Originally Posted by JonStatt
When you get a chance Kelvin, could you see what happens if you do the following?
1) Use low lamp for an hour to warm up and take a reading
2) Go to high bulb and leave it for 15 minutes
3) Go back to low lamp and take a reading
4) Wait 10 minutes and take a reading
I found after using high lamp and going back to low, that low lamp does not return to its previous output level. Over a period of 10 minutes or so it gradually returns although it often then seems to stay a tiny bit lower than prior.
Also, I found that if I play 3D material in high lamp for about 15-20 minutes and then go back to 2D and take a reading of max white (on the X75 this is colourspace off, high bulb, aperture 0) I can get the highest reading from the projector (just over 1200 lumens on my X75). I actually saw this with the X70 as well. I never understood why playing 3D seems to give you a high lumens output when you go back to 2D, but it shifts about 60-70 lumens doing this technique.
Thats quite bizarre bulb behaviour but funny thing is, I found this to be the same on my X90 - even though its the previous generation projector and bulb. No idea why this happens.
The other night I was experimenting with various screen sizes, apertures and lamp modes. I like to watch at 10fl or so but continually hear people on AVS preferring much higher. I found I could get as high as 40fl but too small a screen so I decided to settle on 26fl, 117" screen size and watched a couple of movies just to see what the talk was with this high brightness preference.
But while I was taking all my recordings, which I done 1st in low lamp and then all over again in high lamp - when I switched back to low lamp I was a little bit freaked out when I checked the readings in low lamp again. I sort of thought that it might be a little bit higher coming from high lamp but it was over 10% lower. I thought that my frequent use of high lamp was beginning to take its toll on the bulb but after about 15 mins, it got close to the original readings - but not quite. I was a little bit thankful it sort of came back but at the same time, I'm a little bit worried at why this happens.
I will often use low lamp for some things and high lamp for others so its disturbing me that this will in fact damage the lamp. I don't know what lamp I'm using - I would like it to be the 3 but in reality, its probably version 2. I lost my zero bulb notes but from 70 hrs to my now 170hrs its dropped 8%.
As a side note, I've been trying to create some formulas which show that when you zoom back, lux increase, fl increases and lumens decrease. Same for aperture, what effect each setting has on output and also variance between high and low lamp.
I haven't enough measurements taken to be sure yet so I'll need to do more but one thing I'm pretty confident is that on my PJ, moving from low lamp to high lamp increases light by 54.2%. This was taken from 16 measurements at various apertures and 2 screen sizes and all readings where between 53% and 55% if I exclude ony 2 extremes - one measurement of 51% and one of 56% which aren't too far off the mean average anyway.
I think I can hang my hat on that number. Just need to create something for aperture and zoom now....that'll be a little more difficult....its certainly not linear and early numbers are showing that there is about 1/4 of the zoom range where lumens hardly drop at all - thats how I found my 117" 26fl sweetspot. At 109" there was only a marginal change.