Film testing

[Jean Noire]

The point now is that has the discussion helped the originator of the thread in his quest for further understanding of the various systems for establishing exposure control?

Regards
John

 

[Roger Hicks]

The point now is that has the discussion helped the originator of the thread in his quest for further understanding of the various systems for establishing exposure control?

Regards
John

Dear John,

From his PMs, I think so.

Cheers,

R.

 

[Paul Howell]

This thread should be remembered for this fact, insofar as "subject brightness range" is meant to be the brightness of the different constituents of a subject, as seen from the position of the camera.

If the incident reading is taking from the postion of the camera meaning that the dome is facing the subject away from the camera I fail to see how this is acurate reading of the light falling on the subject. I can understand how the meter can be used facing the camera measuring all of the light falling on the subject, full light and shadow to obtain a range.

I guess I can buy the book or a box of paper, I think the box of paper will win out.

 

[sanking]

"A five stop range of reflectance is assumed..."

Why?

The assumption is based on an observation and a deduction. The observation is that when the illumination is uniform on a subject the maximum subject luminance range is rarely greater than 5 stops.

The deduction is that any object that is evenly illuminated (no glare, no shadows) will fit into a 5-stop range, which is 2 stops less than the normal 7 stops.

Davis writes, "it seems logical to assume that the subject luminance range can be estimated by adding the illuminace range, as measured with an incident meter, to the basic subject reflectance range of 5 stops. In practice this works surprisingly well."

In practice the illuminance range is measured by taking two incident readings, one in the shadows where you expect to have some texture, another in the most brightly illuminated area of the scene. You add this value to 5 and you get the subject brightness range of the scene, as it is understood in BTZS terms.

BTW, assumptions are not unique to BTZS and incident systems of metering. ZS is also based on a fair number of assumptions.

I have been using ZS virtually all of my adult life, and BTZS since about 1990. Both methods have their advantages and disadvantages, but on the whole I find BTZS more accurate because it is based on testing procedures that are both more extensive and more precise than the traditional testing procedures of ZS. However, the real beauty of BTZS is that results of the testing, once done, can be used as the basis for using either ZS (reflectance) type metering or BTZS (incident) type metering in real life situations. And this is very useful because there are definitely conditions that are better suited to one or the other of the two systems. For the most part, however, neither system is any more complicated or simple than the other, and regardless of which system one choses to use, the most important decisions we have to make are still creative decisions based on how we want our tonal values to look on the final print.


Sandy King

 

[Jean Noire]

If the incident reading is taking from the postion of the camera meaning that the dome is facing the subject away from the camera I fail to see how this is acurate reading of the light falling on the subject. I can understand how the meter can be used facing the camera measuring all of the light falling on the subject, full light and shadow to obtain a range.

I guess I can buy the book or a box of paper, I think the box of paper will win out.

I think that what mhv had in mind here is the use of a spotmeter from the camera position
Regards
John

 

[symmar_man]

I found that reverse-engineering of the BTZS calculations an enlightening piece of writing. . . all of this discussion has only strengthened my belief in simplicity in my art. . . I understand my simplified ZS approach, thanks to Fred Picker. . .it works just fine for me. . .

I am an engineer and I spend my days pouring over boring equations and graphs every day. . . photography is my escape from this drudgery and I don’t want anything that requires such rigorous engineering any where near me when I do get that precious time to photograph. . . I am so thankful that I had not even heard of BTZS until long after I had honed my photographic skills. . . my photography time is far too precious to even spend one second plotting any curve. . . I know my technique and my materials and they serve me well. . .

It all depends on what you want. . . do you want to be an engineer and think the camera and film to death. . . or do you want to be an artist and create art???. . . that is your choice. . . I have made mine. . . thanks to all here that have only confirmed what I already knew. . . simplicity is the essence of creativity. . .

B Dalton

 

[sanking]

If the incident reading is taking from the postion of the camera meaning that the dome is facing the subject away from the camera I fail to see how this is acurate reading of the light falling on the subject. I can understand how the meter can be used facing the camera measuring all of the light falling on the subject, full light and shadow to obtain a range.

I guess I can buy the book or a box of paper, I think the box of paper will win out.

The incident readings to determine illuminace range are *not* taken with the dome facing the subject. They are taken in the shadows and in the highlights with the dome of the incident meter facing the camera.

