BTZS expodev question

[swmcl]

Hi,

Can someone tell me what the hi-zone variable in the Expodev / Metering / Zone section is please ?

Under the Zone system tab, there are 4 variables. Lo-EV, Hi-EV, Lo-Zone and Hi-Zone.

I sample my scene, I put in the lo and hi EV readings, I understand the Lo-Zone should be where I wish to place the Lo-Ev reading but what of the Hi-Zone ?

I need to understand what the Hi-Zone variable is doing ...

The other issue is that it won't go beyond 10.0

Cheers,

Steve

[limnidytis]

If you are metering by the zone system, the lo/hi EV values are what you read with your spot meter. The zone values are the zones where you want to place the readings. I assume you know the program requires raw data from a film test to use as a basis for calculations.

[swmcl]

Thanks for the reply.

Yes I have a fully tested film and developer combination in place. The zone values are what zones ? On the paper ? Why would I put in zones when I've already put in the EV values between which I have decided is the information I wish to record ?? It is fairly obvious to me (and to no-one else !) that my high EV value is the 'very nearly white' point on the paper and the low EV reading is the 'very nearly black' point on the paper ... I just don't get the zonal information being asked for ... and it isn't trivial because the resulting calculations affects the SBR and recommended exposure that the software comes up with ...

The limit of 10 Zones ? We all know the film records more than 10 zones so this must be a paper zones spread ... ??

The user manual is almost none existent. As the original author has passed perhaps those who are continuing the software actually don't know the product as well as they might ?? The user manual is almost a cynical joke in my view.

Frustrated.

[ic-racer]

For example, the HIGH value does not have to be your "very nearly white" value. One can choose to use the next values lower because maybe the "very nearly white" value is difficult to meter or not existing in the scene. So if you use zone VI for that high value you enter zone six with its corresponding EV value.

Unless you are including light sources in your scene, many scenes, when projected on the film plane, will max out below 10 zones.

BTZS is not perfect. I don't use it, but it has many supporters and it works as well as any other exposure/development system when you get it figured out.

[swmcl]

Thanks ic,

I do trust your judgement. Ya just gotta understand I feel a bit left out in the cold ... especially with the user manual.

For everyday normal printing to the fullest scale possible would it not be always the case where you'd leave the hi-zone and lo-zone alone altogether ? Say set them to 1 and 9 and forget it ?

Thanks for your reply too BTW.

[chris_4622]

The SBR won't always fit the scenario you mention, leaving the hi/low zone set to 1 and 9, so you have to decide where you want to place the corresponding EV. For example a scene where the EV range is 7 to 12 you can put the 5 stops in your choice of zones; 2 to 7, 3 to 8 etc. you can also expand or contract the zone range within the limits of the film. The zone range in the app is for printing reference.
Hope this helps.

[swmcl]

Thanks Chris,

So if I measure a scene and its range is say 7 stops or EV then I put the same range in the zone settings say centred around 5 so for a 7 stop range it would be 1.5 and 8.5 ... ?

I'm thinking it would be a range floating in the centre rather than anchored to one end or another ...

This is getting better for the asking, thanks all.

This means of course that the 10 zone range I was referring to earlier is an SBR limit then ... hmmm

The developer test that I have done is such that the dev doesn't like the pulling of film. It isn't a go-slow developer so the CI figures are quite steep from a small dev time. If I wanted to get more of a range of the scene into the print I'd need a flatter curve and less aggressive developer. That or I'd need to start again with stand development or a two bath developer.

I wonder if the Expodev is going to fall over with the idea of stand development ...

I'm learning heaps but I'm also burning film on dumb testing ... :-)

I feel that I will be far more able to produce a really effective negative though. My confidence is rising slowly ... LF and sheet film is a significant science as well as an art. I'm not one for hoping all will be well when I shoot. I wonder if you can tell that :-(

Cheers,

Steve

[limnidytis]

It helped me to read the BTZS book 4-5 times, and make notes. Reading some of the old DMax newsletters helped, too as there are several that focus on film testing. You can buy copies of the news letters from the View Camera Store.
It may not be explicitly stated, but the system is designed to give a N time of about 8 minutes, so you have curves above and below the 8 min curve to allow for +/- calculations. When initially testing, you can just test the 8 min time. The curve should have a gradient of about 0.5, which is considered N in BTZS. If the curve is far off from 0.5, you should change you developer dilution to adjust the curve to 0.5 at 8 min, then complete the film test with the other times. I would doubt you could get the system to work with stand development. I find expodev to be handy - it automates all of the binary math calculations.

[swmcl]

Hi limnidytis,

I've got the book and as far as I can see there is no reference to the Lo Zone nor Hi zone - the Phil Davis book that is ...

