Exposure In Lux Seconds

4th September 2003

I've been wandering through the film spec sections of the cinematography.net site and I'm stumped with the Fuji exposure curve graphs.

How does one translate "Exposure (log H (lux X second)" into camera stops?

I'm looking at the graph in this file :

/Files/F-250.pdf

Kodak finally broke it down into camera stops, which, for those of us who are math impaired, is much easier to understand.

Art Adams, DP
Mountain View, California - "Silicon Valley"
http://www.artadams.net/

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Art Adams wrote :

>…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

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>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.

2) Every (0.5) step on the graph is therefore 1 2/3 stops (not really a useful division for us)

3) 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.

4) 1 lux second (the zero point on the graph) is equivalent to 48 lux at 24fps/180shutter.

5) 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.

7)"H" is what lesser souls call "E" for exposure. D log E curves compare Exposure against density.

Dominic Case
Group Technology Manager
Atlab Australia

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>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

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>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

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>...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

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>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 I look at the Fuji curve on

/Files/F-250.pdf

and compare it with a similar Eastman curve at

/Files/v200t.pdf

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

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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 at them.

Anders "nit picker" Uhl
Cinematographer
New York

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>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

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Dominic wrote:

>...Does anyone on this list understand photometrics?

Telling them apart is one thing, understanding photometrics is another.

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 meter.

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 lux.)

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

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>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

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Dominic wrote:

>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 200T?

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

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>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.

Dominic Case

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>I feel like the Kodak graphs give me that. Are the Fuji graphs different?

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.

Dominic Case

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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 that out.

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 yet.

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

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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 other.

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 around -1.6.

See for yourself :

http://www.fujifilm.com/JSP/fuji/epartners/Products

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

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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

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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 for themselves.

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.

Dominic Case

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>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 things).

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.

Dominic Case

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>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.

Sam Wells

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>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
in footlamberts.

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....

Sam Wells
Do I need to clean the filter & get those old nits out of there ?

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>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

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>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 a change.

Art Adams, DP

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>...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 it.

>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 film.

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 to me.

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 things?

Art Adams, DP

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>The film stock should have X amount of latitude regardless of the >shooting

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 the shoulder.

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 such highlight.

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 the latitude.

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.

Dominic Case

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>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 website.

Dominic Case

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Dominic wrote:

>...*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

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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!

Andy Coradeschi
Fuji-USA

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>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"

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Andy Coradeschi wrote:

>Thanks, Dominic, for quite ably answering the questions about latitude

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

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>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.

Roderick Stevens
Az. D.P.
www.cinema-vista.com

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