Sandy King

 

[Michel Hardy-Vallée]

If the incident reading is taking from the postion of the camera meaning that the dome is facing the subject away from the camera I fail to see how this is acurate reading of the light falling on the subject. I can understand how the meter can be used facing the camera measuring all of the light falling on the subject, full light and shadow to obtain a range.

I guess I can buy the book or a box of paper, I think the box of paper will win out.

Sorry, I think my formulation was ambiguous: the type of meter has nothing to do with the nature of the subject brightness range.

Regardless of how you meter it, a subject is always going to have a certain ratio of light intensities. It is what it is. From the point of view of your camera, it means that there will be different intensities of light reaching your film. The use of an exposure meter (with proper interpretation of its measurement) is just a means to assess the absolute amount of light that will get there.

The incident meter does not give you a direct reading of this range. It gives you a reading of the light falling on the subject, and the BTZS assumes simply, based on statistics, that most of the time, under even illumination, a subject will have 5 stops of brightness range.

Subject brightness range can only be deduced when using an incident meter, while a spot meter will give you actual numbers. The funny thing, as Sandy mentioned, is that the deductive method can work pretty well.

 

[Jean Noire]

I found that reverse-engineering of the BTZS calculations an enlightening piece of writing. . . all of this discussion has only strengthened my belief in simplicity in my art. . . I understand my simplified ZS approach, thanks to Fred Picker. . .it works just fine for me. . .

I am an engineer and I spend my days pouring over boring equations and graphs every day. . . photography is my escape from this drudgery and I don’t want anything that requires such rigorous engineering any where near me when I do get that precious time to photograph. . . I am so thankful that I had not even heard of BTZS until long after I had honed my photographic skills. . . my photography time is far too precious to even spend one second plotting any curve. . . I know my technique and my materials and they serve me well. . .

It all depends on what you want. . . do you want to be an engineer and think the camera and film to death. . . or do you want to be an artist and create art???. . . that is your choice. . . I have made mine. . . thanks to all here that have only confirmed what I already knew. . . simplicity is the essence of creativity. . .

B Dalton

I wholeheartedly agree
Regards
John

 

[Steve Smith]

I am an engineer and I spend my days pouring over boring equations and graphs every day. . . photography is my escape from this drudgery and I don’t want anything that requires such rigorous engineering any where near me when I do get that precious time to photograph. . . I am so thankful that I had not even heard of BTZS until long after I had honed my photographic skills. . . my photography time is far too precious to even spend one second plotting any curve. . . I know my technique and my materials and they serve me well. . .

I totally agree. I am an engineer too and in my spare time I am a musician and photographer. Neither of which need me to sit in front of a computer for hours (like I am now!).

Steve.

 

[Paul Howell]

Sorry, I think my formulation was ambiguous: the type of meter has nothing to do with the nature of the subject brightness range.

Regardless of how you meter it, a subject is always going to have a certain ratio of light intensities. It is what it is. From the point of view of your camera, it means that there will be different intensities of light reaching your film. The use of an exposure meter (with proper interpretation of its measurement) is just a means to assess the absolute amount of light that will get there.

The incident meter does not give you a direct reading of this range. It gives you a reading of the light falling on the subject, and the BTZS assumes simply, based on statistics, that most of the time, under even illumination, a subject will have 5 stops of brightness range.

Subject brightness range can only be deduced when using an incident meter, while a spot meter will give you actual numbers. The funny thing, as Sandy mentioned, is that the deductive method can work pretty well.

This thread started with a disussion of 35mm work, in my case as a former PJ includes backlite and stong side lite subjects which are often moving. Both the ZS and BTZS can be helpful in find a working film speed, but in real life not very helpful. As I stated ealier the folks who BTZS seem to get results my conern is how to apply this system to 35mm. There are several good books on 35mm and ZS, is there is good referance for BTZS for 35.

 

[timbo10ca]

The point now is that has the discussion helped the originator of the thread in his quest for further understanding of the various systems for establishing exposure control?

