BTZS + Modern Incident Meter w/ Digital Readout

[jcoldslabs]

Bill,

I figure consistency is as good a plan as any. I use the same old shutters all the time, so the slow speeds are built into my process, the same old uncalibrated meters, the same developer and dilution, and I develop with some temperature and agitation sloppiness built in so my results are targeted with a range, not to the furthest decimal place. Bullseyes are great, but like you I am content with hitting the board and adjusting my aim as I go.

But to be clear: I have great admiration for those who refine their processes and routinely test until they achieve the results they want. I have seen prints from nearly perfect negatives (a subjective term, I know) that blow me away. I know my work will never get there, but I have made peace with that fact.

Jonathan

[Shen45]

There is an expression about a committee designing a horse and ending up with a camel and so it seems from most people that have only read the BTZS book but never used the "system". BTZS is not the Zone system. It is similar but oh so superior in many ways. I find it refreshing that Ken is actually setting out with the intention of using the system as designed. I've used BTZS for about 7 years now and initially just reading the book was "challenging" to say the least, however when I put aside preconceived ideas and practices from my past things started to make sense. I forked out for all the software, a densitometer and the processing tubes. I had to learn the methodology, the terms and accept what I felt may have been short comings of the system as a whole. The short comings were more mine though due to trying to use the system in ways contrary to its designers intent.

If you choose to go BTZS with the lot then you will need to set up your darkroom with the ability to test your film according to the requirements of the system. No other test data or method will work - for BTZS. It is an integrated system.

The Plotter program requires a known standard and that [for me] was/is based on Delta 100 processed in D76. Phil Davis lists both Delta and Tmax 100 as reaching a genuine 100 iso.

The requirements for calibrating your own enlarger for your personal speed point may take an afternoon but is only done once. This calibration step accounts for your enlarger, timer, thermometer and agitation. You expose film in contact with a step wedge and read that into the plotter program. For the PSP test 3 sheets are exposed using an accurate repeatable digital [preferably] timer and then processed for 4, 8 and 16 minutes. The step wedges are then analysed by the plotter program to determine what your PSP is. If the PSP value you get from your set up matches the figure Phil has determined your testing standard has been established. If not the BTZS site has simple instructions to get it all set correctly. Once determined you will have an EV reading of your enlarger light source and a PSP number for the plotter program.

Once you have your PSP determined ---

The premise of BTZS is tying everything back to the media you are going to print on. About 2 hours testing of your paper will determine the actual grades of the paper and an "ES" value that will be used by the plotter program when you create an exported file for the Palm or the new iOS version of ExpoDev. Your paper testing must be done using the actual enlarger or light source you use for printing.

To test your actual film, set the EV of your enlarger to the one you determined with your initial test adjusted up or dawn to account now for the boxed speed of the film you are testing. EG if the 100 iso standard requires EV4 then a 200 iso box speed film will require the enlarger to be adjusted to EV3 for the series of step wedges.

Five sheets are exposed identically and then processed at 4, 5:40, 8, 11 and 16 minutes. You can if you wish increase the 16 minute time to 20 minutes if your developer is capable of sustained development to that time and that can sometimes give you a greater range from the film you are testing. D76 is one developer that can easily develop to that time without the resultant film curve becoming misshaped due to developer exhaustion. The results are read into the plotter and your testing is basically completed. The plotter analyses the wedges and sets the point of darkest texture and based on your tested ES value the brightest highlight with just visible texture. The plotter sets other important points of course including the speed that your film has tested at. From a very small amount of effort you now have a collection of data including the SBR [range] of your film. Times temperatures and film speeds. Zones and more. A file can now be exported to your mobile device with the ES applied for your paper grade you want to print on.

BTZS testing will very quickly show you what a film/developer combination can and cannot handle. BTZS testing will only give you useful data within what the film/developer combination can be expected to produce high quality easily printable negatives. If your light conditions in the field exceed your test results ExpoDev will tell you you have exceeded the capabilities of the film.

BTZS allows you to use either Incident or spot metering, I use both, and both work equally as well. Both can be used for "creative" placement of tones within the range of your tested film. Both have their own particular limitations in any type of photography but these are minor and once metering experience is gained with the system both work equally as well.

There appears to be a basic lack of understanding of what BTZS really is on this and other fora, BTZS is not the Zone system. It is similar but oh so superior in many ways. it is a complete system of testing exposure [factors, bellows, reciprocity and individual sheet development times]. The learning curve initially is a bit steep but it is soon forgotten and becomes an automatic part of your photographic arsenal. BTZS has bucket loads of info for the photo geek but if figures bore you then those figures will not even concern you as you take your first beautifully exposed and developed negative to your enlarger. Phil Davis was certainly a photo geek but he was also extremely practical and his wonderful system reflects that.

Steve

[Ken Lee]

"If you choose to go BTZS with the lot then you will need to set up your darkroom with the ability to test your film according to the requirements of the system. No other test data or method will work - for BTZS. It is an integrated system..."

Thank you Steve - the timing of your message is fortuitous !

I just dusted off my enlarger, and put in one of my shutter-mounted view camera lenses. I'm hoping to do my first film test. (I had Fred Newman do one for me, so I know what to follow). I have a step-wedge and my densitometer will be back from the shop in a few days.

My wife tells me never to sell my old equipment, and I have to admit that I was thinking of ditching my enlarger - but now I'm really glad I kept it.

Even though I'm fairly familiar with the Zone System and manage to get some decent exposures now and then, it has been a valuable experience to study BTZS. More than simply giving a deeper understanding of how things work, it's having an impact on how I see.