The default is 3 and 7 as I recall. I can see that changing them does change at least the development time for the film so I need to know what they do. I believe they are paper limits but I don't know much more than that. For example, can they be expanded to say 1 and 9 ? If they are there as a print tonality control which will require a more intimate knowledge of the paper characteristic then that's fine but what do others do? DO they just stay within a 4 value range and move that around - say go from 2 to 6 instead of 3 to 7 ?

I'll try to find some more papers like the DMax stuff you mention too.

Rgds,

[Bill Burk]

Hi swmcl,

In classic Zone System metering, you can take any two meter readings and place them on any two Zones of your choice (but you cannot make them crossover).

So a typical normal scenario you can read a shadow, place it on Zone II... then read the palm of your hand and place it on Zone VI. That's enough information to determine exposure and development...

Here is an example of that. This places Low EV on Zone II and Hi EV on Zone VI:

Low EV = 5
Low Zone = 2

Hi EV = 9
Hi Zone = 6

If you plug those numbers in, I think you will get a normal "N" development time.

This may help confirm that's the right way to do Zone System placement: This should give exactly the same recommended exposure and development time as the first example:

Hi EV = 8
Hi Zone = 5

Hi EV = 10
Hi Zone = 7

And if you want to make your hand look brighter in the print, you can input this and you should expect "N+1" as a result.

Hi EV = 9
Hi Zone = 7

[swmcl]

Righto !

There is a 4 'stop' difference in your first example between the hi-zone and lo-zone. I've a feeling this is normal. I think I should keep the 4 stop difference no matter what.

My outside scene from under a nearby tree to the white clouds had Lo-Ev 10.2 and Hi-Ev 17.1 measured with an L358 Sekonic on spot @ 100 ISO. If I pair that with Lo-Zone 3 and Hi-Zone 7 I think I'll be in the ballpark.

I don't follow the second half of the post though, sorry. It's not mentioning any Lo-Ev or Lo-Zones.

Cheers,

Steve

[Bill Burk]

I meant for you to keep the Lo-EV and Lo-Zone the same in the second half.

My first example came up with 4 stops difference between two metered points, but I didn't discuss the darkest and lightest points. I considered a darkest point and a point just a stop lighter than middle gray.

In Zone System parlance, I picked two parts of my scene and placed them where I wanted them to print. The recommendation from the application would be an exposure and development time that would aim to give me a negative that prints on my normal paper.

My imaginary scene may well have had 7 stops of subject brightness range, for example there might be clouds in my picture too but I didn't talk about them.

I allowed the clouds to "fall" where they may (using Zone System terminology).

You metered a scene with 7 stops difference between your low reading and your high reading. You might have considered the clouds important enough to demand detail.

If you place your shadow on Zone II and place your highlight on Zone VIII the settings may look like this:

Lo-EV 10.2
Lo-Zone 2

Hi-EV 17.1
Hi-Zone 8

I think the application might give you a result suggesting "N-1" development time, which would help keep the clouds from blocking up.

[swmcl]

Yes.

LoEv 10.3, HiEv 17.1, LoZ 2, HiZ 8 results in SBR 7.9, G 0.46, EFS 25 and 1/8th @ f16 2/3 for 6min50secs (delta zone = 6)

then

LoEv 10.3, HiEv 17.1, LoZ 2.8, HiZ 7.2 results in SBR 10.8, G 0.34, EFS 25 and 1/4 @ f16 1/2 for 5m06secs (delta zone = 4.4)

So the dev time gets shortened and therefore the film is a lower G for a smaller range of Zone.

The paper zonal range is shorter than the film zonal range for sure but I just don't know what a happy medium is at this stage.

Thanks for your help so far.

The placement of shadows etc. on particular zones is not something I can do in the software. It just tells me what to do in terms of exposure and development. I wouldn't know how to dictate to it on how to place a reading as such.

Cheers,

Steve

[Bill Burk]

The placement of shadows etc. on particular zones is not something I can do in the software. It just tells me what to do in terms of exposure and development. I wouldn't know how to dictate to it on how to place a reading as such.

You are doing Zone Placement when you use those two boxes Lo-Zone and Hi-Zone.

That's what the software is doing, that's what Zone System does.

The program and Zone System on paper both tell you exposure and development given two meter points and what print zone you want those two points to be printed as.

That's why, for example, when you enter a higher Hi-Zone you are told to develop longer... to make a higher density highlight which will print whiter.

You enter the paper on another screen.

[swmcl]

So is the Hi-Zone of 10 in the software the maximum zone on the paper - relative to the paper ?

So for example, if I have a paper that can show 5 zones, does the software effectively put the highest zone of 5 at the '10' ? Or if the paper is a 5 zone paper you should not then spread the zones by more than 5 between the lo-zone and hi-zone settings in the software ??

In my question above, the settings in the software would be breaking up the 5 zones on the paper between 10 settings (half a zone per whole number) (a) or you would have a 1:1 correlation (b).

Sorry for the persistent questions !

[swmcl]

Even better ...

