TMX "N" dev question

In completing the normal development test for my TMX (4x5) I have come across an issue that maybe someone can provide some insight. I exposed a few zone V and zone VIII sheets for various development times; I developed the first pair of zone V/VIII sheets along with an unexposed sheet for fb+f, and I used a development time of 10% less than Kodak's recommended time (only because when I completed the TMY tests "N" worked out nicely at 10% less than manuf. rec time, so I gave it a try for TMZ). Turns out that was not enough time for either zone V/VIII densities.

So, I went ahead and developed the next zone V/VIII pair at an additional 10% more time (and one for fb+f) and zone V worked out at a perfect 0.7 net density but zone VIII was net 1.18 which is .12 less than preferred. To me, this suggests an exposure error at Zone VIII, but after double checking EV's and my choice of f/stop and shutter for each exposure, it appears that the zone VIII shots were properly placed and exposed. Increasing development to raise zone VIII to a net of 1.3, I think, will push zone V beyond it's preferred range.

All thoughts and suggestions are welcome. Thanks.

Chuck

At what exposure index? TMZ is funny stuff. Very low in contrast when exposed and developed for its native ISO speed of around 800, it's designed to make a printable negative at much higher exposure indices when pushed. Put another way, the film is designed to be pushed. To me, at least, this is a most unsuitable film for zone system controls.

Oops!, I'm sorry, I meant to say TMX---the post is regarding TMX. Maybe a moderator can change that for me,

Thanks
Chuck

Chuck1 said:

...........zone V worked out at a perfect 0.7 net density but zone VIII was net 1.18 which is .12 less than preferred.............Increasing development to raise zone VIII to a net of 1.3, I think, will push zone V beyond it's preferred range.

All thoughts and suggestions are welcome. Thanks.

Chuck

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You had me excited there for a moment! A fast film in LF could be handy at times!

Back to your problem:
Wouldn't you expose a little less and then the extra development would get you more at zone_viii?

john_s said:

You had me excited there for a moment! A fast film in LF could be handy at times!

Back to your problem:
Wouldn't you expose a little less and then the extra development would get you more at zone_viii?

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I'm sure for those that do film testing there are some that put their own spin on how they test, but the idea, as I see it, with the ZS "normal" development test is not to tinker with the exposure to achieve the desired density result but to expose the sheet at zone VIII (three stops over the metered value) and provide just enough development for a target net density of 1.3 +- .05.

I believe I'm going to rest on that development time because zone V was right on at .7, the exact middle of the zone V range, but always open to suggestions. Perhaps the EV dropped a bit prior to exposure and I did not get a true zone VIII sheet, although my notes don't mention problems with changing EV's, IDK.

You don't mention your zone I density which should enter the exposure consideration. I would suggest reducing the EI and developing slightly less than you have. This would raise all the exposures but the reduction in development can bring V & VIII back down to your desired densities.

Chuck1 said:

I'm sure for those that do film testing there are some that put their own spin on how they test, but the idea, as I see it, with the ZS "normal" development test is not to tinker with the exposure to achieve the desired density result but to expose the sheet at zone VIII (three stops over the metered value) and provide just enough development for a target net density of 1.3 +- .05.

I believe I'm going to rest on that development time because zone V was right on at .7, the exact middle of the zone V range, but always open to suggestions. Perhaps the EV dropped a bit prior to exposure and I did not get a true zone VIII sheet, although my notes don't mention problems with changing EV's, IDK.

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But, you need to "expose for the shadows and develop for the highlights" which you are not doing. You appear to be exposing for the highlights (VIII) and developing for the midtones (V). That's backwards. You are trying to balance exposure and development around the middle when you really need to pin down the low end and let the development rise or fall in relation to that value.

Exposure affects the lower zones most while development affects the higher zones. So "overexposure" (lowering the EI) will cause all zones to increase in density but it will have the most profound effect on the shadows and won't mean diddly squat to zone VIII if the film is developed correctly ("underdeveloment" aka "compaction").

What EI are you using? My guess is that TMX probably comes in around 50 or 64 for most people doing film tests.

smieglitz said:

You don't mention your zone I density which should enter the exposure consideration. I would suggest reducing the EI and developing slightly less than you have. This would raise all the exposures but the reduction in development can bring V & VIII back down to your desired densities.

