Film testing

timbo10ca · Feb 10, 2007

jstraw said:
Where?

www.circleofthesunproductions.com

jstraw · Feb 10, 2007

Thanks Tim.

Allen Friday · Feb 10, 2007

Chuck1;429813I would argue that changing the EI when + or - development is planned is incorrect if the ZS is being applied. All in the interest and love of the "wet process". Regards Chuck[/QUOTE said:
Hello Chuck,

Ansel Adams explains what I was refering to much better than I. Please see my post above in this thread, it is number 39, where I quote Adams and for a description of adjusting exposure based on + or - development.

Thanks,

Allen

Donald Miller · Feb 10, 2007

Allen Friday said:
Congratulations Donald,

You have now conclusively proven, once and for all, that when it comes to the zone system, you are totally incompetent. You do not understand it, and what is worse, your lack of understanding is so great that you cant even consider the possibility that you dont get it.

Donald, if I take a zone I reading and place it at zone I on my meter I will get exposure X. If I take a zone II reading and place it at zone II on my meter I will get exposure X. If I take a zone III reading and place it on zone III I will get exposure X. If I take a zone IV reading and place it on zone IV on my meter I will get exposure X. If I take a zone V reading and place it on zone V of my meter, I will get exposure X.If I take a zone IX reading and place it on zone IX, I will get an exposure X.

Basing exposure on any zone does not change the EI of the film. I am not doubling or giving 2 ½ stops change to the film speed like you said in your first post. The EI stays the same. The only time EI is changed is if + or - development is called for, and then the EI is adjusted to compensate.

From now on, whenever you jump in with your attacks on the zone system, I am going to refer readers to this thread. Anyone who has even a cursory knowledge of the ZS will be able to judge the weight to give your writings.

Ad Hominem attacks will be referred to this thread as well.

Chuck_P · Feb 10, 2007

Allen Friday said:
Hello Chuck,

Ansel Adams explains what I was refering to much better than I. Please see my post above in this thread, it is number 39, where I quote Adams and for a description of adjusting exposure based on + or - development.

Thanks,

Allen

Allen,

I see what you meant now and yes I have that whole section highlighted in my book. I think we are on the same page on this issue---I was wandering if I had missed the boat on something and then maybe sounded a bit too confident in my post to you; just a friendly challenge to your assertion. I use n+1 and n-1 one development for my EI of 64 for Plus-X and normal development time of 4:30 sec at HC-110 1:63 from conc. However, I have not seen the need to make that exposure adjustment for my negatives at either N+1 or N-1. I interpert p. 223 last paragraph before "Local Contrast" to mean that those adjustments are most crucial at N+2 and N-2 development times. Perhaps I'm wrong, but my negatives don't indicate a need for that adjustment. And that seems to make sense to me because N+2 would be about a 100% increase in development time, which could certainly cause increased density in the middle and low values where it may not be desired.

Chuck

Allen Friday · Feb 10, 2007

Hi Chuck,

As Ansel says, his adjustment guidelines are only rules of thumb and should be verified by testing. Some film/devloper combinations require much more adjustment than he says, some combinations don't require any. All this stuff is pretty much common sense once one gets past all the technical jargon.

By the way, I like your statement, "All in the interest and love of the 'wet process'."

Allen

Donald Miller · Feb 11, 2007

Roger Hicks said:
"If this is difficult to comprehend, you might avail yourself of Phil Davis latest book on the subject."

Dear Don,

Please do not attempt to patronize me until you know more about the subject and have thought it through.
Go through the thought experiment I described in my last post, and tell me how the incident light meter can tell whether it is in front of the black velvet on white snow, the white snow alone, the black velvet alone, or a normal scene.

Then tell me how you are measuring the subject brightness range with an incident light meter.

To turn your own words back on yourself, you find this difficult to comprehend, you might try thinking instead of parroting. Oh -- and if you try measuring black velvet on snow, you'll find that depending on the angle of the plush, the type of snow and the angle of the sun, it can exceed five stops; I've tried it. I'm not sure it can reach six stops, but this doesn't affect the argument.

I hate to appear rude, but really, I do have some idea of what I am talking about, and even if I didn't, as I say, the thought experiment will demonstrate clearly that you are wrong.