Regards
John

I've just finished Chp 7 of BTZS (essentially everything to do with film and paper testing, plotting curves, and what the extracted information can tell you). I have to admit that although I had to re-read a couple things after putting it down for a couple hours (Davis left out some reasoning and has some leaps of logic in there), I can say that this book is a brilliant in-depth description of sensinometry, and I see how it is recommended reading. I also see why alot of people don't get through it. I feel that I have a crystal- clear idea on the workings of the film/paper/developer system now (at this book's level, anyway), although it's still a bit fresh to be able to repeat or explain to somebody else. It's like a big intricate 3-D puzzle. I was quite happy to find that as I was reading through his testing chapters, I could say to myself "ah-ha... I see where he's going with this..." I have to say again that reading through Roger's website helped me alot in getting to that point.

I am waiting to see however, like Zone testing, how the BTZS stuff is a personal system, taking meter accuracy, lens, shutter or camera variables into account. I imagine this is in the coming chapters.

BTZS is just exactly that- a method to allow you more intricate control than what the ZS does (wheter it's neccessary for a particular photographer or not). It may be more beneficial for those who are systematic in their approach than those who intuitively know what to do and like to "cook" instead of "bake". Understanding the ZS certainly helps to understand BTZS, as it appears a more basic, "looser" form of control. It's not a different system at all, it's just an extension.

I have observed that you have to be careful as to what type of metering you choose for a particular scene when using BTZS, as it's certainly applicable to both incident and reflective. Personally, I will consider "SBR" to refer to "Subject Brightness Range" when using a spot meter, and "Scene Brightness Range" when using an incident meter, taking on the assumption(s) necessary at that point.

I have decided to write my own book "The Zone Family- Can't We All Just Get Along (Even Those Cousins Who Get On Fine Without Us And Think We're Nuts?)"

 

[jstraw]

It all depends on what you want. . . do you want to be an engineer and think the camera and film to death. . . or do you want to be an artist and create art???. . . that is your choice. . .

Please pardon the philosophical digression but I think that's a false dichotomy based on the assumption that someone that has the stomach for a methodical approach will never take their head out of their navel and get down to work. I think in terms of developing a controllable methodology and then putting it into practice. After which, empirical evidence continues to inform, and sometimes I may decide something new to me requires "study" but basically, I have something that aids me in working smoothly and creatively...not that hinders me.

To use another musical analogy, some people never stop practicing scales and never play out. They develop skills that should aid in facility and improvisation but something keeps them endlessly playing scales. Playing scales isn't the problem. Miles and Bird played countless scales. They just knew when not to.

 

[Michel Hardy-Vallée]

This thread started with a disussion of 35mm work, in my case as a former PJ includes backlite and stong side lite subjects which are often moving. Both the ZS and BTZS can be helpful in find a working film speed, but in real life not very helpful. As I stated ealier the folks who BTZS seem to get results my conern is how to apply this system to 35mm. There are several good books on 35mm and ZS, is there is good referance for BTZS for 35.

I think Tim is also looking into LF. As for 35mm, you can calibrate for N and N- easily, and yield useful results if you shoot under stable light conditions.

 

[Michel Hardy-Vallée]

I feel that I have a crystal- clear idea on the workings of the film/paper/developer system now (at this book's level, anyway), although it's still a bit fresh to be able to repeat or explain to somebody else. It's like a big intricate 3-D puzzle.

You should try reading Grant Haist's "Modern Photographic Processing" if you want the gamma ray super-vision clearitude... I've started it and it's quite readable, but you need some basic real science knowledge to follow him. No leap of logic there, let me tell you, especially when you start from the atomic basis!

Of course, that's still only the intro for the people who actually manufacture photographic materials, but for a layman like me, I'm finally cashing in on the organic chemistry I learned ten years ago.

 

[timbo10ca]

I think Tim is also looking into LF. As for 35mm, you can calibrate for N and N- easily, and yield useful results if you shoot under stable light conditions.

You're right- I will be applying all this new found knowledge mainly to LF, because if I'm going to do it, I'm going to do it "right". I can see how it could be adapted (but with less control) to 35mm and MF. It may not be as good, but it'll be better than what I've been doing so far. I may just apply one of these "less intense" varieties to roll film.

Tim

 

[Michel Hardy-Vallée]

Understanding the ZS certainly helps to understand BTZS, as it appears a more basic, "looser" form of control. It's not a different system at all, it's just an extension.

I told you! Glad to see that I'm not the only one who understand this.

