>…wandering through the film spec sections of the cinematography.net
>site and I'm stumped with the Fuji exposure curve graphs.
If I can successfully dust off my self-taught math, on the base line 0.0
equals 1 lux second of illumination on the surface of the film.
Since this scale is in log values, each log .3 is equal to one stop.
So on the Fuji curve, to the right of 0.0 is .50, which will equal 1-2/3
stops more exposure, 2.66 lux seconds (each .1 advance on the log scale
is equal to 1/3 stop.) The last step to the right is 1.0, which would
be 3-1/3 stops, 10 lux seconds. To the left of 0.0 the first value given
is 1.5 with a minus sign over the 1. This means a value less than 1, i.e.,
a fraction. In terms of stops, this is 2-2/3 stops less than 1 lux second
or .166 lux second. The next value given is minus 1.0, which is 3-1/3
stops less, .0833 lux second.
Okay, I'm already in over my head! Some math expert (or just anyone who
had more than basic high school algebra!) can chime in here and clear
up my errors.
Wade K. Ramsey, DP
Dept. of Cinema & Video Production
Bob Jones University
Greenville, SC 29614
>Okay, I'm already in over my head!
Not quite as deeply as you think, Wade. The Fuji files are presented in
a particularly unfriendly way - exactly correct for mathematicians, needlessly
obscure for others. But your gist is correct.
1) Every change of 0.3 (log lux seconds) is one stop
change in exposure. That's the key to it all.
(0.5) step on the graph is therefore 1 2/3 stops (not really a useful
division for us)
The negative notation (1.5 with a minus over the 1) or "bar one point
five" is actually (-1 +.5) or -0.5. Useful in some mathematical notation,
not so wonderful here.
1 lux second (the zero point on the graph) is equivalent to 48 lux at
Lux is a measure of intensity of light falling on the film. 10.76 lux
are 1 foot-candle, but there are other factors between your exposure meter
and this graph. Don't go there.
6) It's really all about relative exposures.
is what lesser souls call "E" for exposure. D log E curves compare
Exposure against density.
Group Technology Manager
>Okay, I'm already in over my head!
Dominic (with an i) wrote:
>...** The negative notation (1.5 with a minus over the 1) or "bar
one point >five" is actually (-1 +.5) or -0.5.
Thanks for the rescue! That minus 1.5 kind of baffled me, I'd never seen
it noted that way before, and miscalculated.
Wade K. Ramsey, DP
>Thanks for the rescue! That minus 1.5 kind of baffled me,
Uh oh. I'm in trouble again. I'm still safe assuming that .3 on this scale
is equivalent to one stop, correct?
I so liked your original answer, Wade! Don't tell me it was all an illusion!
I'd love to try Fuji stocks again after what Geoff showed us at the workshop,
but I don't know lux seconds from seconds at the Luxor.
Art Adams, DP
>...Uh oh. I'm in trouble again. I'm still safe assuming that .3
on this scale >is equivalent to one stop, correct?....
Yes, that's the essential thing. I got into trouble trying to translate
those minus intervals. But as Dominic pointed out, don't try to translate
those numbers into camera exposure. These list the illumination on the
film surface that were the result of exposures given the film by a sensitometer,
not a conventional camera with lens.
But you can see the effect of relative exposures in stops over the range
of the curves.
Wade K. Ramsey, DP
>I'm still safe assuming that .3 on this scale is equivalent to
one stop, >correct?
0.3 log E, or log H or anything like that, is one stop.
0.3 log lux seconds is one stop.
0.3 Density is one stop.
the more convinced I am that you should only use these
curves as an indication of the contrast characteristic, exposure range
etc of the stocks in question.
The lux-second (metre-candle-second) scales don't seem to agree with each
other, nor with the exposure that one would expect. Moreover, the Kodak
curve uses the "bar one point five" notation differently from
the way Fuji does.
Does anyone on this list understand photometrics? Who
can tell an apostilb from a foot lambert from a nit?
Dominic Case wrote:
> Does anyone on this list understand photometrics?
I couldn't explain it, but I could tell you which was which if I was looking
Anders "nit picker" Uhl
>But as Dominic pointed out, don't try to translate those numbers
into >camera exposure.
For some reason I didn't get Dominic's post. So what I think you're telling
me is that those curves will give me a vague general idea of how the film
responds, but really aren't practically useful other than to give me a
vague idea of how contrasty they are?