Cheers,

R.

Roger, Please understand that I would never attempt to patronize you... I was simply suggesting that you may want to read some additional material. I suggested this since you seem to have difficulty accepting anything that falls external to the self constructed box of your beliefs.

Now on to your question. The dome of the incident meter is designed to give the average of the luminance falling on a typical subject or scene. The large variance is not the degree of reflectance as most are wont to believe but rather the variance of the incident light falling upon the subject or scene. A case in point would be something that is shaded versus sunlit. When we subtract the differences in incident light (low values from high values) then add that value back to the factor of the dome, we have the subject brightness range. I hope that I have conveyed to you in an understandable way how the subject brightness range is capable of being measured with and incident meter. If you have further questions, please feel free to pose them.

Now I really could care less if you want to continue to believe what you believe. However, please understand, that I do extend to myself the same liberty that I extend to you. I would hope that in the interest of fairness, mature interaction, and lack of ego gratification on everyone's part that you would extend this same liberty to me. Fair enough?

Having said this I would sincerely hope that I have succeeded in recognizing and validating your human dignity while seeking to act in a mature, sensible, and sensitive manner.

Donald Miller · Feb 11, 2007

Allen Friday said:
Congratulations Donald,

You have now conclusively proven, once and for all, that when it comes to the zone system, you are totally incompetent. You do not understand it, and what is worse, your lack of understanding is so great that you can’t even consider the possibility that you don’t get it.

Donald, if I take a zone I reading and place it at zone I on my meter I will get exposure X. If I take a zone II reading and place it at zone II on my meter I will get exposure X. If I take a zone III reading and place it on zone III I will get exposure X. If I take a zone IV reading and place it on zone IV on my meter I will get exposure X. If I take a zone V reading and place it on zone V of my meter, I will get exposure X….If I take a zone IX reading and place it on zone IX, I will get an exposure X.

Basing exposure on any zone does not change the EI of the film. I am not doubling or giving 2 ½ stops change to the film speed like you said in your first post. The EI stays the same. The only time EI is changed is if + or - development is called for, and then the EI is adjusted to compensate.

From now on, whenever you jump in with your attacks on the zone system, I am going to refer readers to this thread. Anyone who has even a cursory knowledge of the ZS will be able to judge the weight to give your writings.

Allen,

After taking several hours digesting your venomous and vitriolic diatribe and taking the time to discuss this with the moderators of this forum, I wanted to take this opportunity to respond to your demeaning and abusive comments.

First let me assert that I am mature and I would hope that you would be mature enough at some point to discuss our differences without personal affronts or attacks. Yet, in my experience with you, consistantly and ongoingly I seem to experience the latter from you. These personal attacks do nothing other than to indicate a poorly formed character that is incapable of factual discussion of viewpoints or opinions without degenerating into abusive claims, statements or assertions.

Having said that. If you will take the time to reread what I stated you will see that I was saying that placing a shadow placement above Zone I would have the same effect as lowering the EI of a given film. (An exposure of Zone I at the given EI would be the same exposure as Zone III at 1/4 of that same EI). Take the time and think this through if you are interested in a mature discussion. I think that if you will do that without engaging your verbalization for a minute you will see that my assertion is factually correct. Having said that, your apology is in order.

Chuck_P · Feb 11, 2007

I wonder what old AA would say to all this discussion about the ZS. When asked by John Sexton what he thought his epitaph should read, AA responded that it might be similar to what Alfred Eisenstadt wanted his to read which was:

"Here lies Alfred Eisenstadt, he lived for better or for worse but he's dead for good."

I think AA would say of the ZS: the zone system, it exists for better or for worse, but it is alive and well.

I'm smiling as I write this and I say that I think the overall discussion that we are having is a healthy one for what we do. Albeit, the form of communication, however, presents it own set of difficult circumstances to overcome.

Chuck

Allen Friday · Feb 11, 2007

Reply to Donald Miller-1

Donald,

I am sorry. I am sorry that you dont get it. I will quit responding to your ridiculous attacks on the zone system when you quit making them. Again I have to ask why you feel compelled to respond to zone system threads in the first place. I thought that you were capable of learning after our discussion on visualization when you quit posting on zone threads for a while. I see I was mistaken. If you continue to post misinformation on the zone system, I will continue to respond.