 

[timbo10ca]

You should try reading Grant Haist's "Modern Photographic Processing" if you want the gamma ray super-vision clearitude... I've started it and it's quite readable, but you need some basic real science knowledge to follow him. No leap of logic there, let me tell you, especially when you start from the atomic basis!

Of course, that's still only the intro for the people who actually manufacture photographic materials, but for a layman like me, I'm finally cashing in on the organic chemistry I learned ten years ago.

ummmmm. I think this is enough theory of this type for me.

 

[Chuck_P]

It all depends on what you want. . . do you want to be an engineer and think the camera and film to death. . . or do you want to be an artist and create art???. . . that is your choice. . . I have made mine. . . thanks to all here that have only confirmed what I already knew. . . simplicity is the essence of creativity. . .

B Dalton

I understand what you are saying because it so commonly thought that to do film tesing and finding development times is just so tedious and exhaustive. I could not disagree more, at least from my perspective.

I am comfortably using the ZS and I did not think the camera and film to death. I am not a sensitometrist by any stretch of the imagination, but I did think, evaluate, and ultimately decide. Since I have learned the ZS and am successfully applying it, I am now more free to actually photograph than I ever was before when I did not understand the ZS. I was approximating by trial and error and it was definitely costly in both time and resource. Now that statement I just made is a personal affirmation of this quote by Adams: "Approximation by trial and error is costly in time and resource." That quote just simply nailed me to a "T" when I originally read it. I am currently using my materials more efficiently and one hour in the darkroom now is remarkably more productive than one hour before when I did not know the ZS. Total testing time to establish personal EI's for Plus-X and Tri-X and normal development times, roughly two to three weeks all together I guess and that was while working 5 days a week. I simply decided to do it and I did.

I respect your comments but I reject this notion of rigorous engineering to accomplish the goal.

Regards,
Chuck

 

[Helen B]

...This works conceptually much like Phil Davis' BTZS and is the equivalent of an incident reading, though he uses a reflectance meter. However, the N values for contraction and expansion don't correspond exactly to the SBR values one would derive from sunlight and shadow readings with an incident meter.

Sandy,

I don't have my copy of either BTZS or Minor White's manual handy, but isn't the apparent difference caused by Minor White using an eight zone SBR as normal, while Phil Davis uses seven, and if you take that into account don't they work out to be the same? I'm going from memory, so this could very well be wrong.

Best,
Helen

 

[symmar_man]

I seldom have time to post, but I am an avid reader of this site. . . it keeps me company while I am traveling and have to spend time in a hotel, like now. . . this has been one of the more interesting discussions. . . I have used a few exposure/development systems over the years. . . the first “System” I ever followed and used was The YOB System. . . for those that know about that one, you can guess that I am not a young fellow. . .

I have seen several heated discussions about BTZS vs. ZS and the one group that has never weighed in is the Development By Inspection folks. . . I have never ever considered DBI, but those that I know that use it would use nothing else. . . the DBI folks seem to do no real testing at all. . . they expose some film and if the shadows are not dense enough, they drop their EI by 50% and try again. . . they produce beautiful prints and I see little precision measurement being used with DBI other than a quick eye ball. . . seems to me that if it is possible to produce perfectly printable negatives by eye, why does anyone need all this precision and a computer program???. . . just a thought???. . . kind of like saying you need some sophisticated software to be a painter or sculpture???. . . one last thought. . .

I will check back in 3-4 days when I return to civilization. . . good night all, I have an early flight in the morning. . .

B Dalton

 

[sanking]

Sandy,

I don't have my copy of either BTZS or Minor White's manual handy, but isn't the apparent difference caused by Minor White using an eight zone SBR as normal, while Phil Davis uses seven, and if you take that into account don't they work out to be the same? I'm going from memory, so this could very well be wrong.

Best,
Helen

Helen,

Yes, White does appear to use an eight zone SBR, assuming that the count is made at the transitions of one zone to the next. For a three zone difference White uses N development, where development is presumed to be "normal" at N - 1 1/2.

Sandy

 

[Donald Miller]

I seldom have time to post, but I am an avid reader of this site. . . it keeps me company while I am traveling and have to spend time in a hotel, like now. . . this has been one of the more interesting discussions. . . I have used a few exposure/development systems over the years. . . the first “System” I ever followed and used was The YOB System. . . for those that know about that one, you can guess that I am not a young fellow. . .