Should I be discounting Kodak's graphs as well?
>But you can see the effect of relative exposures in stops over
the range >of the curves.
True, but how useful is that? Given that I rarely get to test stocks before
using them, if I wanted to take of one those bad boys out for a spin on
the telecine it'd be nice to have enough over and underexposure info to
keep me out of trouble. I feel like the Kodak graphs give me that.
Are the Fuji graphs different?
Marketing or science, marketing or science. One never knows...
Art Adams, DP
Dominic wrote: >...Does anyone on this list understand photometrics?
Telling them apart is one thing, understanding photometrics
An apostilb can be considered a reflected lux, that is,
surface luminance (brightness) equal in unit size to lux, which is a measure
of illumination. One apostilb is luminance equal to one lumen per square
1 Lux is the amount of illumination received by a surface that is at all
points 1 meter from a standard candle. 1 lux equals .093 footcandle.
A footlambert can be considered a reflected footcandle,
surface luminance (brightness) equal in unit size to a footcandle, which
is a measure illumination. One footlambert is luminance equal to one lumen
per square foot.
(One footcandle is the amount of illumination received by a surface that
is at all points 1 foot from a standard candle. 1 footcandle equals 10.76
A nit is a unit of measure of luminance (brightness)
equal to 1 candle per square meter, also called a meter-lambert. (A lambert
is luminance equal to 1 candle per square centimetre.)
So who cares? Our incident meters measure illumination in footcandles,
but our spot meters (except for one made by Spectra) aren't calibrated
in footlamberts. Wish they were, it would make sense in set lighting.
So we translate the two by switching to exposure and going with f/stops.
It would be great if Sekonic, for example, would make a version of their
608 with a spot meter that read in fL. That way, you could, for example,
check a location wall surface ahead of time by simply reading the ambient
fc at the surface, then the fL reflected from it and instantly know the
amount of absorption it has; 10 fc- 5 fL equals 1 stop absorption.
Maybe others don't think this way, but I like to light in footcandles.
That's a nice unit that we are all familiar with (or should be) that is
independent of exposure. You can tell your gaffer you want 100 fc, without
explaining it as f/2.8 at 1/50 with EI 100 film.
So being able to relate relative surface luminance’s in the set
in terms of footlamberts would be a convenient system. And no, I can't
say I understand photometry, only bits and pieces of it!
Wade K. Ramsey, DP
>Maybe others don't think this way, but I like to light in footcandles.
I've worked with DP's who work in footcandles, and I've done it a few
times, but I think I'm leaning towards the "light it by eye and pull
out your meter at the last second" school. I like the idea of lighting
a set so it looks nice and then figuring out how to expose for it later.
For me it's often just a matter of boosting the fill level a little bit...or
taking a deep breath and not touching the fill at all.
My personality is totally geared towards lighting in footcandles, being
the control freak that I am, but I find that when I loosen up a bit I
take more chances and get better results.
I'm trying to work more intuitively, and I'm planning accordingly.
Art Adams, DP
>The more I look at the Fuji curve……and compare it
with a similar >Eastman curve……the more convinced I am
that you should only use >these curves as an indication
of the contrast characteristic
Those two sets of curves seem really at odds with each other.
First, I checked with my local math guru, former head of our math dept.,
and he had never seen negative log notations done the way Fuji shows it.
We decided that the chart must have been done by the same guy who writes
the English translations of some
Japanese camera instruction books!
Anyway, the Kodak notations are normal :
Halfway between log 0.0 and bar (minus) 1.0 is bar 0.50. But as Dominic
said, these two particular charts don't jibe. Since the Kodak chart gives
both log E in lux and plus and minus stops from normal, it is very helpful,
and I think Art Adams will find this useful. But if the normal exposure
(18% grey) for Kodak 200T is bar 1.6, as Kodak says, yielding a blue density
of about 1.5, a green density of 1.3, and a red density of .7 (these are
approximations), and you look at the Fuji chart for those same densities,
they are achieved at a log E of about bar 0.86.
Kodak states that for 200T middle grey is at bar 1.6 and white is about
bar 0.9! That puts 18% for Fuji 250 at practically the same exposure as
white for Kodak 200T, and Fuji's white at about bar 0.16. Wouldn't that
indicate that the Fuji 250 is actually about 2-1/3 stops slower than Kodak
Apparently, it isn't, but the charts would seem to me to indicate it.