I stand by my statement that you do not understand the zone system and that you are clearly demonstrating it in this thread.

As for your math, it is to a certain extent correct. Imagine that your grand child comes in and says he has two apples and three oranges. He then wants to know how many pieces of fruit he has. Six you would say. Two times three is six. Well, your math is correct in that 2 times 3 is 6. But it is wrong here because you should have added, not multiplied.

Your math as applied to the zone system is likewise partly correct. If you are discussing the relationship between film speed and aperture and shutter speed , then a two stop change in one would dictate a two stop change in one of the others. For you, moving from zone V to zone III is a two stop change and therefore the EI (film speed) must change two stops. The problem here, Donald, is that you are multiplying when you should be adding. What you dont get is that with a normal scene, taking a zone 3 reading and placing it on zone 3 will call for the same exposure (aperture and shutter speed) as taking a zone v reading and placing it on zone v. Since you are not changing the aperture or shutter speed, then you do not make any adjustment to the EI. Your calculation of a two stop change is not needed and is misapplied.

Allen Friday · Feb 11, 2007

Reply to Donald Miller -2

Second, you fail to realize the absolute basics of zone system metering. In your post #48, you state, Think about it this way if you will...why would someone arrive at a film exposure that evidences a .10 density above FB+fog and then effectively reduce that EI by two more stops (Zone III exposure)? If the film needs two stops more exposure (Zone III exposure again) than the first value wouild seem to be inadequate in practice. Perhaps you can come up with a reason for doing this...I can't come up with a good reason...the exposure at the determined EI at that EI is either adequate or it is not.

What you fail to grasp Donald is metering 101, how the meter see the subject and what that reading tells you. A spot meter or other reflective meter will average the area in the scene from which it receives light. The reading the meter provides will be correct if, and only if, the scene is average, or it has the same amount of lights as it does darks. Ill explain this more for you Donald, as it is crucial.

Lets take it out of the zone system for a moment so that you can see that the principles work across all photography, not just the zone system. Suppose you take a Cannon AE1 up to Flagstaff to photograph the ski slopes. You use 400 speed color negative film at EI 400. When you arrive at the slopes, you point your camera at a hill side covered with snow and one skier in the distance. If you blindly follow the cameras meter reading what will happen? The exposure will be off by 2 or 3 stops. Why? Because the meter wants to render a scene that is mostly white as a middle grey. To compensate, you would take your meter reading and then adjust 2 or 3 stops. What happened to your film speed here? Nothing, nada, zero, no change. Why, all you were doing was adjusting from the exposure indicated on the meter to one that would make the white snow come out white, and not grey, in the final print.

Lets take another example. Suppose on the same trip to Flagstaff, you took your Leica MP, which doesnt have a meter, and you used it with an incident meter. You meter from the porch of the lodge, which is in the shade. The ski slope is in the sun. Will the indicated meter reading taken in the shade work for the sunlit slope--nope. You will have to adjust your exposure by 2 or 3 stops from the indicated exposure. What happens to the EI or film speed here? Nothing, nada, zip, zero. Why? Because again you are only adjusting from the indicated reading on the meter to one which will give you the correct exposure at that film speed.

So now Donald, lets go back to the zone system. I want to take a zone three meter reading. I pick out a shadow area where I want detail in the final print. I point my meter at the spot and take the reading. Suppose the reading is 125 @ f16. I will then adjust it two stops to give me the zone three reading. Why? Because the 125 @f16 is the reading I would use to make the shadow area of the scene appear middle grey in the final print. I dont want it to be middle grey, so I adjust the exposure 2 stops, so that the shadow in the scene will turn out zone three on the final print.

Now Donald, here is the really important part--the part you are missing--125 @f16 is not my zone v exposure. No Donald, it is not. Why, because that exposure would render the shadows as a middle tone on the print, not the middle tone from the scene. My zone V exposure, in a normal scene would be the same as my zone 3 exposure.

And what happens to the EI or film speed in adjusting from the indicated exposure on the meter to one which will render the tones they way we want them? The same thing that happened in our two examples above: nothing, nada, zip, zero, nichts. It doesnt change, Donald.

