I have a Benq W5000 front DLP projector. I have calibrated it to roughly D65 and the light output is only 253 lumens. The lamp is on low so I am losing maybe 20% there, but still thought it would be higher. The iris is fully open.

Here is the method I used to achieve maximum brightness. Using GetGray I projected and adjusted each primary ramp for the maximum range. I then used my Spyder2 and Calman to bring down the green and blue to match the red output. The result was pretty close to 6500 from 10 IRE to 100 IRE and spot on D65 at 100 IRE. The light output is very low though. Is my procedure a reasonable one to obtain max light output at D65? Next question is if I have to go cooler to increase the light output, do I just increase blue? How do I calibrate properly for a higher color temperature?

What happens when you start to push the contrast up. You could give up a bit on D65 at 100% for more light output as long as it does not blow out at 90%.

Greetings

You don't mention how large your screen size is. 100" ... 150" ... light output is relative ...

regards

Derek,
I have the contrast up to the max just before saturation, any higher and I'll clip the whites.

Michael,
My screen is a generic gray, 120" diagonal, so 253 lumens is relatively low. My previous pj (Mits WD2000) put out about 800 lumens. Surprising thing is the image is not that bad, I suppose my eye's iris must be compensating. The most noticeable difference is the brightness of stars or text on a black background. With only 5 fl at the screen, assuming a gain of 0.8, I'm way below the recommended.

Greetings

Then that is it. If you clip it ... then you don't want the contrast any higher. If you are just short of clipping, you might be in the discoloration range where contrast is still too high so keep an eye out for that.

Beyond this ... you got the wrong projector then. :(

If you had a white screen, you'd get more light output out of it too.

Regards

Just for experimentation, I would like to try calibrating to 7500K (D75?). Derek, can you tell me how to do that with Calman?

Just for experimentation, I would like to try calibrating to 7500K (D75?). Derek, can you tell me how to do that with Calman?

When you open an input for calibration under Options->Grayscale->White Point Target you can select from one of the many targets we provide, "D75 SMPTE-C" is one of them.

Let us know how you get on. The W5000 was one of the projectors I was going to look at to replace my aging H79.

Thanks Derek, I'll give that a try when I get back home in 2 weeks. For D65 I adjusted the 3 primaries to be equal. Will that be different if I set up for D75?

Thanks Derek, I'll give that a try when I get back home in 2 weeks. For D65 I adjusted the 3 primaries to be equal. Will that be different if I set up for D75?


The D75 RGB mix internal to us will be different with more blue and less red but you still adjust for the primaries to be equal. It's easy to see the effect of choosing a different white point. With the way you projector is now calibrated by changing the white point from D65 to D75 you will see the RGB's will no longer balance until you move them again.

Why do you want to further compromise imaging performance in an effort to compensate for poor design decisions? A screen must be matched to the capabilities of the projector. You picked the wrong projector, the wrong screen, or a combination of both. Why not replace your screen fabric with a 1.3 gain white screen, rather than using the wrong white point in the image? Was this system designed by a professional or did you do it on your own?

If you are tempted to sacrifice image fidelity for a larger picture, why not just get a smaller screen and sit closer? I find it puzzling that you inhabit the realm of display calibration, yet are so willing to alter color accuracy for the sake of size. Just about every consumer display on the market sacrifices image accuracy for brightness out of the box.

The calibration industry has been promoting image fidelity over light output since day one. Intelligent system design can compensate for lower output displays, as long as the user is willing to control ambient light. An accurate gray scale is foundational to a correct image. Surely there is a better way to improve your system's performance than by moving even farther away from standards. It sounds to me like you need to re-think your approach and re-evaluate your entire imaging system. What is your goal? If it's not image fidelity, why are you in the calibration section of the forum?

Best regards and beautiful pictures,
G. Alan Brown, President
CinemaQuest, Inc.

"Advancing the art and science of electronic imaging"

Welcome to the reality of calibration - manufacturers market based on blownout specs and do not care what calibrated performance ends up being.

Get a gain screen - something like DaLite High Power. You will be much happier. If you have a framed screen just buy the material and roll up the gray for the next upgrade if a brighter PJ.

Thanks Kras for useful feedback. Not sure I want to go high power though, what do you recommend in the 1.5 to 2.0 range?

If you use ceiling mounts - that is the range HighPower will be.

Caution should be exercised when considering higher gain screens. The consequences of hot spotting and color shift will need to be weighed against the desire to compensate for too dim of a projector. If image fidelity is paramount in a display system, the right balance of all component performance characteristics requires careful thought and planning.

One of the best discussions of screen gain in recent memory was an article by Joe Kane in issue #119 of Widescreen Review. If you are a subscriber to the magazine, the article can be downloaded from their site. Non subscribers can order the back issue (April '07). I strongly recommend it.

DaLites HighPower does not hot spot when used with ceiling mounts - because you are already at the half gain angle (1.4x).

It indeed does hot spot if you put your head by the PJ lens and look at the screen.

It is a great solution for those who did not realize a calibrated PJ would be dim.