For years I have seen things in terms of tones - perhaps a result of measuring reflected light. Using an incident meter places greater emphasis on the interplay between direct and indirect lighting - and makes one more aware of the quality of the light itself.

[Stephen Benskin]

Steve, this is something that I've been wondering about for sometime. What was Davis' reasoning for choosing to do a "work around" by increasing the aim negative density range when incorporating flare into curve analysis (page 95 3rd ed)? From my experience people tend to forget the reasons for a work around leading to misconceptions on how the underlying principle works. Also, what percentage of BTZS users do you think actually incorporate this flare adjustment into their analysis?

[Ken Lee]

If a scene is back-lit, how can it be evaluated with an incident meter ?

For example: a person standing directly in front of a window, in a white room. Most of the light is coming into the room through the window behind the person, and there is a little "fill" effect from the room.

We don't want the window behind the person to be pure white, and we'd like to know where it will be, depending on exposure, so that we can control contrast. The scene may be too contrasty for ordinary methods, but how do we evaluate it ? How do we determine the Subject Brightness Range ?

In a sense, the entire scene is in shadow, so getting a shadow reading is easy. Placing the meter in front of the person's face and pointing it towards the camera, we can measure the shadow illumination - but how do we meter the window itself ? If we hold the meter up against the window and point it towards the camera, the meter dome is shielded by the back of the meter, and all we get is another shadow reading.

[Shen45]

Steve, this is something that I've been wondering about for sometime. What was Davis' reasoning for choosing to do a "work around" by increasing the aim negative density range when incorporating flare into curve analysis (page 95 3rd ed)? From my experience people tend to forget the reasons for a work around leading to misconceptions on how the underlying principle works. Also, what percentage of BTZS users do you think actually incorporate this flare adjustment into their analysis?

Hi Stephen,

Thanks again for your knowledgeable contribution to this forum. I cannot speak to why Phil did what he did with BTZS but can attest to the most predictable and printable negative I have even had. I used the ZS for many years and while it works well the consistency of the negatives with BTZS is the real winner for me. As to flare the plotter doesn't "add" flare to the file created for export to the ExpoDev, that is something you add as a personal preference. For example for my Verito I use a different value compared to my RD Artar. Essentially the flare factor is more an experience thing. I also apply a different factor for one of my older cameras relative to a much newer camera with newer bellows. I would say most BTZS user based on the Expodev program apply a flare factor between .015 and .03.

Steve

[Shen45]

If a scene is back-lit, how can it be evaluated with an incident meter ?

For example: a person standing directly in front of a window, in a white room. Most of the light is coming into the room through the window behind the person, and there is a little "fill" effect from the room.

We don't want the window behind the person to be pure white, and we'd like to know where it will be, depending on exposure, so that we can control contrast. The scene may be too contrasty for ordinary methods, but how do we evaluate it ? How do we determine the Subject Brightness Range ?

In a sense, the entire scene is in shadow, so getting a shadow reading is easy. Placing the meter in front of the person's face and pointing it towards the camera, we can measure the shadow illumination - but how do we meter the window itself ? If we hold the meter up against the window and point it towards the camera, the meter dome is shielded by the back of the meter, and all we get is another shadow reading.

Hi Ken,

Highlight = Dome facing away from camera pointing at the brightest part of the window. Examine the window to see what is the brightest part of the scene and get as close as you can so the meter is evaluating just the highlight. That is your highlight reading.

Shadow = Dome at subject position pointed to the camera.

ExpoDev does the rest. If you want the window to "blow out" a little just point the meter toward the next less bright area of the window highlight area and use that lower highlight EV. Another way is to meter the brightest area you can find and add or subtract .5 to 1 EV. Incident metering does offer excellent creative possibilities.

Hope that helps.

Steve

[Stephen Benskin]

I cannot speak to why Phil did what he did with BTZS but can attest to the most predictable and printable negative I have even had. I used the ZS for many years and while it works well the consistency of the negatives with BTZS is the real winner for me. As to flare the plotter doesn't "add" flare to the file created for export to the ExpoDev, that is something you add as a personal preference. For example for my Verito I use a different value compared to my RD Artar. Essentially the flare factor is more an experience thing. I also apply a different factor for one of my older cameras relative to a much newer camera with newer bellows.

There's no doubt about the negatives. BTZS uses good solid tone reproduction theory. My major concern with BTZS is that Davis tends to gloss over some concepts. Maybe it's the simplification inherent to "systems" or maybe it's just to keep the book to a reasonable length. Otherwise, I agree with most of what he says.

I would say most BTZS user based on the Expodev program apply a flare factor between .015 and .03.

Isn't this the adjustment with the program? I'm more interested in how Davis describes factoring in a flare adjustment on paper and whether this concept is one that people tend to follow. While we're on the topic of the program, exactly how does it calculate the flare factor? Can you explain the math here?

[Mark Barendt]

The difference between the reading pointed at the light source, the window in your example, and the reading pointed at the camera tells us if the scene is a short, normal, or long scale. You use that info to decide on EI and processing.

Then those readings are used to decide on placement.

My impression is that BTZS pegs placement from the "at the camera" reading, Dunn averages the two readings to place exposure.

If a scene is back-lit, how can it be evaluated with an incident meter ?

[Bill Burk]

For years I have seen things in terms of tones - perhaps a result of measuring reflected light. Using an incident meter places greater emphasis on the interplay between direct and indirect lighting - and makes one more aware of the quality of the light itself.

Ken,

This post brought tears to my eyes, these few words have changed my attitude towards incident metering.