Taking a spot reading and placing that reading on the appropriate zone is fundamental to the zone system. If, in a normal scene, you think that reading a zone 3 portion of the scene and placing it on zone 3 will lead to a different exposure than taking a zone 5 reading and placing it on zone 5, you are just flat wrong. It is an absolute fundamental to the zone system. If you dont get this, then you obviously dont understand the zone system.

Donald Miller · Feb 11, 2007

Allen Friday said:
Reply to Donald Miller -2

Second, you fail to realize the absolute basics of zone system metering. In your post #48, you state, “Think about it this way if you will...why would someone arrive at a film exposure that evidences a .10 density above FB+fog and then effectively reduce that EI by two more stops (Zone III exposure)? If the film needs two stops more exposure (Zone III exposure again) than the first value wouild seem to be inadequate in practice. Perhaps you can come up with a reason for doing this...I can't come up with a good reason...the exposure at the determined EI at that EI is either adequate or it is not.”

What you fail to grasp Donald is metering 101, how the meter see the subject and what that reading tells you. A spot meter or other reflective meter will average the area in the scene from which it receives light. The reading the meter provides will be correct if, and only if, the scene is average, or it has the same amount of lights as it does darks. I’ll explain this more for you Donald, as it is crucial.

Lets take it out of the zone system for a moment so that you can see that the principles work across all photography, not just the zone system. Suppose you take a Cannon AE1 up to Flagstaff to photograph the ski slopes. You use 400 speed color negative film at EI 400. When you arrive at the slopes, you point your camera at a hill side covered with snow and one skier in the distance. If you blindly follow the camera’s meter reading what will happen? The exposure will be off by 2 or 3 stops. Why? Because the meter wants to render a scene that is mostly white as a middle grey. To compensate, you would take your meter reading and then adjust 2 or 3 stops. What happened to your film speed here? Nothing, nada, zero, no change. Why, all you were doing was adjusting from the exposure indicated on the meter to one that would make the white snow come out white, and not grey, in the final print.

Lets take another example. Suppose on the same trip to Flagstaff, you took your Leica MP, which doesn’t have a meter, and you used it with an incident meter. You meter from the porch of the lodge, which is in the shade. The ski slope is in the sun. Will the indicated meter reading taken in the shade work for the sunlit slope--nope. You will have to adjust your exposure by 2 or 3 stops from the indicated exposure. What happens to the EI or film speed here? Nothing, nada, zip, zero. Why? Because again you are only adjusting from the indicated reading on the meter to one which will give you the correct exposure at that film speed.

So now Donald, lets go back to the zone system. I want to take a zone three meter reading. I pick out a shadow area where I want detail in the final print. I point my meter at the spot and take the reading. Suppose the reading is 125 @ f16. I will then adjust it two stops to give me the zone three reading. Why? Because the 125 @f16 is the reading I would use to make the shadow area of the scene appear middle grey in the final print. I don’t want it to be middle grey, so I adjust the exposure 2 stops, so that the shadow in the scene will turn out zone three on the final print.

Now Donald, here is the really important part--the part you are missing--125 @f16 is not my zone v exposure. No Donald, it is not. Why, because that exposure would render the shadows as a middle tone on the print, not the middle tone from the scene. My zone V exposure, in a normal scene would be the same as my zone 3 exposure.

And what happens to the EI or film speed in adjusting from the indicated exposure on the meter to one which will render the tones they way we want them? The same thing that happened in our two examples above: nothing, nada, zip, zero, nichts. It doesn’t change, Donald.

Taking a spot reading and placing that reading on the appropriate zone is fundamental to the zone system. If, in a normal scene, you think that reading a zone 3 portion of the scene and placing it on zone 3 will lead to a different exposure than taking a zone 5 reading and placing it on zone 5, you are just flat wrong. It is an absolute fundamental to the zone system. If you don’t get this, then you obviously don’t understand the zone system.

O.K. Allen since you have decided that I am flat wrong, as you put it, I am not at all sure that you are open to seeing things apart from what you decided at the outset...but let me again address what I said and why what you are saying is like comparing the apples and oranges that you mentioned in your response.

For just one moment put your judgements aside, if you can, and listen to what I am saying.

