How do you know when your meter needs calibration???

The only way is to check it on a reference system.

That can be true. You can also use a stable light source and track the readings over time to make sure it has not drifted.

What is a good stable light source?

How about the sun?? I don't mean pointing the sensor directly at it, but what about measuring the reflection off some white paper or maybe some shade of grey kodak paper to tame the brightness slightly?

I'm in the UK, so it's not often I'd get chance to try this method!

But thats only going to be stable for another 1 billion years or so... how can I honestly live with myself if I used this methoid...

j/k

Now the question is what is a good cheap large "pure" white piece of paper.

Or does any White matte finish photo paper work?

I don't know what 'does' work as it was only a suggestion. It might be worth looking on photo paper websites to see if they quote any standards, though they might not be to D65. I only got my I1-LT for Christmas ans the there hasn't been much (if any) sunshine since, so I haven't been able to try it. The other thing is that it is cold outside so that would effect the sensor and might make the readings meaningless....so I'll have to wait for the summer to try it out unless there is a method I could do now that would allow me to check the sensor again in future to see if it has drifted?

Perhaps using a 'daylight' bulb and a piece of white paper in an otherwise darkened room. If I keep the bulb and paper and check again in the future the reading should be consistant (if the room temp is the same)? This would at least show if there is a drift in the sensor even if the exact reading isn't at D65.

Just a thought anyway.

I'm making an assumption that my new meter is reasonably accurate having managed to perform a good greyscale adjustment starting from the 'warm 2' colour setting on my Sony LCD TV. However, my projector is completely off in every mode I've checked, even the ones generally regarded as close to D65 out of the box, like 'Colour 1' (it's an AE3000). I'm getting a low blue reading across the whole 0 to 100 IRE range and I'd understood that if anything I'd be short of red?

I managed to adjust 'Cinema 1' mode to a delta E of <5 between 30 and 90 IRE, but looking at Cine4home's review, their out of the box result was closer than that. I had to max out the blue contrast to achieve my result, so I'm wondering what is wrong: My sensor must be resonably accurate given my TV results ('warm 2' is generally reported as being close to D65 and my small adjustments to the RGB settings seem to support this). I have gone over the Curt Palm calibration thread and set HFCR according to the suggested preferances (in fact the same as for the LCD TV).

I realise that this sensor is not going to be as good as a $$$ one, especially at low IRE, but although I'm pleased with my TV picture, I really got the I1-LT to set up my PJ.

EDIT: I've had a suggestion on a UK forum that it might be my initial sensor calibration. Thinking about it I only did it once at the start of a 4 hour session and there may have been light from the PJ shinning at it (though I did place it onto a DVD case as recommended). I'm going to try a quick run though tonight and pay more attention to the initial sensor cal with all lights off and the PJ lens covered during the cal. When I did my TV calibration I had all the room lights off and the TV backlight off during the initial sensor cal...so maybe that is why the results were better?