to show my simple setup. The PJ and lens sit on top of my equipment rack (no long cables, everything out of sight when viewing) and no need for complicated lens mounts etc.
Aspect ratio management and switching between sources is nicely handled by a DVDO Edge.

Once CIH is experienced there is no going back.

I would run the vertical lens shift several times to insure it will work properly since it will be boxed up for awhile.
I would also turn on and off several times to check and make sure you do not have the dreaded 3 flashing yellow lights.
Even Stevie Wonder can see the diff between my rs2 and the rs20.

^
Amen! After 2 straight defective units I would definitely check it out! Of course any lens shift issue like I had will be known quickly and even quicker you will know that you have the dreaded lamp failure issue. That happened to me on the 'replacement' HD750.

Good Luck Mr. Harkness.

OK
Follow the checks kutlow suggests, but plus... much important you must check:

1) Focusing ... Try a pattern 1 pixel thin, and check the ability to focus good and at best over the screen. Check too, uniformity of the focused pattern in every zone of the screen
2) Black pattern or use the "Hide" function on remote. Check on the screen the uniformity of the black. There Must be NO shading NO "lights angles" No zones with different tone of "lighted" Black
3) Use a squares grid or the internal green squares test Pattern.
Go near the screen and check:
Usually NO perfect alligment of the 3 matrix must be contained in 1/2 - 1/4 of pixed ( vertical or horizontal ) for 1 or at last 2 of the 3 primary colors.
If you find for ex. 1/4 pixel red shifted vert. this is in the tollerance
BUT .. the most important thing is that this 1/4 pixel shifted MUST BE contant in every zone of the screen !!
The bad news is if you find 1/4 pixel shifted up on the right and 1 pixel shifted down to the left ..
There's notthing you can do to adjust in this case ... better to return the machine for a replacement !

Sorry .. JVC are wonderful machines ! But the production is as is ...
I checked with my dealer the 1st group of RS20 arrived in Italy last 19 December. We checked them accurately to classify 1-10 range them.
Well among 20 pieces only 3 units gain up from 9 to 9,50 !!
We found 7 units from 7 to 8,50 BUT 5 units to return Immediately !!
As I'm done and I pretend and feeel... I should keeped only the first group of units gained from 9 to 9,50 !!
Obviously, mine unit is the one that earned the 9,50 vote !

^
Yup. It's a crap shoot. Same for RS1 and RS2.
First thing I checked was convergence - then uniformity/shading.

Yes - it would be nice to receive 20 units and be able to pick out the very best one! (lucky guy)

I would like to add to what has been said prior --the following:

1. Put up a 70 to 100 % white screen display pattern from HD DVE Basics, or other reliable source, and look for visible color non-uniformity that might bother you when watching real sources. Np one has reported a problem -but if your projector was a Sony SXRD front projector this would be an absolute requirement.

2. Listen to the fan to see if you here anything objectionable.

3.Bring up a black souce frpm HD VDE basics and look at the black image for light corners. The RS20 typically has no such issue which was prevelant on the original RS1..so black should be uniformly black.

4 Check both HDMI inputs function properly.

5. Check that your screen brightness with Normal power level is reasonable. and not dark.

6. Check that the lens aperature mechanism works well

The most critical items have been mentioned above--Convergence--lens Focus--Lens shift/focus and Zoom lens movements are working.

On focus I feel the best way to do this is to not try to focus on any image-including 1 pixel line images. Instead follow the wisdom of alll good color film printers (who focus on the film grain not on the image).. Focus your projector for the sharpest individual pixels in a large ares of pixels in a still framed image.-for example a white or light gray Bar or thick line stretching across the full screen. As you change focus a whole pattern of the individual pixels comes into focus -looking not unlike many small rectangles. Images are made of this smallest element in the image--focus on these pixel/elements -not on an image of unknown original camera focus/sharpness.

Good luck with your projector.

KT

Interesting. We were told that this round of JVC's were "different" in that QC was much more consistent (perhaps w/ regard to light path, wire grid ??? ) But there was certainly to be more uniformity unit-to-unit. This part of the thread would suggest otherwise.

The convergence "issue" is still there !
Finally solved the light corners from RS2 and forth ....
But added other production issues like dead lens shift action ... too much differences in focus unit by unit ... dead 1st startup units ( 3 leds blinking)
Strangely, in my experiece, we're returning more RS20 than RS10 ...
I don't know if it's a case or fatality .... but that all at now.
Plus, consider that due to the CMS issue, the RS20 requests are blocked here ...
There's almost low or no demand ... for this astonish projector .. It's a "crime" ...

Edit:
John Just to be clear .. I've not received 20 units to choose from ...
I went to my dealer/friend showroom and helped him into make the selection ( 1 work day for 20 units ... unpack, test, classify and repack ).
My dealer do this everytime for customers satisfaction.
He has an agreement with JVC PRO italian division to return the units that exceeded the 1/2 pixel tollerance in convergence and/or dis-uniformity.
This, IMHO, is the only way to sell these projectors and be confident they will be appreciate and preserve the JVC "Image"
Yes I'm a lucky guy to be a friend of him

The customers there are also very fortunate to do business with ya. There are a lot of wary potential customers out here.