One last point, taking a bit due to all of your hidden attacks
QUOTE:The ohmic approximation is just plain way off.
Before a certain CPFer attacked me for using the re-rating formulas, I would have thought that they were so well established as to be common
ground here on CPF. But I learned that that was not the case. So I have inserted this post to the thread to support the use of the re-rating
Ohmic approx was used because you never provided *us* with the current at the baseline until after the fact. You told us the rerated
parameters and that the filament was near mealting as per Willie.
The ohmic approx is sufficient in this case but the both current and voltage measurements would have been better. You finally provided it and
guess what, it was appreciated. It just so happened that my measurements (and approx) yielded a measurement closer to brocks, not your guess.
I even gave the formula for determining the tungsten filament resistance.
T = -1.86(R/R0)^2 + 206.6(R/R0) +118
R= resistance of filament at temp
R0=roomtemp(0 really but no need to freeze it)
When the filament temperature is already in the 2800K+ range and the Tdelta is very low it approachs ohmic behavior . When the gradient is
large, it is classical nonohmic. If you can derive the resitivity at a particular temp, the change in R can be derived via the diffeq at the
new temperature. You provided the temperatures/color temp.
QUOTE: People like PaulW and Ginseng are ingenious and inventive enough to come up with a method for approximating the real output of our
incan mods and all you can do is to try to tear it down. Talking about all the many reasons why it isn't valid, or is only valid in this one
particular case and on and on.
I take it you missed my post last year outlining use of a digital camera,photoshop, ceiling bounce and a light of known output to derive
light box type of lumen estimates. I try to contribute to yah know...
march 9 2005
...I did one step more. I did a ceiling bounce with a white door being photographed in manual mode. I used a p60 with new batteries for
reference, the l2, u2 and u2 + l2.
I did a 25x25 point sample at a point in each picture to derive the rgb. I summed the components and applied a ratio to the known approximate
P60=1*65lumens=65 lumens (hard math) (22 was the r+g+b score)
L2 rgb score =33 33/22 * 65 = 97.5 lumens
U2 rgb score =41 41/22 * 65 = 121 lumens
u2+l2 rgb score =78 78/22 * 65 = 230 lumens
Of course there is error in the ccd due to the bayer filter and other issues. The system isn't technically sound but is isn't a bad estimation
assuming the p60=65lumens was a good calibration. So the simple test does help to back my claim of the difference between the two.
I'd imagine I can make it work better, including giving spectral results but it was more of a verification. I need to do the same without he
B65 battery and also the 3x123 u2 which seems to give about a 20lumen increase (just a test not a long term burn because I like the u2 and I
only have 3 levels vs 6 when doing this)