The curves on Fuji are shifted to the right compared to Kodak, indicating
more exposure is needed to achieve the same densities.
Dominic, your lab processes both these stocks. Is my math about right?
Do both these stocks read about the same densities for 18% grey exposure?
What do you make of this? Do you think they might have printed the wrong
chart? Will our hero find true love at last...?
Wade K. Ramsey, DP
>An apostilb can be considered a reflected lux,
. . .
For all those who have already deleted Wade’s post, be warned :
the short exam will appear tomorrow.
Those who fail will be forced to say in cml-basics for another year.
>I feel like the Kodak graphs give me that. Are the Fuji graphs
No - they give exactly the same level of information. Simply rule up a
grid of 0.30 intervals on the Fuji graphs and that will give you the one-stop
scale that is more clearly shown on the Kodak graphs.
The information you get is more than a "vague idea of how contrasty
they are". It's a very precise idea of how contrasty they are, what
the exposure latitude is and so on. The only thing you can't read directly
is what exposure - in camera terms - will give you a specific density
on the film.
As Wade says, the lux-second values relate to a direct exposure from a
sensitometer, not to an exposure meter reading. So, ignore the absolute
values of log E or log H or lux seconds, and simply use the scale that
a change of 0.30 in that value is equivalent to one stop.
As a reference point, if you draw a vertical line through RGB densities
of .80, 1.20, 1.60, you will have normal exposure of a 16% or 18% grey
card. Kodak show that as "N" or 0 stops. You'll need to do it
for yourself on the Fuji graph, going for an "average" value,
as the layers are balanced a little differently.
For some reason I'm not getting Dominic's posts. Very strange.
>The lux-second (metre-candle-second) scales don't seem to agree
with >each other, nor with the exposure that one would expect.
Does this seem to imply that Fuji needs more light to get the "equivalent"
exposure density from an equivalent Kodak stock? I've always heard that
Fuji films aren't really as fast as Fuji says they are. Maybe this bears
On the other hand they could just be saying that you get better results
from less density on their stock. It bugs me that Kodak tells you exactly
where black, white and grey should fall, and Fuji says no such thing.
Also it concerns me that Fuji says this test was shot under 3200 Kelvin
with a Fuji SC-41 ultra violet filter in order to emulate natural conditions.
Maybe I'm missing something but I don't shoot under 3200 Kelvin light
with a UV filter.
>Moreover, the Kodak curve uses the "bar one point five" notation >differently from the way Fuji does.
It simply appears to be a mistake. Someone got confused. Instead of -3
-2.5 -2 -1.5 -1 -.5 0 they decided to do -3 -3.5 -2 -2.5 -1 -1.5 0. Seems
like a really sloppy mistake to make on a major marketing document.
>The curves on Fuji are shifted to the right compared to Kodak,
indicating >more exposure is needed to achieve the same densities.
That's what it looks like to me. The optimum "lux second" exposure
looks to be around 0.5 on the graph (or -1.5 in their notation).It makes
me wonder if two people made bone-headed mistakes on the Fuji chart. I
wonder if one person put -.5 where -1.5 should be, and someone believed
the first guy and drew the curves that way. That might explain why the
optimum "grey" exposure falls around the line marked -1.5 but
is really .5 when you correct the notation.
Tell me I'm wrong, but I think mistakes were made. Serious mistakes.
Dominic, do all stocks print "normally" at the same densities?
I've got your book sitting here but I haven't gotten around to reading
It's also interesting that, according to Kodak, 74 gives you about 6 stops
over and 3.5 stops under (sounds right on the under, I have no experience
with that far over on 74). To get the same values out of Fuji you have
to assume their grey falls at -1.0.
If, instead, we assumed that their grey fell at -0.5 (or their -1.5) then
the F250 would have a little over 4 stops underexposure and 4 stops overexposure,
which makes a lot more sense to me.
Art Adams, DP
Hurrah! Now I'm seeing Dominic's posts again.
>But the overall offset between the two stocks seems wrong, as
Wade >says. One of them is out by about 2 1/2 stops relative to the
I'm totally convinced that someone put the "-1.5" in the wrong
spot, and someone else drew the curve to centre on that mark. The only
problem is that the "-1.5" was put where "-0.5" should
have been. The centre of the curve, if we go by Kodak's -1.6 reference
grey, should centre where -2.5
occurs on the Fuji graph.
"Who's on first?" "I don't know!" "Third base!"