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For the film speed test, my TMX EI worked out to be 160 and the gross density was 0.14 with a fb+f density of .04 for a net of 0.1. I really did not want to mess with that as it is perfect.

smieglitz said:

But, you need to "expose for the shadows and develop for the highlights" which you are not doing. You appear to be exposing for the highlights (VIII) and developing for the midtones (V). That's backwards. You are trying to balance exposure and development around the middle when you really need to pin down the low end and let the development rise or fall in relation to that value.

Exposure affects the lower zones most while development affects the higher zones. So "overexposure" (lowering the EI) will cause all zones to increase in density but it will have the most profound effect on the shadows and won't mean diddly squat to zone VIII if the film is developed correctly ("underdeveloment" aka "compaction").

What EI are you using? My guess is that TMX probably comes in around 50 or 64 for most people doing film tests.

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With due respect, I have to disagree that I am developing for the mid-tones.

I am carrying out the test exactly as given in "The Negative" and elsewhere. Adams says to expose several zone V and zone VIII sheets, and.... "The Value V densities are given as a check on the middle range densities both at the Zone V and Zone VIII exposures". You would not want to manipulate the development time for VIII without knowing what affect you are having in the middle zones; with normal development, there should be no material change in Zone I because develpment there is complete well before the density for Zone VIII is established.

After carrying out the test it makes perfect sense, unless I have grossly misunderstood, that the zone V sheet is there for a check on the mid zone densities relative to the development provided for the zone VIII target. Since the VIII target is low but the V reference marker is perfect, this tells me that the issue may not be the development time at all but rather, something else (that's my reasoning anyway). Because, in the end, with "normal" development any way, Zone I = .09 -.11; Zone V = .65 - .75; and Zone VIII = 1.25 - 1.35. Of course, when N+1 or N+2 is planned, then those reference markers probably no longer apply because the fog levels will increase or decrease relative to the dev time and thus also, the effective film speed .

Zone I has been ascertained as noted in my previous response and thus exposure for the toe of the curve is assured when "normal" development is planned; so, development for the highlights is pretty much ascertained as well, I think, because I am now convinced that I had a drop in EV when I made that VIII exposure.

Thanks for responding.
Chuck

Chuck1 said:

With due respect, I have to disagree that I am developing for the mid-tones.

I am carrying out the test exactly as given in "The Negative" and elsewhere. Adams says to expose several zone V and zone VIII sheets, and.... "The Value V densities are given as a check on the middle range densities both at the Zone V and Zone VIII exposures". You would not want to manipulate the development time for VIII without knowing what affect you are having in the middle zones; with normal development, there should be no material change in Zone I because develpment there is complete well before the density for Zone VIII is established.

After carrying out the test it makes perfect sense, unless I have grossly misunderstood, that the zone V sheet is there for a check on the mid zone densities relative to the development provided for the zone VIII target. Since the VIII target is low but the V reference marker is perfect, this tells me that the issue may not be the development time at all but rather, something else (that's my reasoning anyway). Because, in the end, with "normal" development any way, Zone I = .09 -.11; Zone V = .65 - .75; and Zone VIII = 1.25 - 1.35. Of course, when N+1 or N+2 is planned, then those reference markers probably no longer apply because the fog levels will increase or decrease relative to the dev time and thus also, the effective film speed .

Zone I has been ascertained as noted in my previous response and thus exposure for the toe of the curve is assured when "normal" development is planned; so, development for the highlights is pretty much ascertained as well, I think, because I am now convinced that I had a drop in EV when I made that VIII exposure.

Thanks for responding.
Chuck

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Yes, Now that the zone I numbers are known the situation can be reevaluated. Two questions now: 1) Have you tested the exposure scale of the paper/process you will be using when printing these negatives to actually be sure for example zone V requires a density of.70 for that material and VIII is up at 1.30? Are these numbers coming via the paper or the book? 2) What developer and dilution are you using and how does it affect the curve shapes relative to another developer?

I find it unusual that your speed point for this film is coming in at EI150. My experience with it is in the other direction.

smieglitz said:

Yes, Now that the zone I numbers are known the situation can be reevaluated. Two questions now: 1) Have you tested the exposure scale of the paper/process you will be using when printing these negatives to actually be sure for example zone V requires a density of.70 for that material and VIII is up at 1.30? Are these numbers coming via the paper or the book? 2) What developer and dilution are you using and how does it affect the curve shapes relative to another developer?

