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
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.
"A five stop range of reflectance is assumed..."
Why?
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.
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.
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 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 dont 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 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 dont 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. . .
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.
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
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. . .
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 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 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.
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.
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.
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
...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
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.
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
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