My dad the engineer would be proud.
So, that little error in notation only throws the graph off by about 1.1
(-1.6 to -0.5). That's what, three stops and then some?
No big deal.
I looked up the graph for Fuji's 500D stock. Grey looks like it falls
If someone wants to they can try to explain to me how exposure can be
described in negative numbers. I would love to hear from someone from
Fuji on this issue.
PLEASE! I want to try your stocks for the first time in years. And, to
Wade and Dominic, thank you very much. I'm getting tons out of this conversation.
Art Adams, DP
Ooops. My mistake.
The 500D has the same numerical error in the characteristic curve graph.
Fuji has me totally baffled now. I'll have to go through their other stocks
tomorrow and see if the same errors are there too. From Fuji I'd like
to know: what are "normal" 18% grey RGB densities for their
stocks? Kodak's .8/1.2/1.6 don't carry over at all to the Fuji graph.
Art Adams, DP
Wade (and others who are still with us on this)
Thanks for laying this out. I tried to express my same concerns (about
the mismatch between the Kodak and Fuji results) and then deleted it.
However, you've expressed the problem quite clearly.
The two stocks are only 1/3 stop different in speed, and when exposed
"by the book" come up with comparable results. The Fuji tends
to grade at a different RGB balance, (higher on the red, lower on the
blue) which you can see in the slightly different relativity between R,
G & B curves on the two stocks. But the overall offset between the
two stocks seems wrong, as Wade says.
One of them is out by about 2&1/2 stops relative to the other. My
only conclusion is that one company or the other is using a different
idea of what exposure really means. Perhaps John Pytlak and Andy Coradeschi
could summon up the might of their respective research labs to account
On the "bar" notation, I'm only relying on my distant memory,
but it's usually reliable on useless things like this. I am sure I was
taught the "bar" notation as a way of plotting negative numbers
on a graph. The idea is that major increments of 1 go _3 _2 _1 0 1 2 3
etc, while the minor increments always go .0 .2 .4 .6 .8 etc whether the
scale is to the left or the right of the zero or origin.
This a sequence of numbers would go :
_1.0, _1.2, _1.4, _1.6, _1.8, 0, 0.2, 0.4, 0.6, 0.8 1.0, 1.2 etc (using
“_” to indicate bar, not minus)
It does have its good points, though they may be hard to see. Enough nerdiness
for one posting.
>If someone wants to they can try to explain to me how exposure
can be >described in negative numbers.
Easy - if you've stayed with us this far.
We are describing exposure in LOGARITHMIC terms. Calm down and breathe
quietly everyone. As you know, every time you open up one stop, you are
doubling the amount of light that reaches the film.
Two stops, 4x the light; 3 stops, 8 times, and so on. So the log E scale
is really more to do with stops than actual exposure (those darn lux second
For arcane reasons, we use a log scale that increases by 1, not for every
doubling of the exposure, but for every 10x the exposure. Drawing the
line between the dots, it turns out that the log scale increases by 0.30
for a doubling of the exposure (1 stop).
It follows that it decreases by 0.30 for every halving of the light, or
reduction of one stop.
Nearly there. For more arcane reasons, it turns out that the logarithm
of 1is 0. (You can think of whole-number logs as the number of zeros after
1: so the log of 1,000 is 3 etc).
So, on the scale on the graphs that started this whole thing, an exposure
of 1 lux second appears as 0 on the log scale. An exposure of 10 lux seconds
would appear as 1. Going down towards underexposure, an exposure of 1/10
lux second must be minus one. 1/100 lux seconds is -2 on the lof scale.
And so on.
The significance of the log scale is that it matches the response of film,
giving the straight line in the middle of the graphs you are looking at,
allowing an easy measurement of gamma or contrast from those lines, and
it also mathces (quite closely) the response of the eye.
And yes, Art, if you have my book, you WILL find it in there.
>It's also interesting that, according to Kodak, 74 gives you about
6 stops >over and 3.5 stops under
Really, I think is probably correct on over. I wouldn't go around putting
all the bright things in a scene 6 stops over, but I've found you can
sometimes recover as much as that in telecine; and you can see that latitude
in specular highlights.
This is one of the high bars "digital" needs to reach. IMO.
>A nit is a unit of measure of luminance (brightness) equal to
1 candle >per sq. meter, also called a meter-lambert.