I find it unusual that your speed point for this film is coming in at EI150. My experience with it is in the other direction.

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Absolutely, I find it unusual as well and I posted those results but did not get much feedback from anyone. I know my process is consistent so I guess I have to assume that that EI of 160 is correct----my EI for TMY worked out to be 640, again, unusual as both of those EI's are -2/3 off the box speed. But that's the reason for testing, everybodies equipment, style, and processing is different. Maybe I have a poorly calibrated shutter on my lens and this is how it shows up, IDK.

When I empirically tested before acquiring a densitometer I got really good results with my paper/developer (Ilford MG IV RC with dektol). And I was not too far off from those numbers empirically when I put those negatives (120) in the densitometer and measured them, I was amazed. Testing can certainly be done without a densitometer, but using one is so much quicker and easier, and with a better feeling of accuracy. To answer your question, no, I have not tested my paper, I'm just using those targets for now.

Thanks
Chuck

You are familiar with the sets of standard characteristic curves for films which the manufacturers put out. Basically, you adjust contrast by altering development time, and the position of the curve horizontally by altering exposure. Now, you have decided that you want to set three points of the curve to predetermined values. (Zones i, v and viii). It seems that the curve shape is not going to give exactly this to you with your current developer and development technique. Fitting two points is always possible, of course. Which is why the general texts on zone system suggest that two points be considered: traditionally zones 1 and about 8 iirc. Lots of people think that accuracy at zone 1 is not as important as getting a value around zone 3 right, and i agree with that.

There are ways to slightly alter the shape a bit (developer choice, dilution, agitation). And different films have different shapes (e.g. longer toes, roll off at high zones)

Chuck1 said:

...........Maybe I have a poorly calibrated shutter on my lens and this is how it shows up, IDK..........

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We introduce problems for ourselves with accurate desitometers. What was once unnoticed is now an inconsistency, a problem to be solved. Most mechanical shutters will be a bit inaccurate. If you do a series of zones 1 to 8 by altering shutter speed, then do it again with a different aperture so that zones are at different shutter speeds, you are very likely to see that some speeds cause irregularities in the curve. Usually we ignore this, so don't worry about it unless it's a big inconsistency. Buying a shutter speed measuring device is overkill. As you said, pre-densitometer you didn't have a problem.

john_s said:

As you said, pre-densitometer you didn't have a problem.

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John,

Nothing I'm doing is meant to construct a characteristic curve at this point----I'm just doing the speed test and "N" dev test, that's all.

Pre-densitometer I did pretty well but it was not without inconsistencies. I can see already that post-densitometer it will be even better. It's just a tool and I guess it's all in how smartly it is used.

Thanks
Chuck

Chuck1 said:

....Nothing I'm doing is meant to construct a characteristic curve at this point----I'm just doing the speed test and "N" dev test, that's all..........

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Hi Chuck, I know that you're not out to create a characteristic curve, but I was trying to interpret your situation by using the concept of the curve that would describe your film+dev combination. You might not be able to get three points to fit your predetermined data points exactly.

BTZS Film Test

I suggest using the BTZS film testing service at the View Camera Store, one of the advertisers here. I just did the same and am very happy after previously doing the same tests you are doing. It will answer your questions objectively and save you a lot of time.

They charge $45 and send you 5 sheets of the film of your choice, already exposed to a step tablet. You process each sheet of the film at a different time, e.g 4 min, 5.5 min, 8 min, 11 min, and 16 minutes and then send the developed film back. They will do the densitometer readings, run it through their plotter software, and send you all of the graphs and tables. for the Zone System, you will use a table that shows the film speed for N-1, N, N+1 etc and also the development times for each. Using their software you can determine proper EI and development time for each exposure. I think it is a bargain

Chuck1 said:

John,
Nothing I'm doing is meant to construct a characteristic curve at this point----I'm just doing the speed test and "N" dev test, that's all.
Thanks
Chuck

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OK, Chuck, please let me chime in. I have read the thread up til now and I can help out, if you are open. I have used the ZS for many years and I used to teach it at workshops. It's really a simple process but it can be frustrating due to the issues that have already been raised.

So let's clarify.