If I can manage to upload a screenshot of a common grade 2 paper could you please tell me where the various 'zone' numbers on the software would probably fall on the paper ?? That would help enormously.

Let's see how I go at uploading the screenshot...

[Bill Burk]

The two entries Lo-Zone and Hi-Zone are Paper Zones. For simplicity, think of Lo-Zone = 0 as black as paper can go. And Hi-Zone = 10 as white as paper can go. (For calibration they are nearly black and nearly white, according to certain directions you follow depending on the teacher).

For the Zone System, any paper you calibrate has 10 Zones. The Zone System is what relates the paper to the film and the film to the scene.

Your subject is where things go wild and might have 7 Zones or 14 Zones and you have to expand (by developing longer) or compress (by using a compensating developer or less developing time) the negative so that it fits the paper.. in a way that the paper should be expected to go from black to white under your negative.

In a real scene, you will meter something dark, suppose the bark of a tree in shade... and you will intend to print it pretty dark on paper. So you get Lo-EV = 10 and Lo-Zone = 2 to say "Place the shadow on Zone II". You don't often place low meter readings on Zone 0, or even on Zone I. That's because you want to see the bark texture in the print, if you look close at the print.

Then you meter something near the upper end of what will be in the picture, and you think about how bright you want it to appear on the print. It helps if you choose something that is bright but important enough that you want to see detail, and then place that on a high zone such as Zone VIII. That's where you get Hi-EV = 17.1 and Hi-Zone = 8

In another way of using Zone System metering of the same scene, suppose you put a person in it, and the skin tone is the most important highlight. You don't put the skin tone on paper white, you put it on light gray, which in Zone System terms is Zone VI.

This is how you might meter that same scene, and the results might be the same or might be a little different, but this is a better set of metering for the person...

Lo-EV = 10 and Lo-Zone = 2

Hi-EV = 15 and Hi-Zone = 6

[Bill Burk]

Suppose the dot above 2.50 is Zone IX

And the dot above 1.22 is Zone I

There's 8 divisions if you count off Zones going across so 2.5 - 1.22 = 1.28

1.28 / 8 = 0.16

So draw a line on the x-axis at:
2.34 = Zone VIII
2.18 = Zone VII
2.02 = Zone VI
etc.

Now that's your 10 Zones on paper.

Getting the negative to fit the paper means making a negative that relates to that x-axis in terms of density.

[swmcl]

Excellent !

Thank you heaps.

In the end, all I was asking was for a couple of values to put into the ExpoDev program so that I could shoot using my data and be fairly confident of being able to print at a later date. What I'll do having had this discussion is on a crazily wide scene SBR I'll use 2 and 8 or even 1.5 and 8.5. On a more modest scene where there is an SBR of say 5 or so rather than the 7 that I quoted before I could use 2 and 6 for this. or 2 and 7 even.

This is a wonderful result and I feel much more educated.

Thanks again.

[Stephen Benskin]

Here are a few examples of Zone Placement on a paper curve.

Example 1. Equally spaced along log-H axis. Zone I and Zone VIII falling on the ISO 90% D-Max and 0.04 over Fb+f LER criteria.

129506

Example 2. Jack Holm's preferred Zones. From his paper Exposure Relations and Tone Reproduction, which can be found on APUG.

129507

Example 3. Comparing equally spaced Zones with the Munsell scale. The Munsell scale is based on perceived equally spaced tonal differences.

129508

[Kevin J. Kolosky]

if you take a white piece of cloth with texture, and a very dark piece of cloth with texture, and you put them into a "normal" sunlit scene, with the white card in the sun and the dark card in the shade. you will find 7 zones difference. if you put the dark cloth on zone 2, you then have zones 2, 3, 4, 5, 6, 7, and 8. If you then make a contact print at the shortest time to make the film edge black, you should see texture in both the dark and white cloths. If you don't in the dark cloth, you need to add more exposure (lower iso setting) if you don't in the white cloth you need to develop film a bit less (make neg less dense so more light can get through to print the texture)

Now match that up to your computer program.

[Bill Burk]

That's as simple a test as any.

[swmcl]

Mr Benskin thank you for your recommendation but how do I find the Holm paper ? I've searched and can't see it on APUG. Would it be listed under Holm ?

Thank you all and certainly Bill.

We've just had the remnants of a cyclone pass by but I hope tomorrow might be an opportunity to go out with my new setup and see what happens ... !

[Stephen Benskin]

Mr Benskin thank you for your recommendation but how do I find the Holm paper ? I've searched and can't see it on APUG. Would it be listed under Holm ?

Thank you all and certainly Bill.

We've just had the remnants of a cyclone pass by but I hope tomorrow might be an opportunity to go out with my new setup and see what happens ... !

I'm having trouble finding it over there too. Unfortunately the file is too large to upload here. Send me your email address in a private message and I'll email it.