I am saying that the common practice of using the Zone system is that most practitioners are placing the shadow exposure value on a Zone III placement. Some go as high as a Zone IV placement. Nowhere have I mentioned Zone V or what the meter tells us. I assure you that I understand the Zone System and used it effectively for over twenty years. I don't use it any longer for valid personal reasons. Whether you use it or not is of none of my concern.

My posts have clearly stated that by placing the shadow exposure at Zone III or IV has the same effect as reducing the EI of the film by two or three stops...period..end of tale. You make up all of the rest that you think that I have said in your mind.

My math is accurate. Everything else that you are wont to do to discredit me is of no consequence at all. My question is simply this and nothing more. Is my math accurate? No other answers are asked for, required, or merited.
Do the math yourself...Zone III at EI 125 will give the same effective exposure as Zone I at EI 32. If it doesn't then I will eat my damned hat...(that would mean buying one since I don't wear the damned things)

I do have one other question...why the hell do you take everything so damned personal...I have not addressed your level of expertise in any area of your photography or of any other area of your life. Why, I wonder, do you have such a diminished view of yourself that everything impacts upon you?

Allen Friday · Feb 11, 2007

Donald,

I see you are doing it again. You make some ridiculous post about the zone system based on a misunderstanding of the system. When it is pointed out that what you said is complete crap, you retreat and say that that isn't really what you meant. You use statements like "all I meant was this” or if you reread my post you’ll see I meant this…” I can’t read you mind Donald. I base what I say on what you write the first time, not the way you amend it.

In your post number 54 you state, “ they seem to universally place at either a III or IV for their shadows. That still is two or three stops more exposure than the film tests indicated. More exposure translates to a lower effective EI in my book.” What does the sentence “That still is two or three stops more exposure than the film test indicated” supposed to mean, other then it would require two or three stops more exposure than the film test indicated. If that is not what you wanted to say, then you shouldn’t have said it.

The key point here is that taking a zone three reading does not as you stated mean that the film is given “two or three stops more exposure than the film test indicated.”

As I have been saying all along here, and you have never even discussed, when you have a normal scene, taking a zone one meter reading will give you exposure X, taking a zone three meter reading will give you exposure X, taking a zone V meter reading will give you exposure X. All three give you the same exposure. The EI, or the speed the film test indicated, does not change. So Donald, go buy a hat and some Tabasco sauce.

Well Donald, I am done now. I do not discuss these matters with you to try to convince you that you are wrong. I know that is impossible. You would have to be open enough to consider the possibility that you could be wrong. I enter into these discussions with you so that others who read this can decide who is right. I have shown that the EI does not change, as you say. Anyone reading this can judge.

Donald Miller · Feb 11, 2007

Allen,

You have proven, once again, that in order to have a dialogue of merit that several things are required...chief among them is a willingness to resolve an issue...second most is the intellect to reason. I am sorry to say that by virtue of what you have written you fail on two scores...I am putting you on my ignore list...I would appreciate the same from you.

Roger Hicks · Feb 11, 2007

Donald Miller said:
Roger, Please understand that I would never attempt to patronize you... I was simply suggesting that you may want to read some additional material.

Having said this I would sincerely hope that I have succeeded in recognizing and validating your human dignity while seeking to act in a mature, sensible, and sensitive manner.

Dear Don,

I apologize if I appeared unduly thin-skinned, but "I wonder if you understand incident light metering" and "If you find this difficult to comprehend" and "self constructed box of your beliefs" sound pretty damn' patronizing to me.

I have been studying photography for some 40 years now. I own and have read an inordinate number of books on the subject, and I have had the privilege of discussing these topics with experts far greater than I, including a member of the ISO standards committee. My more recent books on this and related subjects were read at draft stage by some of these experts, again including my chum on the ISO standards committe. They did not find the errors that you seem to find. If I were quite as ignorant as you seem to think, how many books would I have had published, and why would I be one of the better regarded journalists in this field?

The simple truth is that you are wrong. Worse, you are wrong in obfuscatory language. I have tried to refrain from being offensive in saying so, but I can sympathize with others who have not been so restrained. What you characterised as an ad hominem attack by Allen was not: it was an attack (quite well justified) on your extremely wobbly interpretation of the Zone System. He did not say, "Don is an evil man who tortures kittens and eats babies and therefore cannot be trusted on this subject or any other" or even, "Don is a cretin who can't tell his arse from his elbow and therefore etc." What he said, admittedly in strong language, is that "Don is a man whose understanding of the Zone System is shaky in the extreme." No-one here with a grasp of basic sensitometry seems to disagree with him.