1) you have done your film speed test and you got asa 160. Good.
2) you have a target density for your Zone VIII of 1.3 which, as I understand it, you got by evaluating the density range of your paper. This is a realistic value for FB silver gelatin papers.
3) You seem a little hung up on the Zone V density. Forget it, it is not important and I don't care what the books say. You do your development time tests for N development using Zone VIII densities ONLY. You need to increase development until you hit your target density. Forget where Zone V lands. As it stands, your current densities are not that far off. A difference of .10 is only 1/3rd of a stop, more than accurate enough. If you want you can try to get the exact density, but you won't be able to do that repeatedly so who bother? Once you get within .10 on the densitometer to your target Zone VIII densitiy, stop and pat yourself on the back. You now know your N development time.
4) After you know your N time, shoot Zones I thru Zone IX and develop for your normal time. Read the Zone I and Zone VIII densities and see how they compare to the targets. Don't freak out if Zone VIII is .10 of .15 off. It's all an aproximation. Then, plot your first curve.
5) Continue on as your texts say for N+1 and N-1. You can probably hold off on N+2 and N-2 unless you shoot in very low or very high contrast situations.

Let me know if this doesn't answer your questions and congratulations for being willing to do the tests, I know how frustration they can be.

-R

reggie said:

OK, Chuck, please let me chime in. I have read the thread up til now and I can help out, if you are open. I have used the ZS for many years and I used to teach it at workshops. It's really a simple process but it can be frustrating due to the issues that have already been raised.

So let's clarify.

1) you have done your film speed test and you got asa 160. Good.
2) you have a target density for your Zone VIII of 1.3 which, as I understand it, you got by evaluating the density range of your paper. This is a realistic value for FB silver gelatin papers.
3) You seem a little hung up on the Zone V density. Forget it, it is not important and I don't care what the books say. You do your development time tests for N development using Zone VIII densities ONLY. You need to increase development until you hit your target density. Forget where Zone V lands. As it stands, your current densities are not that far off. A difference of .10 is only 1/3rd of a stop, more than accurate enough. If you want you can try to get the exact density, but you won't be able to do that repeatedly so who bother? Once you get within .10 on the densitometer to your target Zone VIII densitiy, stop and pat yourself on the back. You now know your N development time.
4) After you know your N time, shoot Zones I thru Zone IX and develop for your normal time. Read the Zone I and Zone VIII densities and see how they compare to the targets. Don't freak out if Zone VIII is .10 of .15 off. It's all an aproximation. Then, plot your first curve.
5) Continue on as your texts say for N+1 and N-1. You can probably hold off on N+2 and N-2 unless you shoot in very low or very high contrast situations.

Let me know if this doesn't answer your questions and congratulations for being willing to do the tests, I know how frustration they can be.

-R

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Reggie,

Thanks for the response. There is really no frustration at all on my part regarding the testing as I am quite comfortable in performing it and interpreting it.

I have, since the OP, exposed two more sheets and developed them with the same time that I had when the first zone VIII read way too low. This time Zone VIII with a net of 1.28 (within the acceptable range) and zone V at .72 (also within the acceptable range). As I pointed out in an earlier post, I probably had a drop in EV when I exposed the first zone VIII sheet, resulting in a too low a density.

Thanks
Chuck

Chuck1 said:

Reggie,

Thanks for the response. There is really no frustration at all on my part regarding the testing as I am quite comfortable in performing it and interpreting it.

I have, since the OP, exposed two more sheets and developed them with the same time that I had when the first zone VIII read way too low. This time Zone VIII with a net of 1.28 (within the acceptable range) and zone V at .72 (also within the acceptable range). As I pointed out in an earlier post, I probably had a drop in EV when I exposed the first zone VIII sheet, resulting in a too low a density.

Thanks
Chuck

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Hi Chuck. It's important to understand that Zone V does not have an 'acceptible' range, but Zone VIII does. Zone V will fall where it does based on the inherent characteristics of the film (thus, 'characteristic curve') and there is nothing you can do about it. You're wasting film even shooting it during your tests.

But it's great news that you got your N time now! I'd shoot Zone I-Zone IX,
plot the curve and then do N-1 and N+1 and then go have fun shooting.

Your prints will turn out very rich and full toned.

Good luck.

-R

reggie said:

Hi Chuck. It's important to understand that Zone V does not have an 'acceptible' range, but Zone VIII does. Zone V will fall where it does based on the inherent characteristics of the film (thus, 'characteristic curve') and there is nothing you can do about it. You're wasting film even shooting it during your tests.