My Sekonic 778 measures in candelas per square meter although not directly
I had no idea until now I was actually measuring nits, no wonder I get
those funny looks from people when I'm using the meter....
Do I need to clean the filter & get those old nits out of there ?
>I had no idea until now I was actually measuring nits, no wonder I get >those funny looks from people when I'm using the meter....
>Do I need to clean the filter & get those old nits out of there ?
Only if you're a nit-picker.
Wade K. Ramsey, DP
Art Adams wrote:
>...I've worked with DP's who work in footcandles, and I've done
it a few >times, but I think I'm leaning towards the "light it
by eye and pull out >your meter at the last second" school.
That's fine, a lot of folks work this way, Roy Wagner being one. But,
I like to work to a certain stop and to do that you need a specific light
level. With my lenses I know what stops work well and what don't in a
situation, so I'm working to that. Those who light to a certain stop because
of that lens's inherent contrast characteristics will also have to specify
the light level up front. So if I'm doing that, I like to do it in terms
of footcandles as a reference.
I know the stop…anyone else only needs to know the light level.
Wade K. Ramsey, DP
>It's a great buzz watching people look at the video assist and
shake >their heads and then to see them watching the rushes!
Yeah, well... it'll be interesting to watch me too! I can only imagine
what was happening on the set of your Liza Minelli promo...the background
was so deep and rich and only just barely there. It was wonderful.
I think Roy Wagner said in an article a while back that he lights a scene
and then measures the darkest area, lightest area and a middle grey, figures
a stop and shoots. I like the idea of setting parameters and then not
worrying about knowing in advance where everything will fall, just knowing
that it will be visible in the end and that the balance will be there.
I hear stories about cinematographers who take a very systematic approach
to things, and others who are very intuitive. The results from both sides
are excellent, so I'd like to try to be one of the intuitive group for
Art Adams, DP
>...all the "constructive criticism" will, I'm sure,
result in positive >improvements here at Fuji. In fact, it already
has, as I'll explain later...
And it is constructive. I actually want to try your product. I just had
a few questions first.
>First of all, Fuji's method of expressing negative
log numbers is, as >Dominic Case points out, absolutely correct.
It's back to high school for me. Math never was my strong point. I'm going
to have to go over this part of your post most carefully to understand
>Secondly, the Fuji MoPic engineers use the UV
filter to try to simulate >actual photographic conditions, i.e.,
on most sets there is some glass >between the light source and the
Interesting. Makes sense, I suppose. It would be good to explain that
in the literature. It would give the impression of careful and exacting
testing, instead of making uneducated louts like myself wonder…"Why
a UV filter under tungsten light?"
>Thirdly, you all did help us to discover a misprint
in our characteristic >curves, and the changes are already in the works.
Excellent. I'd love to see the new ones when they come out.
>Lastly, I'll describe how to apply stops to the
log exposure curves. It's >part science and part voodoo, which is why
Fuji's engineers are reluctant >to present this type of information
Nevertheless, it is helpful. Kodak's spec sheets are very user friendly
because they give both lux seconds and camera stops, and camera stops
are what most DP's think in. Kodak also points out where grey is, and
where over and underexposure latitude starts. I feel like Kodak charts
are written for someone like me. Fuji's charts seem to be written for
engineers, which is not the target market. I'd love for Fuji charts to
be more "DP friendly." That would help me out considerably.
I'm about as far from being an engineer as one can get and still live.
(Much to my parents' chagrin.)
>Now, the voodoo. For my purposes, I've found that in uncontrolled
>exterior photography I get about 7 stops difference from the brightest
>highlight to the darkest shadow, and in controlled conditions (like
most >motion picture production sets) I get about 5 stops.
This I don't get at all. Why would one have different latitude depending
on whether one shoots indoors our outdoors? It seems counterintuitive
The film stock should have X amount of latitude regardless of the shooting
situation, if all variables are equal (for example, tungsten light vs.
daylight w/85). The rest of this I'm going to have to sift through more
slowly in order to wrap my head around it. Thank you very much, Andy,
for going into so much detail. I really appreciate it.
One more question :
On Kodak's charts they talk about anything being over 2 1/3 stops above
18% grey as being "overexposure latitude" and anything under
2 2/3's stops below 18% grey as being "underexposure latitude."
I thought over- & underexposure latitude just described how bright
a white or dark a black you could shoot and still see detail. I didn't
realize there were ranges of values. To me that seems to describe a stock
as having a fixed six stop range, with anything beyond being gravy.