Quite honestly, I can't be bothered to try to sort out some of your statements. When someone asserts that you can measure brightness ranges with an incident light meter, his grasp of the terms 'measure' and 'brightness range' is clearly tenuous. I have explained in other posts how you get away with this sloppy and indeed meaningless approach, with, I hope, a clarity that is often missing in your own posts.

Just as you do not care what I believe, I do not care what you believe -- until you confuse others by saying things that are flatly wrong, such as your assertion that you can measure SBR with an incident light meter. For the last time I invite you to look at the thought experiment I proposed in my original post, and tell me how the meter knows what is behind it.

Cheers,

Roger

Allen Friday · Feb 11, 2007

Donald,

I consider it an honor to join the other fine Apug members who comprise your ignor list.

Jean Noire · Feb 11, 2007

Donald Miller writes -

"A case in point would be something that is shaded versus sunlit. When we subtract the differences in incident light (low values from high values) then add that value back to the factor of the dome, we have the subject brightness range."

How on earth can we know what the subject brightness range is without measuring the subject?

Sorry but completely confused me on this one.

Regards

John

Roger Hicks · Feb 11, 2007

jonjonho said:
Sorry but completely confused me on this one...
John

Dear John,

That is because it is complete nonsense.

Cheers,

R.

BBarlow690 · Feb 11, 2007

Quick note to Roger re: your half-day/densitomer comment long ago in this thread:

The main point of my kit is that it eliminates the need for a densitometer. It lets you calibrate materials in the way that you use them.

And a half day includes drying time. Five minutes to expose a film speed test. Develop negs and read them with tools supplied - voila! Accurate ISO for any film/developer combination.

Five more minutes to expose development time negs at just-established ISO. Develop. These need to dry, so I go watch grass grow, and most of the half day progresses. When dry, or dry enough, go into darkroom, establish Proper Proof exposure (five minutes), and expose test negs. Voila - one of them will have proper development.

I can calibrate to any paper (Azo was a challenge, but done), any contrast grade (2 for LF, 3 for 35mm for a shorter development time and less grain), and any paper developer. I can calibrate for N+1, N+2, N-1, etc.

The kit is infintely reusable as long as you don't lose it, which in my darkroom with my personal habits represents a risk. For me, though, I'd rather make pictures than do tests.

www.circleofthesunproductions.com. Check out the free downloads of the paper/developer tests. Those who didn't see them in View Camera magazine three years ago may find them interesting. After you read them you'll understand why I don't enjoy testing anymore (not sure I ever enjoyed it).

Roger Hicks · Feb 11, 2007

BBarlow690 said:
Quick note to Roger re: your half-day/densitomer comment long ago in this thread...

Your kit certainly looks clever, and I have no doubt that it will suit many people. To a considerable extent, you and I are singing from the same hymn sheet: there's an awful lot of needless complication. It's so long since I internalized most of this stuff that I'm not sure whether, if I were starting out today, I'd buy your kit. I probably would, because it's so admirably unpretentious and realistic. Put it this way: at that price, and with that timescale, pretty much anyone can afford to find out whether or not they're happy with it. Unlike most Zone books and tests...

Actually, I might recommend a two-pronged approach to the beginner: my simple iterative test with real pictures, plus yours if they want something that doesn't depend on recognizing a good print to begin with.

Cheers,

R.

jstraw · Feb 11, 2007

Donald,

Did you understand what I was saying in post #62?

Roger Hicks · Feb 11, 2007

Shameless self promotion

I've just realized that I should have done this long ago in this thread. In the Photo School at www.rogerandfrances.com, there are at least three free modules that may be of use. One is on ISO speeds: what they are, what they mean, and why it's often a good idea to use EIs instead. Another is on subject brightness ranges and their relevance to film development. The third is on density, gamma and the H&D curve. Perhaps I should simply have referred people to these rather than repeating so much...