But it's great news that you got your N time now! I'd shoot Zone I-Zone IX,
plot the curve and then do N-1 and N+1 and then go have fun shooting.

Your prints will turn out very rich and full toned.

Good luck.

-R

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Reggie,

Thanks. I guess in my own defense is that I am totally self taught in all this as I've never had a class or even worked with a photographer who knows the ZS----just me and my books to learn from and to try and apply what I've learned. We'll just have to disagree on the zone V issue. Adams says that it is "a reference value for the "local contrast" effect". Through my own understanding that makes sense to me and I don't feel it is a waste of film. I don't find it ironic that when "normal" development for zone viii gives a net density of 1.25 to 1.35, then the net density for zone v is .65 to .75-----this has been the case for both TMY and TMX. But you are right, I look forward to using these two films and having fun with them.

Chuck

Chuck1 said:

Reggie,

Thanks. I guess in my own defense is that I am totally self taught in all this as I've never had a class or even worked with a photographer who knows the ZS----just me and my books to learn from and to try and apply what I've learned. Chuck

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This brings back memories. I started out EXACTLY the same way, just me and the Fred Picker book. I didn't even know what a densitomoter was, and I always relied on the meter to give me the 'correct' exposre. Then I read more and just thought about it and I picked it up pretty quickly and then I started teaching once I was able to put the ZS to practice in the field. It's just basic sensitometry and it works great for me. I almost never shoot outside the +2/-2 range.Thirty years later, here I am still using it and helping other people including my clutzy friends<g>.

If you want to hang onto keeping an eye out on Zone V, here is something you can try. If you test other films, keep an eye out for one that gives a .1 for Zone I, a 1.3 for Zone VIII and then a value greater than the reference value for Zone V (a significant difference like .2 or .3 above the reference while at the same time giving a 1.3 for Zone VIII). Then immediately rush to APUG and PM me the name of that film! Chart out what that will look like and then intrepret what that will mean visually and you'll see why I'm interested.

Another thing to try is 'shifting Zone I' to the right. If you plot a film that has a long toe where the curve hugs the axis for 1 or two stops such that when it finally starts to curve upwards it is at a density of about .2 or .25, then you can make that point your Zone I density. Zone I does not have to be .1, .2 or .25 is ok. For a film like this this will mean that you'll get more shadow seperation when you shoot it at the asa that produced a Zone I of .2 or so. Moving the toe is a common technique and when you 'grok' this then you'll start to show a mastery of the ZS. You can keep the same development time or vrey slightly increase it.

There are chemical things that you can do to alter the overall characteristic curve of the film and to raise shadow detail (increase light sensitivity in the toe). One is 'flasing' the film before loading it. Old timers sometimes loaded sheetfilm in the dim moonlight rather than total dark. The small amount of light that hit the film 'pre exposed' the film just a little, but not enough to fog it overall. This little extra exposure makes the film more sensitive to light and shadows will record better with no change to Zone VIII values

Another technique, one that I've only read about, is to pre-bleach the film. A man named Michael Johnson once wrote about this but it seemed like a troublesome approach that didn't really catch on. Maybe someone here can post about if they're tried it. It alters the characteristic curve of the film, too, and is supposed to be one of those really cool and helpful things to do.

Sorry for the long posts and I hope you enjoy the newfound control you now have over the B&W process, Chuck.

Take care and write when you learn how.

-R

reggie said:

...
Another technique, one that I've only read about, is to pre-bleach the film. A man named Michael Johnson once wrote about this...
-R

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Sounds like SLIMT (Selective Latent Image something or other) used by David Kachel (sp?) who wrote a series of articles about it in Photo Techniques magazine many years ago. I think he actually holds workshops on the technique which supposedly allows for large degrees of compaction in the range of N-4.

smieglitz said:

Sounds like SLIMT (Selective Latent Image something or other) used by David Kachel (sp?) who wrote a series of articles about it in Photo Techniques magazine many years ago. I think he actually holds workshops on the technique which supposedly allows for large degrees of compaction in the range of N-4.

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You nailed it right on the head, 'Selective Latent Image Somethig Or Other' ;>). I don't recall David Kachel, but I do recall Michael Johnson writing about it. But that is pretty far down the road for Chuck.

-R