I have seen several heated discussions about BTZS vs. ZS and the one group that has never weighed in is the Development By Inspection folks. . . I have never ever considered DBI, but those that I know that use it would use nothing else. . . the DBI folks seem to do no real testing at all. . . they expose some film and if the shadows are not dense enough, they drop their EI by 50% and try again. . . they produce beautiful prints and I see little precision measurement being used with DBI other than a quick eye ball. . . seems to me that if it is possible to produce perfectly printable negatives by eye, why does anyone need all this precision and a computer program???. . . just a thought???. . . kind of like saying you need some sophisticated software to be a painter or sculpture???. . . one last thought. . .

You have addressed another methodology and it is certainly a valid one...perhaps it is good to discuss it at this point.

You are correct that there are and have been some very good photographs produced with this system. There is certainly no arguing with the results that Michael Smith, Paula Chamlee, not to mention Edward Weston obtained. I recently visited with Kim Weston and he told me that he continues to use Pyro and DBI exactly as his grandfather once did. So why do we go to all of the testing? Good question, indeed.

For myself, having used DBI for a period (when I was shooting 12X20) I found that the proper degree of development was difficult to replicate from exposure to exposure. Now that may be due to my aging eyes...or maybe I just did not give it enough time. In the end I gave up on it...just as I did on brush development.

There is a certain appeal to me to keep things simple. It sure makes photography much more intuitive. Furthermore DBI stops the needless and futile ruminations about which approach is best let alone most applicable. I get tired of the discussions of those who have apparently determined how many angels can exist on the head of a pin.

Maybe it is time to revisit DBI...Edward made some images that certainly stand on their own.

 

[MattKing]

There probably is a (yet to be discovered) method that would permit a wise and all seeing sage to, once becoming fully familiar with the strengths and talents of any photographer, recommend to that photographer the one, single method they should use at that time to maximize the quality of their work.

I have no doubt, however, that in order to be truly wise and all seeing, that sage would have to be able to recommend different methods, to different photographers.

I expect, as well, that some photographers would benefit from one recommendation at one stage of their experience, and benefit as well from another recommendation later.

The things I have taken from this thread are:

1) in order for any system to work for a photographer (including me) the photographer must understand it well, and be familiar with its inherent assumptions and peculiarities;
2) different systems will better suit some temperaments and approaches;
3) a method and a consistent approach, well understood and well suited to the strengths of the particular photographer, will help the photographer realize the most from his/her creativity; and
4) if your system of choice isn't working for you, make sure first that you are understanding it properly, and applying it properly, and if so, and it's still not working for you, consider trying something new.

Finally, I expect a truly rewarding experience would be to be in the presence of Donald, and Roger, and Sandy and a whole bunch of the other passionate contributors to this thread, and to observe them using the approaches that work for them, as they create photographs that work for them, and for others.

Matt

 

[Jean Noire]

I seldom have time to post, but I am an avid reader of this site. . . it keeps me company while I am traveling and have to spend time in a hotel, like now. . . this has been one of the more interesting discussions. . . I have used a few exposure/development systems over the years. . . the first “System” I ever followed and used was The YOB System. . . for those that know about that one, you can guess that I am not a young fellow. . .

I have seen several heated discussions about BTZS vs. ZS and the one group that has never weighed in is the Development By Inspection folks. . . I have never ever considered DBI, but those that I know that use it would use nothing else. . . the DBI folks seem to do no real testing at all. . . they expose some film and if the shadows are not dense enough, they drop their EI by 50% and try again. . . they produce beautiful prints and I see little precision measurement being used with DBI other than a quick eye ball. . . seems to me that if it is possible to produce perfectly printable negatives by eye, why does anyone need all this precision and a computer program???. . . just a thought???. . . kind of like saying you need some sophisticated software to be a painter or sculpture???. . . one last thought. . .

I will check back in 3-4 days when I return to civilization. . . good night all, I have an early flight in the morning. . .

B Dalton

I'm not sure that DBI would be practical with today's 35mm or roll film. What safe light is useable? These films are pretty small to assess under dim light and high speed film may be ruled out altogether.
So, as has been said already, it seems a matter of "horses for courses".

Regards
John