Obviously I hope that people (except perhaps Donald) will find the free information so useful that they decide to subscribe as well, but if not, well, it's all traffic.

Cheers,

R.

timbo10ca · Feb 11, 2007

I just hope this thread doesn't get locked and hidden somewhere, so I can refer back to it when needed

Donald Miller · Feb 11, 2007

Roger Hicks said:
Dear Don,

I apologize if I appeared unduly thin-skinned, but "I wonder if you understand incident light metering" and "If you find this difficult to comprehend" and "self constructed box of your beliefs" sound pretty damn' patronizing to me.

I have been studying photography for some 40 years now. I own and have read an inordinate number of books on the subject, and I have had the privilege of discussing these topics with experts far greater than I, including a member of the ISO standards committee. My more recent books on this and related subjects were read at draft stage by some of these experts, again including my chum on the ISO standards committe. They did not find the errors that you seem to find. If I were quite as ignorant as you seem to think, how many books would I have had published, and why would I be one of the better regarded journalists in this field?

The simple truth is that you are wrong. Worse, you are wrong in obfuscatory language. I have tried to refrain from being offensive in saying so, but I can sympathize with others who have not been so restrained. What you characterised as an ad hominem attack by Allen was not: it was an attack (quite well justified) on your extremely wobbly interpretation of the Zone System. He did not say, "Don is an evil man who tortures kittens and eats babies and therefore cannot be trusted on this subject or any other" or even, "Don is a cretin who can't tell his arse from his elbow and therefore etc." What he said, admittedly in strong language, is that "Don is a man whose understanding of the Zone System is shaky in the extreme." No-one here with a grasp of basic sensitometry seems to disagree with him.

Quite honestly, I can't be bothered to try to sort out some of your statements. When someone asserts that you can measure brightness ranges with an incident light meter, his grasp of the terms 'measure' and 'brightness range' is clearly tenuous. I have explained in other posts how you get away with this sloppy and indeed meaningless approach, with, I hope, a clarity that is often missing in your own posts.

Just as you do not care what I believe, I do not care what you believe -- until you confuse others by saying things that are flatly wrong, such as your assertion that you can measure SBR with an incident light meter. For the last time I invite you to look at the thought experiment I proposed in my original post, and tell me how the meter knows what is behind it.

Cheers,

Roger

Roger, I have tried to be reasonable in my explanation to you. But this most recent post of yours is a bit over the top.

I have tried to convey to you the means by which I and a large number of others can and do measure SBR by using an incident light meter. You take exception when I factually state that your knowledge in this area is limited...that resources do exist to allow you understand. Furthermore I have tried to explain to you that given your contentious and narrow viewpoint you are unlikely to ever gain an understanding of why and how this works. You persist in thinking in terms of reflective measurements and that leaves me no other alternative than to believe that there are none so blind as those who simply will not see.

That leaves me at a loss of what more I can do...considering that you apparently find it difficult to learn anything more since in your arrogant way you seem to think that you know it all.

So considering that, I guess that you and I must agree to disagree

Roger Hicks · Feb 11, 2007

Donald Miller said:
...that leaves me no other alternative than to believe that there are none so blind as those who simply will not see.

Dear Don.

We certainly agree on this.

I find it interesting that while a number of people have suggested that you might be wrong, absolutely no-one has suggested you may be right.

This leaves two possibilities. One is that your stellar intelligence has left the rest of us in the dust, despite the somewhat opaque manner in which you phrase your assertions. The other is that you may indeed be completely wrong. For obvious reasons -- not least logic -- I incline towards the latter.

Why do you persistently refuse to point out the flaw in my original thought-experiment about the incident light meter in front of (a) snow (b) black velvet (c) a mixture of the two? Can it be that there is not one? And that you are simply wrong? Which of us, indeed, is demonstrating arrogance here, and a refusal to learn?

IF you can demonstrate the flaw in that thought-experiment, I (and many others) will be grateful, and we shall have learned a great deal. If you cannot, we are entitled to dismiss your arguments that you can in fact measure (not approximate, not guess, not assert) the brightness range of a subject using an incident light meter.

By the way, despite your assertion, I do not claim to 'know it all'. Many know a good deal more than I about this subject. Alas, you are not among them.

Cheers,

R.

Film testing

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