Hello,

I did my best to calibrate my front projector using an eyeone LT and the ColorHCFR software. I'm very happy with the result.

Is it possible now to calculate the lumen output of it?

Thank you.

Pitou!

Try this:

Lumens = (fL x screen size in SqFt) / screen gain

You should be able to get the fL from your ColorHCFR session.

It gives me around 2000 lumens, which is probably wrong. What unit is the lumens using this formula?

I have a Sanyo Z2000. Here are the values:

fL = 7.583 (this is for the 100 IRE pattern)
screen size is 102" diagonal, so giving 370.83 SqFt
screen gain is 1.4 according the the website. I'm using digital grey lite goo paint.

So 7.583 x 370.83 / 1.4 = 2008.57

What did I do wrong?

Thanks.

Pitou!

370.83 SqFt?

It's 30.9414 SqFt..


btw, 7.583 fL is low for FP

You used the wrong surface area.

The lumens calculate to 160 based on your assumptions and reducing the significant figures to 2. I suspect the 1.4 gain is higher than it is in reality. Your light meter will also be way off since it is not really a luminance instrument and will not see screen gain. Using a screen gain of 1.0 for that instrument gives 230 which is more likely what your tools are indicating than the assumptions you made.

370.83 SqFt?

It's 30.9414 SqFt..


btw, 7.583 fL is low for FP

The actual luminance will be 11 fL if the screen gain really is 1.4 because his tool will not see screen gain. .

oh, right, I miscalculated the SqFt. :)

As for the gain, you are probably right as this is a theoretical value.

I know 7.583 is low but I can get any better once it is calibrated. I heard people getting around 8 when this Z2000 is calibrated. I may be wrong though.

Any tricks to improve it?

Thanks

Pitou!

true, he's using ColorHCFR, I do the screen offset but I use CalMAN Pro..

I assumed he already took that into account but now realize I should have questioned everything with that original SqFt calc.. :)

Any tricks to improve it?

Thanks

Pitou!


Move it closer to the screen :P

I assumed he already took that into account but now realize I should have questioned everything with that original SqFt calc..

You should have! I'm not sure what I was thinking about! I really forgot to divide by 12 the l/w :) :)

Just one of those days, you know :)

oh, right, I miscalculated the SqFt. :)

As for the gain, you are probably right as this is a theoretical value.

I know 7.583 is low but I can get any better once it is calibrated. I heard people getting around 8 when this Z2000 is calibrated. I may be wrong though.

Any tricks to improve it?

Thanks

Pitou!

If you really want to know what is going on you need better tools. A real luminance meter would be the first place to start. Published gain values for screens with gain are frequently wrong.

I understand, what would be a good and not too expensive luminance meter and where to buy it?

I understand, what would be a good and not too expensive luminance meter and where to buy it?

The cheapest I know if is the Sekonic L-758Cine. Once you have gone that far you might want to get an i1 Pro. Hiring someone who has great tools may be a better option.

I'm thinking of buying an i1 pro since I bought the i1 LT. Does the i1 pro give an accurate fL value?

I'm thinking of buying an i1 pro since I bought the i1 LT. Does the i1 pro give an accurate fL value?

Much better than the LT, but not as precise as something with a lens targeting system. The Sekonic is a better luminance meter for front projection because of the lens, but it will not measure color. The i1 Pro is a much better color tool than the LT. I am not sure it is of much value to know your fL exactly unless you are willing to change something or believe your projector is defective.

I suspect the i1 Pro will be about within about 20% of the real fL value. The Sekonic will probably be within about 10% a PR-670 within about 1%. This is based on personal experience with all of these instruments.

umr,

Understand, since I'm still a newbie in this world, I guess I should ignore that lumen value for now.

And anyway I'm much more happy with the image I'm getting now. In fact, I think it's the best I've seen with my setup at the moment.

But, hey thanks very much for the explanations.

Pitou!

I'm thinking of buying an i1 pro since I bought the i1 LT. Does the i1 pro give an accurate fL value?Not very. Although it returns more accurate results with color, it is less accurate than even inexpensive colorimeters for luminance readings. The industry standard for luminance readings is the Minolta LS-100.