Anyone feel like tackling that, or am I opening another can of wriggling
Art Adams, DP
>The film stock should have X amount of latitude regardless of
Latitude is another one of those terms that isn't always used with the
rigour that it should be.
As I was taught, a given emulsion has a certain "useful exposure
range" (effectively, the extent of the straight line portion of the
curve plus a little, or from Andy's MUD point to a similar point near
Typically this might be around 9* stops. (Less on older-style negative
emulsions, less on reversal, MORE on Vision 2). Meanwhile, a given scene
has a "brightness range" measured from the deepest shadow which
you want to register with detail on the negative, through to the brightest
As Andy points out, this may typically be 7* stops in daylight: more in
strong uncontrolled sunlight, less in studio conditions with a lot of
fill. Clearly if the brightness range of the scene is less than the useful
exposure range of the film stock, you can vary the exposure up or down
(by the amount of the difference) and still retain shadow and highlight
detail without crushing or burning. The amount you can vary it is called
Equally clearly, it does depend on the scene brightness
range. Frequently though, it's discussed in terms of an average scene
brightness range. You can use this latitude to overexpose
for a denser negative, thus reducing graininess and stretching shadow
contrast a little, or to get away with under-exposure (a little) when
light is in short supply.
· Bonus tidbit of info:
Every stop is 2:1. So 5 stops of brightness range is 32:1, while 7 stops
is 128:1 and 9 stops is 512:1.
>What follows is a long ramble, but hey, you asked!
Thanks for this Andy, and also for the impressively large guns you wheeled
out to support the bar notation. I was starting to worry when Wade's math
guru denied its existence, but now I feel better.
>mid-way between the bar 2.3 and bar 1.8, or about bar 1.15.
I had to draw a picture to verify this for myself. Correct or not, the
notation sucks! It's a shame this entire thread was on cml-basics, where
it may well have left a few subscribers cold. Never mind picking faults
on Fuji's or Kodak's curves, I think it's been a useful exchange about
the mathematical side of the business. Maybe it'll find its way onto the
>...*bonus tidbit of info: every stop is 2:1.
Another bonus :
When double lighting is used (key and fill), these scene brightness ratios
are multiplied, generally speaking. So if you have a scene range of about
32:1 (the normal reflectance range of most flat surfaces, black to white)
and then light it to a 4:1 ratio, you have effectively raised the brightness
range to 128:1 (4x32).
There will (theoretically) be some white surfaces in the key plus fill
light, but some black surfaces only in the fill. So we scrim the white
objects and punch more fill into the shadows that need detail, effectively
burning and dodging, as in still printing.
Wade K. Ramsey, DP
Art, Dominic, Wade, all,
Thanks, Dominic, for quite ably answering the questions about latitude,
and I couldn't agree more with all of Art's comments on what should be
done to make our graphs more "user friendly."
Trust me, all these posts are getting to the appropriate people.
Oh yeah, I probably should have mentioned specifically that the UV filter
is used to simulate actual shooting conditions because all glass, including
that used in lenses, soaks up UV.
They tell me the corrected characteristics curves should be up on our
web site very soon. I've learned a lot from this thread as well!
>I've learned a lot from this thread as well!
I'm still wading through the math. Dominic was kind enough to resend a
number of his posts; for some reason my Spam killing software thought
he was spamming me. I'm in the process of mental digestion, and swallowing
lots of mental Mylanta.
More questions to come. (Why does that sound so scary all of a sudden?)
Thanks, Andy, Wade and Dominic, very much.
Art Adams, DP
Mountain View, California - "Silicon Valley"
Andy Coradeschi wrote:
>Thanks, Dominic, for quite ably answering the questions about
Thank you and Fuji for the quick response and explanation. Without a network
like CML this probably would have taken months.
What a wonderful resource! But I agree with Dominic--that method of noting
negative Logs is frustrating. I guess a scientist may have a reason to
go through the twisted reasoning required to figure out what the value
really is, but I can't think of one, RIT, et al, notwithstanding! Take
a tip from Kodak....
Anyway, I really appreciate your staying on top of it and getting the
matter straightened out.
Wade K. Ramsey, DP
>I've learned a lot from this thread as well! I'm still wading
through the >math.
Me too!!! I'm suddenly once again considering a career in plumbing!
In the mean time I just figure I'll keep telling myself this all makes
sense and maybe one day it will.